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Sample records for acid herbicides mcpa

  1. An unusual case of non-fatal poisoning due to herbicide 4-chloro-2-methyl phenoxyacetic acid (MCPA).

    PubMed

    Tennakoon, D A S Sakunthala; Perera, K A P Bandumala; Hathurusinghe, L S

    2014-10-01

    MCPA (4-chloro-2-methyl phenoxyacetic acid) is a systemic hormone-type selective herbicide readily absorbed by leaves and roots. Use of MCPA for murder or attempted murder is very rare in Sri Lanka. However, a reported case of attempted murder by adding MCPA to water will be discussed in this paper. Three extraction methods were carried out with urine samples spiked with MCPA, namely liquid-liquid extraction with chloroform, solid phase extraction using C18 cartridges and vortex mixing with methanolic hydrochloric acid. Based on the recovery results, solid phase extraction was selected as the most suitable method and applied in the analysis of urine and water samples. Identification of MCPA in urine, water and the suspected poison bottle was carried out by HPLC and was confirmed by GC-MS. 4-chloro -2- methyl phenol metabolite was also identified and confirmed in the urine sample of the patient by GC-MS. Quantitative analysis of MCPA was carried out by HPLC using a validated method where Zorbax XDB-C18 column was used with photo diode array detector. In this case, presence of MCPA in one patient's urine sample collected four days after the incident was confirmed by GC-MS and found at a concentration of 0.83μg/ml. MCPA was not identified in the urine samples collected after 13 days in other three patients. The water sample taken from the suspected water storage tank found to contain 101μg/ml of MCPA. The results showed that HPLC combined with GC-MS is suitable for forensic analysis of MCPA in urine. PMID:24867053

  2. Urea Fertilizer and pH Influence on Sorption Process of Flumetsulam and MCPA Acidic Herbicides in a Volcanic Soil.

    PubMed

    Palma, Graciela; Jorquera, Milko; Demanet, Rolando; Elgueta, Sebastian; Briceño, Gabriela; de la Luz Mora, María

    2016-01-01

    The aim of this study was to evaluate the influence of urea fertilizer and pH on the sorption process of two acidic herbicides, flumetsulam (2',6'-difluoro-5-methyl[1,2,4]triazolo[1,5-a]pyrimidine-2-sulfonanilide) and MCPA (4-chloro--tolyloxyacetic acid), on an Andisol. Urea reduced the adsorption of MCPA but not that of flumetsulam. The Freundlich parameter of MCPA decreased from 8.5 to 5.1 mg L kg. This finding could be attributed to an increase in dissolved organic C due to an initial increase in soil pH for urea application. The higher acidic character of MCPA compared with that of flumetsulam produced a greater hydrolysis of urea, leading to a further pH increase. A marked effect of pH on the adsorption of both herbicides was observed. The organic C distribution coefficient () values for flumetsulam were in the range of 74 to 10 L kg, while those of MCPA were in the range of 208 to 45 L kg. In the kinetic studies, the pseudo-second-order model appeared to fit the data best ( > 0.994). The initial adsorption rates () ranged from 20.00 to 4.59 mg kg h for flumetsulam and from 125.00 to 25.60 mg kg hfor MCPA. Both herbicides were adsorbed rapidly during the first stage of the sorption process, and the rates of sorption were dependent on pH. The application of the Elovich and Weber-Morris models led us to conclude that mass transfer through the boundary layer and, to a lesser degree, intraparticle diffusion were influenced by the chemical character of the herbicide. These results suggest that urea application could increase leaching of acid herbicides in soils. PMID:26828188

  3. Toxicity of synthetic herbicides containing 2,4-D and MCPA moieties towards Pseudomonas putida mt-2 and its response at the level of membrane fatty acid composition.

    PubMed

    Piotrowska, Aleksandra; Syguda, Anna; Chrzanowski, Łukasz; Heipieper, Hermann J

    2016-02-01

    One of the attempts to create more effective herbicidal compounds includes the use of ionic liquids. Herbicidal ionic liquids have more effective biological activity, they are less volatile, more thermally stable, and exhibit superior efficiency in comparison to typically employed herbicides, allowing the reduction of the herbicide dose applied per hectare. However, studies on the environmental toxicity of this group of compounds are very rarely available. Environmental toxicity is an important factor, showing the concentration of compounds that has negative effects on soil bacteria including those responsible for biodegradation processes. Therefore, potential toxicity of four herbicidal ionic liquids (HILs) precursors containing 2,4-D and MCPA moieties was tested with the well investigated model organism for toxicity and adaptation, Pseudomonas putida mt-2. Results were compared to those obtained for commercial 2,4-D and MCPA herbicides. Next to growth inhibition, given as EC50, changes in the isomerisation of cis to trans unsaturated fatty acids were applied as proxy for cellular stress adaptation to toxic substances. The results revealed that all investigated precursors of HILs showed lower toxicity compared to commercialized synthetic herbicides 2,4-D and MCPA. The collected data on toxicity of HILs together with their physico-chemical properties might be useful for assessing the potential risk of the environmental pollution as well as guidelines for setting the legislation for their future use. PMID:26347932

  4. Comparative sorption and leaching study of the herbicides fluometuron and 4-chloro-2-methylphenoxyacetic acid (MCPA) in a soil amended with biochars and other sorbents.

    PubMed

    Cabrera, Alegria; Cox, Lucia; Spokas, Kurt A; Celis, Rafael; Hermosín, M Carmen; Cornejo, Juan; Koskinen, William C

    2011-12-14

    Biochar, the solid residual remaining after the thermochemical transformation of biomass for carbon sequestration, has been proposed to be used as a soil amendment, because of its agronomic benefits. The effect of amending soil with six biochars made from different feedstocks on the sorption and leaching of fluometuron and 4-chloro-2-methylphenoxyacetic acid (MCPA) was compared to the effect of other sorbents: an activated carbon, a Ca-rich Arizona montmorillonite modified with hexadecyltrimethylammonium organic cation (SA-HDTMA), and an agricultural organic residue from olive oil production (OOW). Soil was amended at 2% (w/w), and studies were performed following a batch equilibration procedure. Sorption of both herbicides increased in all amended soils, but decreased in soil amended with a biochar produced from macadamia nut shells made with fast pyrolysis. Lower leaching of the herbicides was observed in the soils amended with the biochars with higher surface areas BC5 and BC6 and the organoclay (OCl). Despite the increase in herbicide sorption in soils amended with two hardwood biochars (BC1 and BC3) and OOW, leaching of fluometuron and MCPA was enhanced with the addition of these amendments as compared to the unamended soil. The increased leaching is due to some amendments' soluble organic compounds, which compete or associate with herbicide molecules, enhancing their soil mobility. Thus, the results indicate that not all biochar amendments will increase sorption and decrease leaching of fluometuron and MCPA. Furthermore, the amount and composition of the organic carbon (OC) content of the amendment, especially the soluble part (DOC), can play an important role in the sorption and leaching of these herbicides. PMID:22023336

  5. 40 CFR 180.339 - MCPA; tolerances for residues.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...; tolerances for residues. (a) General. (1) Tolerances are established for residues of the herbicide MCPA ((4... for residues of the herbicide MCPA ((4-chloro-2-methylphenoxy)acetic acid) resulting from the...

  6. 40 CFR 180.339 - MCPA; tolerances for residues.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...; tolerances for residues. (a) General. (1) Tolerances are established for residues of the herbicide MCPA ((4... for residues of the herbicide MCPA ((4-chloro-2-methylphenoxy)acetic acid) resulting from the...

  7. 40 CFR 180.339 - MCPA; tolerances for residues.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...; tolerances for residues. (a) General. (1) Tolerances are established for residues of the herbicide MCPA ((4... for residues of the herbicide MCPA ((4-chloro-2-methylphenoxy)acetic acid) resulting from the...

  8. 40 CFR 180.339 - MCPA; tolerances for residues.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...; tolerances for residues. (a) General. (1) Tolerances are established for residues of the herbicide MCPA ((4... for residues of the herbicide MCPA ((4-chloro-2-methylphenoxy)acetic acid) resulting from the...

  9. 40 CFR 180.339 - MCPA; tolerances for residues.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...; tolerances for residues. (a) General. (1) Tolerances are established for residues of the herbicide MCPA ((4... for residues of the herbicide MCPA ((4-chloro-2-methylphenoxy)acetic acid) resulting from the...

  10. 2-Methyl-4-chlorophenoxyacetic acid (MCPA)

    Integrated Risk Information System (IRIS)

    2 - Methyl - 4 - chlorophenoxyacetic acid ( MCPA ) ; CASRN 94 - 74 - 6 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard

  11. Electrochemical sensor for simultaneous determination of herbicide MCPA and its metabolite 4-chloro-2-methylphenol. Application to photodegradation environmental monitoring.

    PubMed

    Rahemi, V; Garrido, J M P J; Borges, F; Brett, C M A; Garrido, E M P J

    2015-03-01

    The development and application of a polyaniline/carbon nanotube (CNT) cyclodextrin matrix (PANI-β-CD/MWCNT)-based electrochemical sensor for the quantitative determination of the herbicide 4-chloro-2-methylphenoxyacetic acid (MCPA) and its main transformation product 4-chloro-2-methylphenol in natural waters are described. A simple cyclic voltammetry-based electrochemical methodology, in phosphate buffer solution at pH 6.0, was used to develop a method to determine both MCPA and 4-chloro-2-methylphenol, without any previous extraction or derivatization steps. A linear concentration range (10 to 50 μmol L(-1)) and detection limits of 1.1 and 1.9 μmol L(-1), respectively, were achieved using optimized cyclic voltammetric parameters. The proposed method was successfully applied to the determination of MCPA and 4-chloro-2-methylphenol in natural water samples with satisfactory recoveries (94 to 107%) and in good agreement with the results obtained by an established high-performance liquid chromatography technique, no significant differences being found between the methods. Interferences from ionic species and other herbicides used for broad-leaf weed control were shown to be small. The newly developed methodology was also successfully applied to MCPA photodegradation environmental studies. PMID:25315934

  12. Influence of soil biochar aging on sorption of the herbicides MCPA, nicosulfuron, terbuthylazine, indaziflam, and fluoroethyldiaminotriazine

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sorption of four herbicides and a metabolite of indaziflam on a fresh macadamia nut biochar and biochars aged one or two years in soil was characterized. On fresh biochar, the sorption was terbuthylazine (Kd = 595) > indaziflam (Kd = 162) > MCPA (Kd = 7.5) > fluoroethyldiaminotriazine (Kd = 0.26) a...

  13. Environmental fate of the herbicide MCPA in agricultural soils amended with fresh and aged de-oiled two-phase olive mill waste.

    PubMed

    Peña, David; López-Piñeiro, Antonio; Albarrán, Ángel; Becerra, Daniel; Sánchez-Llerena, Javier

    2015-09-01

    Olive oil agrifood industry generates large amounts of waste whose recycling as organic amendment represents an alternative to their disposal. The impact of de-oiled two-phase olive mill waste (DW) on the fate of 4-chloro-2-methylphenoxyacetic acid (MCPA) in Mediterranean agricultural soils was evaluated. Furthermore, the effect of the transformation of organic matter from this waste under field conditions was assessed. Four Mediterranean agricultural soils were selected and amended in laboratory with fresh DW and field-aged DW (DW and ADW treatments, respectively). Adsorption capacity increased by factors between 1.18 and 3.59, for the DW-amended soils, and by factor of 4.93, for ADW-amended soil, with respect to unamended soils, when 5% amendment was applied. The DW amendment had inhibitory effect on dehydrogenase activity and slowed herbicide dissipation, whereas the opposite effect was observed in ADW treatments. In the field-amended soil, the amount of MCPA leached was significantly reduced from 56.9% for unamended soil to 15.9% at the 5% rate. However, leaching losses of MCPA increased in the laboratory-amended soils, because of their high water-soluble organic carbon values which could enhance MCPA mobility, especially in the acidic soils. Therefore, the application of DW as organic amendment in Mediterranean agricultural soils could be an important management strategy to reduce MCPA leaching, especially if the organic matter had been previously transformed by ageing processes. PMID:25948384

  14. Phytotoxicity and antioxidative enzymes of green microalga (Desmodesmus subspicatus) and duckweed (Lemna minor) exposed to herbicides MCPA, chloridazon and their mixtures.

    PubMed

    Bisewska, Joanna; Sarnowska, Emilia I; Tukaj, Zbigniew H

    2012-09-01

    In this study, we evaluate the toxicity of MCPA (auxin-like growth inhibitor), chloridazon (CHD) (PSII-inhibitor) and their mixtures to floating plants and planktonic algae. Toxicity of MCPA (4-chloro-2-methylphenoxyacetic acid) and CHD (5-amino-4-chloro-2-phenyl-3(2H)-pyridazinone) was first assessed in two growth inhibition tests with Lemna minor (ISO/DIS 20079) and Desmodesmus subspicatus (ISO 8692). Next, herbicide mixtures at concentrations corresponding to the EC values were used to assess their interactive effects, and the biomarkers were: for duckweed fresh weight, frond area, chlorophyll content and number of fronds, and for algae cell count and cell volume. The 3d EC₁₀ and EC₅₀ values using cell counts of D. subspicatus were 142.7 and 529.1 mg/L for MCPA and 1.7 and 5.1 mg/L for CHD. The 7d EC₁₀ and EC₅₀ values using frond number of L. minor amounted to 0.8 and 5.4 mg/L for MCPA and 0.7 and 10.4 mg/L for CHD. Higher sensitivity of reproductive (number of cells/fronds) than growth processes (cell volume/frond area) to herbicides applied individually and in mixtures was especially pronounced in the responses of Desmodesmus. Herbicide interactions were assessed by the two-way ANOVA and Abbott's formula. Generally, an antagonistic interaction with Lemna was revealed by MCPA and chloridazon, whereas additive effect of both herbicides was observed for Desmodesmus. A significant stimulation of SOD and APX activity by binary mixtures was noted in algal cells mainly after 24 and 48 hours of exposure. The extremely high stimulation of the activity of both enzymes was induced by the combination EC₁₀CHD + EC₅₀MCPA (48 h). Presumably due to oxidative stress, the treatment with CHD at concentration EC₅₀ after 72 h was lethal for algae grown in aerated cultures, in contrast to standardized test conditions. Taking into account the consequences of risk assessment for herbicide mixtures we can state that a relatively low toxicity, as well as the

  15. Influence of soil biochar aging on sorption of the herbicides MCPA, nicosulfuron, terbuthylazine, indaziflam, and fluoroethyldiaminotriazine.

    PubMed

    Trigo, Carmen; Spokas, Kurt A; Cox, Lucia; Koskinen, William C

    2014-11-12

    Sorption of four herbicides and a metabolite of indaziflam on a fresh macadamia nut biochar and biochars aged one or two years in soil was characterized. On fresh biochar, the sorption was terbuthylazine (Kd = 595) > indaziflam (Kd = 162) > MCPA (Kd = 7.5) > fluoroethyldiaminotriazine (Kd = 0.26) and nicosulfuron (Kd = 0). Biochar surface area increased with aging attributed to the loss of a surface film. This was also manifested in a decline in water extractable organic carbon with aging. Correspondingly, an increase in the aromaticity was observed. The higher surface area and porosity in aged biochar increased sorption of indaziflam (KdBC-2yr = 237) and fluoroethyldiaminotriazine (KdBC-1yr = 1.2 and KdBC-2yr = 3.0), but interestingly decreased sorption of terbuthylazine (KdBC-1yr = 312 and KdBC-2yr = 221) and MCPA (KdBC-1yr = 2 and KdBC-2yr = 2). These results will facilitate development of biochars for specific remediation purposes. PMID:25338136

  16. A review of potential human carcinogenicity of the chlorophenoxy herbicides MCPA, MCPP, and 2,4-DP.

    PubMed Central

    Bond, G G; Rossbacher, R

    1993-01-01

    For the purpose of assessing the human carcinogenic potential of the chlorophenoxy herbicides MCPA, MCPP, and 2,4-DP, the relevant epidemiological and toxicological evidence is reviewed. These compounds have not produced tumours in animal studies conducted under current test guidelines, giving no reason to predict that they would be carcinogenic to humans. Epidemiological studies have been conducted on three continents; greater emphasis is placed on the studies reported from western Europe, however, as this has been the area of more use. Although several of these studies provide suggestive evidence of associations between exposure to chlorophenoxy compounds and increased risks for some uncommon cancers, it is inconsistent and far from conclusive. None of the evidence specifically implicates MCPA, MCPP, or 2,4-DP as human carcinogens. PMID:8494774

  17. Layered double hydroxides as supports for the slow release of acid herbicides.

    PubMed

    Cardoso, Lucelena P; Celis, Rafael; Cornejo, Juan; Valim, João B

    2006-08-01

    A Mg/Al layered double hydroxide (LDH) was intercalated with the anionic herbicides 2,4-D, MCPA, and picloram by using three different methodologies: (i) direct synthesis (DS), (ii) regeneration (RE), and (iii) ion exchange (IE). The resulting complexes were characterized and assayed by batch release and column leaching tests, aiming at the controlled release of these herbicides. All the tested LDH-herbicide complexes displayed similar slow herbicide release properties in water, although the IE method seemed to result in complexes with a greater fraction of herbicide in a readily available form. Apparently, the LDH-herbicide complexes released most of the active ingredient present in the complexes at the end of the batch release experiment. This was attributed to the replacement of the intercalated herbicide by carbonate and hydroxyl anions from the aqueous solution. Compared to the free herbicides, the application of the three LDH-herbicide complexes (RE) to soil columns resulted in reduction in the maximum herbicide concentration in leachates and led to the retardation of herbicide leaching through the soil. All LDH-herbicide complexes presented an herbicidal efficacy similar to that of the free (technical) herbicides. Our results indicated the potential applicability of LDHs as supports for the preparation of slow release formulations of acid herbicides such as 2,4-D, MCPA, or picloram. PMID:16881703

  18. Effect of DDT and MCPA (4-chloro-2-methylphenoxyacetic acid) on reproduction of the pond snail, Lymnaea stagnalis L

    SciTech Connect

    Woin, P.; Broenmark, C. )

    1992-01-01

    Reproduction is the single most important function in the life cycle of an organism. Successful reproduction determines fitness of organisms. The inability of an organism to complete any one stage of the reproductive process severely reduces its lifetime reproductive success. Disruptions in the reproduction will ultimately affect the abundance and distribution of the species. Therefore, laboratory tests of long-term impact of sublethal pollutant concentrations on organisms preferably is done on the reproductive success. Pollutants of diverse structure may affect the reproductive system which is sensitive to toxic agents. Certain pollutants, notably the organochlorine compounds, have been shown to affect the male and female reproductive systems. The authors have studied the effect of sublethal concentrations of DDT and the herbicide 4-chloro-2-methylphenoxyacetic acid (MCPA) on the reproductive output of the pulmonate snail Lymnaea stagnalis under a 2-mon exposure period.

  19. Uptake of 4-chloro-2-methylphenoxyacetic acid (MCPA) from the apical membrane of Caco-2 cells by the monocarboxylic acid transporter

    SciTech Connect

    Kimura, Osamu; Tsukagoshi, Kensuke; Endo, Tetsuya

    2008-03-15

    The cellular uptake mechanism of 4-chloro-2-methylphenoxyacetic acid (MCPA), a phenoxyacetic acid derivative, was investigated using Caco-2 epithelial cells. The cells were incubated with 50 {mu}M MCPA at pH 6.0 and 37 deg. C, and the uptake of MCPA from the apical membranes was measured. The uptake of MCPA was significantly decreased by incubation at low temperature (4 {sup o}C) and markedly increased by lowering the extracellular pH. Pretreatment with a protonophore, carbonylcyanide-p-(trifluoromethoxy)phenylhydrazone (25 {mu}M), or metabolic inhibitors, 2,4-dinitrophenol (1 mM) and sodium azide (10 mM), significantly decreased the uptake of MCPA by 53%, 45% and 48%, respectively. Coincubation of MCPA with 10 mM L-lactic acid or {alpha}-cyano-4-hydroxycinnamate, which is a substrate or an inhibitor of the monocarboxylic acid transporters (MCTs), significantly decreased the uptake of MCPA by 31% and 20%, respectively, and coincubation with benzoic acid profoundly decreased the uptake by 68%. In contrast, coincubation with succinic acid (a dicarboxylic acid) did not affect the uptake. Kinetic analysis of initial MCPA uptake suggested that MCPA is taken up via a carrier-mediated process [K{sub m} = 1.37 {+-} 0.15 mM, V{sub max} = 115 {+-} 6 nmol (mg protein){sup -1} (3 min){sup -1}]. Lineweaver-Burk plots show that benzoic acid competitively inhibits the uptake of MCPA with a K{sub i} value of 4.68 {+-} 1.76 mM. A trans-stimulation effect on MCPA uptake was found in cells preloaded with benzoic acid. These results suggest that the uptake of MCPA from the apical membrane of Caco-2 cells is mainly mediated by common MCTs along with benzoic acid but also in part by L-lactic acid.

  20. The earthworm Aporrectodea caliginosa stimulates abundance and activity of phenoxyalkanoic acid herbicide degraders

    PubMed Central

    Liu, Ya-Jun; Zaprasis, Adrienne; Liu, Shuang-Jiang; Drake, Harold L; Horn, Marcus A

    2011-01-01

    2-Methyl-4-chlorophenoxyacetic acid (MCPA) is a widely used phenoxyalkanoic acid (PAA) herbicide. Earthworms represent the dominant macrofauna and enhance microbial activities in many soils. Thus, the effect of the model earthworm Aporrectodea caliginosa (Oligochaeta, Lumbricidae) on microbial MCPA degradation was assessed in soil columns with agricultural soil. MCPA degradation was quicker in soil with earthworms than without earthworms. Quantitative PCR was inhibition-corrected per nucleic acid extract and indicated that copy numbers of tfdA-like and cadA genes (both encoding oxygenases initiating aerobic PAA degradation) in soil with earthworms were up to three and four times higher than without earthworms, respectively. tfdA-like and 16S rRNA gene transcript copy numbers in soil with earthworms were two and six times higher than without earthworms, respectively. Most probable numbers (MPNs) of MCPA degraders approximated 4 × 105 gdw−1 in soil before incubation and in soil treated without earthworms, whereas MPNs of earthworm-treated soils were approximately 150 × higher. The aerobic capacity of soil to degrade MCPA was higher in earthworm-treated soils than in earthworm-untreated soils. Burrow walls and 0–5 cm depth bulk soil displayed higher capacities to degrade MCPA than did soil from 5–10 cm depth bulk soil, expression of tfdA-like genes in burrow walls was five times higher than in bulk soil and MCPA degraders were abundant in burrow walls (MPNs of 5 × 107 gdw−1). The collective data indicate that earthworms stimulate abundance and activity of MCPA degraders endogenous to soil by their burrowing activities and might thus be advantageous for enhancing PAA degradation in soil. PMID:20740027

  1. Evidence for the importance of litter as a co-substrate for MCPA dissipation in an agricultural soil.

    PubMed

    Saleh, Omar; Pagel, Holger; Enowashu, Esther; Devers, Marion; Martin-Laurent, Fabrice; Streck, Thilo; Kandeler, Ellen; Poll, Christian

    2016-03-01

    Environmental controls of 2-methyl-4-chlorophenoxyacetic acid (MCPA) degradation are poorly understood. We investigated whether microbial MCPA degraders are stimulated by (maize) litter and whether this process depends on concentrations of MCPA and litter. In a microcosm experiment, different amounts of litter (0, 10 and 20 g kg(-1)) were added to soils exposed to three levels of the herbicide (0, 5 and 30 mg kg(-1)). The treated soils were incubated at 20 °C for 6 weeks, and samples were taken after 1, 3 and 6 weeks of incubation. In soils with 5 mg kg(-1) MCPA, about 50 % of the MCPA was dissipated within 1 week of the incubation. Almost complete dissipation of the herbicide had occurred by the end of the incubation with no differences between the three litter amendments. At the higher concentration (30 mg kg(-1)), MCPA endured longer in the soil, with only 31 % of the initial amount being removed at the end of the experiment in the absence of litter. Litter addition greatly increased the dissipation rate with 70 and 80 % of the herbicide being dissipated in the 10 and 20 g kg(-1) litter treatments, respectively. Signs of toxic effects of MCPA on soil bacteria were observed from related phospholipid fatty acid (PLFA) analyses, while fungi showed higher tolerance to the increased MCPA levels. The abundance of bacterial tfdA genes in soil increased with the co-occurrence of litter and high MCPA concentration, indicating the importance of substrate availability in fostering MCPA-degrading bacteria and thereby improving the potential for removal of MCPA in the environment. PMID:25943518

  2. MCPA permeation through protective gloves.

    PubMed

    Purdham, J T; Menard, B J; Bozek, P R; Sass-Kortsak, A M

    2001-10-01

    Permeation of 4-chloro-2-methylphenoxyacetic acid (MCPA) in commercial herbicide formulations through common protective glove types was evaluated to aid in the selection of appropriate skin protection. The ASTM test method F739-91 was used to measure the permeation of two undiluted formulations, one containing a salt, and the other an ester form of MCPA. The four glove types tested were natural rubber, neoprene 73, nitrile 37-145, and Viton-coated chloroprene. Triplicate tests of each combination of formulation and glove material were conducted. Permeation cells with a 0.01 M sodium hydroxide collection medium were used for the experiments. Aliquots of the collection medium were withdrawn at regular intervals and acidified, and quantification of the free acid was achieved using HPLC-UV (230 nm). There was no appreciable permeation of the salt formulation over a 24-hour test period. For the ester formulation, the following mean steady-state permeation rate (microg x cm(-2) min(-1)) and mean lag time (hours), respectively, were measured: Viton (0.06, 17.8), natural rubber (0.08, 15.4), neoprene 73 (0.21, 15.1), and nitrile (0.04, 24.2). Permeation was associated with significant swelling, averaging a nearly 30 percent increase from the pre-immersion thickness. All four glove types provide adequate protection against permeation by the salt formulation and at least eight-hour protection against the ester formulation. Given the greater permeation of the ester formulation, the salt formulation of MCPA herbicide should be used whenever possible. PMID:11599545

  3. Adsorption and degradation of phenoxyalkanoic acid herbicides in soils: A review.

    PubMed

    Paszko, Tadeusz; Muszyński, Paweł; Materska, Małgorzata; Bojanowska, Monika; Kostecka, Małgorzata; Jackowska, Izabella

    2016-02-01

    The primary aim of the present review on phenoxyalkanoic acid herbicides-2-(2,4-dichlorophenoxy) acetic acid (2,4-D), 2-(4-chloro-2-methylphenoxy) acetic acid (MCPA), (2R)-2-(2,4-dichlorophenoxy) propanoic acid (dichlorprop-P), (2R)-2-(4-chloro-2-methylphenoxy) propanoic acid (mecoprop-P), 4-(2,4-dichlorophenoxy) butanoic acid (2,4-DB), and 4-(4-chloro-2-methylphenoxy) butanoic acid (MCPB)-was to compare the extent of their adsorption in soils and degradation rates to assess their potential for groundwater contamination. The authors found that adsorption decreased in the sequence of 2,4-DB > 2,4-D > MCPA > dichlorprop-P > mecoprop-P. Herbicides are predominantly adsorbed as anions-on organic matter and through a water-bridging mechanism with adsorbed Fe cations-and their neutral forms are adsorbed mainly on organic matter. Adsorption of anions of 2,4-D, MCPA, dichlorprop-P, and mecoprop-P is inversely correlated with their lipophilicity values, and modeling of adsorption of the compounds based on this relationship is possible. The predominant dissipation mechanism of herbicides in soils is bacterial degradation. The contribution of other mechanisms, such as degradation by fungi, photodegradation, or volatilization from soils, is much smaller. The rate of bacterial degradation decreased in the following order: 2,4-D > MCPA > mecoprop-P > dichlorprop-P. It was found that 2,4-D and MCPA have the lowest potential for leaching into groundwater and that mecoprop-P and dichlorprop-P have slightly higher potential. Because of limited data on adsorption and degradation of 2,4-DB and MCPB, estimation of their leaching potential was not possible. PMID:26292078

  4. Adsorption and characterization of MCPA on DDTMA- and raw-montmorillonite: Surface sites involved.

    PubMed

    Santiago, Cintia C; Fernández, Mariela A; Torres Sánchez, Rosa M

    2016-01-01

    The 4-chloro-2-methylphenoxy acid (MCPA) is an herbicide widely used in agriculture, which generates a great concern about contamination of surface water and serious consequences for human health and the environment. In this work, the adsorption of MCPA on an Argentine montmorillonite (MMT) and its organo-montmorillonite product (OMMT) with different dodecyl trimethyl ammonium loading was investigated. MCPA adsorption on OMMT increases at least 3 times, with respect to the amount determined for MMT. X-ray diffraction and zeta potential analyses indicated the inner (interlayer) and outer surface participate as adsorption sites. Changes in surface electric charge and also interlayer expansion suggest that dimethyl amine (MCPA counterion) was also surface-adsorbed. The larger aggregates of OMMT, without and with MCPA, obtained compared to those of MMT samples, generate an improvement in the coagulation efficiency. This property, particularly after MCPA retention, allows an easier separation of the solids from the solution and enables a simple technological process application. PMID:26786275

  5. Behavior of MCPA in four intensive cropping soils amended with fresh, composted, and aged olive mill waste

    NASA Astrophysics Data System (ADS)

    López-Piñeiro, Antonio; Peña, David; Albarrán, Angel; Sánchez-Llerena, Javier; Becerra, Daniel

    2013-09-01

    An evaluation was made of the impact of olive mill waste and its organic matter transformation on the sorption, desorption, leaching, and degradation of the herbicide MCPA when the waste was applied to four Mediterranean soils. The soils were amended in the laboratory with fresh, composted, and field-aged olive mill waste (OW, COW, and AOW treatments, respectively). It was found that the greater the amount of OW applied to the soils, but especially the greater its organic matter maturity, the greater the adsorption of MCPA. Compared with unamended soils, at the 5% rate of application the adsorption capacity increased by between 9.8% and 40%, 148% and 224%, and by 258% for the OW, COW, and AOW amended soils, respectively. The hysteresis coefficients were significantly lower in the OW-amended soils than in AOW or COW-amended soils, indicating that the adsorbed MCPA could be easily desorbed in OW-amended soils if the amendment is not aged or composted. While the OW addition greatly extended the persistence of MCPA, the application of COW enhanced MCPA degradation in all the soils, as corresponded to the increased soil microbial activity indicated by the higher levels of soil dehydrogenase activity. Fresh OW amendment significantly increased the amount of MCPA leached (from 13.7% in the most alkaline soil to 36.7% in the most acidic, at the 5% rate of application), favored by the higher levels of water soluble organic carbon content. However, leaching losses of the herbicide were reduced by up to 39.9% and 55.3% in the COW- and AOW-amended soils at the 5% loading rate, respectively. The use of OW with a high degree of organic matter maturity may be regarded as a potentially useful management practice to reduce MCPA leaching in soils with low organic matter content. The application of fresh OW, however, could well increase the risk of groundwater contamination by this herbicide, especially in acidic soils.

  6. Cm-scale Heterogeneity in Degradation - Potential Impact on Leaching of MCPA through a Variably-Saturated Macroporous Clayey Till

    NASA Astrophysics Data System (ADS)

    Rosenbom, A. E.; Johnsen, A. R.; Aamand, J.; Binning, P. J.; Dechesne, A.; Smets, B. F.; "Cream-Spatial Heterogeneity"-Team

    2011-12-01

    Recent research has revealed a large variation in pesticide mineralization potentials, but little is known about the scale at which these heterogeneities impact the spreading of contaminants. A modeling study aiming at quantifying how heterogeneous degradation potentials in agricultural soil will affect MCPA degradation and leaching was conducted. 2D-distributions (96-well micro plate mineralization assay) of the mineralization potentials of phenoxy acid herbicides (MCPA, 2,4-D) representing layers in the upper meter of variably-saturated clayey till were applied. The rapid mineralization measured was represented by Monod mineralization kinetics, whereas the rest were either represented by slow 0-order mineralization kinetics or no degradation. Five 3D-modelling scenarios were set up using the COMSOL Multiphysics 4.1 toolbox (COMSOL Inc., Burlington, MA, USA): 1) simple matrix flow of water with no biodegradation of the MCPA at all nodes; 2) preferential flow (including a wormhole) of water with no biodegradation of the MCPA at all nodes; 3) simple matrix flow of water with average biodegradation of the MCPA at all nodes, which corresponds to results derived from a conventional homogenized soil sample; 4) simple matrix flow of water with the observed high variation in biodegradation of the MCPA corresponding to random variation in degradation; and 5) vertical structure in water flow combined with vertically structured degradation (defined hot spots and cold spots), which corresponds to a situation where both flow and degradation are associated with macropores/wormholes. Results show that cm-scale heterogeneity in degradation potential with simple matrix flow has a negligible effect on MCPA leaching at one meter below soil surface. By introducing a wormhole in the low-permeable 3D-soil modeling domain, however, the risk of MCPA-leaching below one meter depth increase drastically with low degradation potential along the wall of macropores/wormholes.

  7. Isotope dilution high-resolution gas chromatography/high-resolution mass spectrometry method for analysis of selected acidic herbicides in surface water.

    PubMed

    Woudneh, Million B; Sekela, Mark; Tuominen, Taina; Gledhill, Melissa

    2006-11-10

    In this work, an isotope dilution method for determination of selected acidic herbicides by high-resolution gas chromatography/high-resolution mass spectrometry (HRGC/HRMS) was developed for surface water samples. Average percent recoveries of native analytes were observed to be between 70.8 and 93.5% and average recoveries of labeled quantification standards [(13)C(6)]2,4-D and [(13)C(6)]2,4,5-T were 85.5 and 101%, respectively. Using this method, detection limits of 0.05 ng/L for dicamba, MCPA, MCPP, and triclopyr, and 0.5 ng/L for 2,4-D were routinely achieved. The method was applied to measuring the concentration of these analytes in surface water samples collected from five sampling locations in the Lower Fraser Valley region of British Columbia, Canada. All of the herbicides monitored were detected at varying levels in the surface water samples collected. The highest concentrations detected for each analyte were 345 ng/L for 2,4-D, 317 ng/L for MCPA, 271 ng/L for MCPP, 15.7 ng/L for dicamba, and 2.18 ng/L for triclopyr. Average detection frequencies of the herbicides were 95% for MCPA, 80% for MCPP, 70% for dicamba, 65% for 2,4-D, and 46% for triclopyr. Seasonal variations of herbicide levels are also discussed. PMID:16956613

  8. 40 CFR 180.318 - 4-(2-Methyl-4-chlorophenoxy) butyric acid; tolerance for residues.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... established for the combined residues, free and conjugated, of the herbicide MCPB, 4-(4-chloro-2-methylphenoxy)butanoic acid, and its metabolite MCPA, (4-chloro-2-methylphenoxy)acetic acid, in or on the following...

  9. Assessment of Envi-Carb™ as a passive sampler binding phase for acid herbicides without pH adjustment.

    PubMed

    Seen, Andrew; Bizeau, Oceane; Sadler, Lachlan; Jordan, Timothy; Nichols, David

    2014-05-01

    The graphitised carbon solid phase extraction (SPE) sorbent Envi-Carb has been used to fabricate glass fibre filter- Envi-Carb "sandwich" disks for use as a passive sampler for acid herbicides. Passive sampler uptake of a suite of herbicides, including the phenoxyacetic acid herbicides 4-chloro-o-tolyloxyacetic acid (MCPA), 2,4-dichlorophenoxyacetic acid (2,4-D) and 3,6-dichloro-2-methoxybenzoic acid (Dicamba), was achieved without pH adjustment, demonstrating for the first time a suitable binding phase for passive sampling of acid herbicides at neutral pH. Passive sampling experiments with Duck River (Tasmania, Australia) water spiked at 0.5 μg L(-1) herbicide concentration over a 7 d deployment period showed that sampling rates in Duck River water decreased for seven out of eight herbicides, and in the cases of 3,6-dichloro-2-pyridinecarboxylic acid (Clopyralid) and Dicamba no accumulation of the herbicides occurred in the Envi-Carb over the deployment period. Sampling rates for 4-amino-3,5,6-trichloro-2-pyridinecarboxylic acid (Picloram), 2,4-D and MCPA decreased to approximately 30% of the sampling rates in ultrapure water, whilst sampling rates for 2-(4,6-dimethylpyrimidin-2-ylcarbamoylsulfamoyl) benzoic acid, methyl ester (Sulfometuron-methyl) and 3,5,6-Trichloro-2-pyridinyloxyacetic acid (Triclopyr) were approximately 60% of the ultrapure water sampling rate. For methyl N-(2,6-dimethylphenyl)-N-(methoxyacetyl)-D-alaninate (Metalaxyl-M) there was little variation in sampling rate between passive sampling experiments in ultrapure water and Duck River water. SPE experiments undertaken with Envi-Carb disks using ultrapure water and filtered and unfiltered Duck River water showed that not only is adsorption onto particulate matter in Duck River water responsible for a reduction in herbicide sampling rate, but interactions of herbicides with dissolved or colloidal matter (matter able to pass through a 0.2 μm membrane filter) also reduces the herbicide sampling

  10. Toxicokinetics, including saturable protein binding, of 4-chloro-2-methyl phenoxyacetic acid (MCPA) in patients with acute poisoning.

    PubMed

    Roberts, Darren M; Dawson, Andrew H; Senarathna, Lalith; Mohamed, Fahim; Cheng, Ron; Eaglesham, Geoffrey; Buckley, Nick A

    2011-03-25

    Human data on protein binding and dose-dependent changes in toxicokinetics for MCPA are very limited. 128 blood samples were obtained in 49 patients with acute MCPA poisoning and total and unbound concentrations of MCPA were determined. The Scatchard plot was biphasic suggesting protein binding to two sites. The free MCPA concentration increased when the total concentration exceeded 239mg/L (95% confidence interval 198-274mg/L). Nonlinear regression using a two-site binding hyperbola model estimated saturation of the high affinity binding site at 115mg/L (95%CI 0-304). Further analyses using global fitting of serial data and adjusting for the concentration of albumin predicted similar concentrations for saturable binding (184mg/L and 167mg/L, respectively) without narrowing the 95%CI. In 25 patients, the plasma concentration-time curves for both bound and unbound MCPA were approximately log-linear which may suggest first order elimination, although sampling was infrequent so zero order elimination cannot be excluded. Using a cut-off concentration of 200mg/L, the half-life of MCPA at higher concentrations was 25.5h (95%CI 15.0-83.0h; n=16 patients) compared to 16.8h (95%CI 13.6-22.2h; n=10 patients) at lower concentrations. MCPA is subject to saturable protein binding but the influence on half-life appears marginal. PMID:21256202

  11. Suicidal poisoning by MCPA and parathion.

    PubMed

    De Beer, J; Heyndrickx, A; Van Peteghem, C; Piette, M; Timperman, J

    1980-01-01

    A suicidal poisoning committed by a sixty-five year old woman, who swallowed a bottle of Agroxyl, containing an aqueous 250 g/L solution of the sodium- and potassium salt of 2-methyl-4-chlorophenoxyacetic acid [MCPA], together with lethal amounts of a parathion formulation, is described. The case history, the postmortem examination and the concentrations of parathion and MCPA in the different viscera, are reported in detail. Parathion determination was performed by means of a routine method, previously developed in our laboratory. The MCPA quantification was achieved using a thoroughly evaluated EC- GLC micro-analytical procedure, which is discussed completely. Identity was confirmed by GC-MS. Intake of lethal parathion quantities caused the woman's death with five minutes. This case however is worth reporting, since we had the unique opportunity to establish the early distribution of MCPA through the body, during the short period of survival. PMID:7421141

  12. Comparative Inter-Species Pharmacokinetics of Phenoxyacetic Acid Herbicides and Related Organic Acids. Evidence that the Dog is Not a Relevant Species for Evaluation of Human Health Risk.

    SciTech Connect

    Timchalk, Chuck

    2004-07-15

    Phenoxyacetic acids including 2,4-dichlorophenoxyacetic acid (2,4-D) and 4-chloro-2-methylphenoxyacetic acid (MCPA) are widely utilized organic acid herbicides that have undergone extensive toxicity and pharmacokinetic analyses. The dog is particularly susceptible to the toxicity of phenoxyacetic acids and related organic acids relative to other species. Active renal clearance mechanisms for organic acids are ubiquitous in mammalian species, and thus a likely mechanism responsible for the increased sensitivity of the dog to these agents is linked to a lower capacity to secrete organic acids from the kidney. Using published data describing the pharmacokinetics of phenoxyacetic and structurally related organic acids in a variety of species including humans, inter-species comparative pharmacokinetics were evaluated using allometic parameter scaling. For both 2,4-D and MCPA the dog plasma half-life (t1/2) and renal clearance (Clr; ml hr-1) rates did not scale as a function of body weight across species; whereas for all other species evaluated, including humans, these pharmacokinetic parameters reasonably scaled. This exceptional response in the dog is clearly illustrated by comparing the plasma t1/2 at comparable doses of 2,4-D and MCPA, across several species. At a dosage of 5 mg/kg, in dogs the plasma t1/2 for 2,4-D and MCPA were {approx}92 - 106 hr and 63 hr, respectively, which is substantially longer than in the rat ({approx}1 and 6 hr, respectively) or in humans (12 and 11 hr, respectively). This longer t1/2, and slower elimination in the dog, results in substantially higher body burdens of these organic acids, at comparable doses, relative to other species. Although these results indicate the important role of renal transport clearance mechanisms as determinants of the clearance and potential toxicity outcomes of phenoxyacetic acid herbicides across several species, other contributing mechanisms such as reabsorption from the renal tubules is highly likely. These

  13. PHENOXYALKANOIC ACID HERBICIDES IN MUNICIPAL LANDFILL LEACHATES

    EPA Science Inventory

    Analysis of leachates from six U.S. municipal landfills revealed the presence of chlorinated 2-phenoxypropionic acid herbicides; however, none of the more widely used acetic acid analogues was present at quantifiable levels. ll of the leachates contained MCPP. ,4-DP and silvex we...

  14. Influence of oligomeric herbicidal ionic liquids with MCPA and Dicamba anions on the community structure of autochthonic bacteria present in agricultural soil.

    PubMed

    Ławniczak, Ł; Syguda, A; Borkowski, A; Cyplik, P; Marcinkowska, K; Wolko, Ł; Praczyk, T; Chrzanowski, Ł; Pernak, J

    2016-09-01

    The aim of this study was to evaluate the impact of selected herbicidal ionic liquids (HILs), which exhibit high efficacy in terms of weed control and low toxicity, but may be persistent due to limited biodegradability, on the community structure of autochthonic bacteria present in agricultural soil. Four different oligomeric HILs (with two types of cations and different ratio of herbicidal anions) were synthesized and characterized by employing (1)H and (13)C NMR. The results of biodegradation assay indicated that none of the tested HILs could be classified as readily biodegradable (biodegradation rate ranged from 0 to 7%). The conducted field studies confirmed that the herbicidal efficacy of the HILs was higher compared to the reference herbicide mixture by 10 to 30%, depending on the dose and weed species. After termination of field studies, the soil treated with the tested HILs was subjected to next generation sequencing in order to investigate the potential changes in the bacterial community structure. Proteobacteria was the dominant phylum in all studied samples. Treatment with the studied HILs resulted in an increase of Actinobacteria compared to the reference herbicidal mixture. Differenced among the studied HILs were generally associated with a significantly higher abundance of Bacteroidetes in case of 1-HIL-Dicamba 1/3 and Firmicutes in case of 2-HIL-Dicamba 1/3. PMID:27135587

  15. Comparing Metabolic Functionalities, Community Structures, and Dynamics of Herbicide-Degrading Communities Cultivated with Different Substrate Concentrations

    PubMed Central

    Gözdereliler, Erkin; Boon, Nico; Aamand, Jens; De Roy, Karen; Granitsiotis, Michael S.; Albrechtsen, Hans-Jørgen

    2013-01-01

    Two 4-chloro-2-methylphenoxyacetic acid (MCPA)-degrading enrichment cultures selected from an aquifer on low (0.1 mg liter−1) or high (25 mg liter−1) MCPA concentrations were compared in terms of metabolic activity, community composition, population growth, and single cell physiology. Different community compositions and major shifts in community structure following exposure to different MCPA concentrations were observed using both 16S rRNA gene denaturing gradient gel electrophoresis fingerprinting and pyrosequencing. The communities also differed in their MCPA-mineralizing activities. The enrichments selected on low concentrations mineralized MCPA with shorter lag phases than those selected on high concentrations. Flow cytometry measurements revealed that mineralization led to cell growth. The presence of low-nucleic acid-content bacteria (LNA bacteria) was correlated with mineralization activity in cultures selected on low herbicide concentrations. This suggests that LNA bacteria may play a role in degradation of low herbicide concentrations in aquifers impacted by agriculture. This study shows that subpopulations of herbicide-degrading bacteria that are adapted to different pesticide concentrations can coexist in the same environment and that using a low herbicide concentration enables enrichment of apparently oligotrophic subpopulations. PMID:23124226

  16. Determination of chlorinated acid herbicides in vegetation and soil by liquid chromatography/electrospray-tandem mass spectrometry.

    PubMed

    Schaner, Angela; Konecny, Jaclyn; Luckey, Laura; Hickes, Heidi

    2007-01-01

    The method presented uses reversed-phase liquid chromatography with negative electrospray ionization and tandem mass spectrometry to analyze 9 chlorinated acid herbicides in soil and vegetation matrixes: clopyralid, dicamba, MCPP, MCPA, 2,4-DP, 2,4-D, triclopyr, 2,4-DB, and picloram. A 20 g portion is extracted with a basic solution and an aliquot acidified and micropartitioned with 3 mL chloroform. Vegetation samples are subjected to an additional cleanup with a mixed-mode anion exchange solid-phase extraction cartridge. Two precursor product ion transitions per analyte are measured and evaluated to provide the maximum degree of confidence in results. Average recoveries for 3 different soil types tested ranged from 72 to 107% for all compounds with the exception of 2,4-DB at 56-99%. Average recoveries for the 3 different vegetation types studied were lower and ranged from 53 to 80% for all compounds. PMID:17955986

  17. Oxidative degradation of different chlorinated phenoxyalkanoic acid herbicides by a hybrid ZrO2 gel-derived catalyst without light irradiation.

    PubMed

    Sannino, Filomena; Pernice, Pasquale; Minieri, Luciana; Camandona, Gaia Aurora; Aronne, Antonio; Pirozzi, Domenico

    2015-01-14

    The oxidative degradation of 2-methyl-4-chlorophenoxyacetic acid (MCPA), 4-(4-chloro-2-methylphenoxy)butanoic acid (MCPB), 4-chlorophenoxyacetic acid (4-CPA) and 2,4-dichlorophenoxyacetic acid (2,4 D) by ZrO2-acetylacetonate hybrid catalyst (HSGZ) without light irradiation was assessed. The thermal stability of the catalyst was investigated by thermogravimetry, differential thermal analysis, and Fourier transform infrared spectroscopy. For each herbicide, a virtually complete removal in about 3 days without light irradiation at room temperature was achieved. The removal kinetics of the herbicides has been satisfactorily characterized by a double-stage physico-mathematical model, in the hypothesis that a first-order adsorption on HSGZ surface is followed by the herbicide degradation, catalytically driven by HSGZ surface groups. The long-term use of the HSGZ catalyst was assessed by repeated-batch tests. The specific cost for unit-volume removal of herbicide was evaluated by a detailed cost analysis showing that it is comparable with those pertaining to alternative methods. PMID:25479367

  18. Pelargonic acid as a herbicide in sweet bell peppers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pelargonic acid, although not certified as organic, is naturally occurring in many plants, animals, and foods. It is also phytotoxic to plants as a contact herbicide, injuring and killing plants by destroying the cell membrane. Vegetable producers would benefit from additional herbicide options tha...

  19. Betaine and Carnitine Derivatives as Herbicidal Ionic Liquids.

    PubMed

    Pernak, Juliusz; Niemczak, Michał; Chrzanowski, Łukasz; Ławniczak, Łukasz; Fochtman, Przemysław; Marcinkowska, Katarzyna; Praczyk, Tadeusz

    2016-08-16

    This study focused on the synthesis and subsequent characterization of herbicidal ionic liquids based on betaine and carnitine, two derivatives of amino acids, which were used as cations. Four commonly used herbicides (2,4-D, MCPA, MCPP and Dicamba) were used as anions in simple (single anion) and oligomeric (two anions) salts. The obtained salts were subjected to analyzes regarding physicochemical properties (density, viscosity, refractive index, thermal decomposition profiles and solubility) as well as evaluation of their herbicidal activity under greenhouse and field conditions, toxicity towards rats and biodegradability. The obtained results suggest that the synthesized herbicidal ionic liquids displayed low toxicity (classified as category 4 compounds) and showed similar or improved efficacy against weed compared to reference herbicides. The highest increase was observed during field trials for salts containing 2,4-D as the anion, which also exhibited the highest biodegradability (>75 %). PMID:27374836

  20. Sorption and leaching potential of acidic herbicides in Brazilian soils.

    PubMed

    Spadotto, Claudio A; Hornsby, Arthur G; Gomes, Marco A F

    2005-01-01

    Leaching of acidic herbicides (2,4-D, flumetsulam, and sulfentrazone) in soils was estimated by comparing the original and modified AF (Attenuation Factor) models for multi-layered soils (AFi). The original AFi model was modified to include the concept of pH-dependence for Kd (sorption coefficient) based on pesticide dissociation and changes in the accessibility of soil organic functional groups able to interact with the pesticide. The original and modified models, considering soil and herbicide properties, were applied to assess the leaching potential of selected herbicides in three Brazilian soils. The pH-dependent Kd values estimated for all three herbicides were observed to be always higher than pH-independent Kd values calculated using average Koc data, and therefore the original AFi model overestimated the overall leaching potential for the soils studied. PMID:15656159

  1. Proteolytic Pathways Induced by Herbicides That Inhibit Amino Acid Biosynthesis

    PubMed Central

    Zulet, Amaia; Gil-Monreal, Miriam; Villamor, Joji Grace; Zabalza, Ana; van der Hoorn, Renier A. L.; Royuela, Mercedes

    2013-01-01

    Background The herbicides glyphosate (Gly) and imazamox (Imx) inhibit the biosynthesis of aromatic and branched-chain amino acids, respectively. Although these herbicides inhibit different pathways, they have been reported to show several common physiological effects in their modes of action, such as increasing free amino acid contents and decreasing soluble protein contents. To investigate proteolytic activities upon treatment with Gly and Imx, pea plants grown in hydroponic culture were treated with Imx or Gly, and the proteolytic profile of the roots was evaluated through fluorogenic kinetic assays and activity-based protein profiling. Results Several common changes in proteolytic activity were detected following Gly and Imx treatment. Both herbicides induced the ubiquitin-26 S proteasome system and papain-like cysteine proteases. In contrast, the activities of vacuolar processing enzymes, cysteine proteases and metacaspase 9 were reduced following treatment with both herbicides. Moreover, the activities of several putative serine protease were similarly increased or decreased following treatment with both herbicides. In contrast, an increase in YVADase activity was observed under Imx treatment versus a decrease under Gly treatment. Conclusion These results suggest that several proteolytic pathways are responsible for protein degradation upon herbicide treatment, although the specific role of each proteolytic activity remains to be determined. PMID:24040092

  2. Exposure to phenoxyacetic acid herbicides and predictors of exposure among spouses of farmers.

    PubMed

    Jurewicz, Joanna; Hanke, Wojciech; Sobala, Wojciech; Ligocka, Danuta

    2012-01-01

    The purpose of the study was to assess the environmental exposure to 2 commonly used pesticides: 2-methyl-4- chlorophenoxyacetic acid (MCPA) and 2,4-dichlorophenoxyacetic acid (2,4-D) among spouses of farmers, not directly involved in the process of spraying. Exposure to 63 sprayings 24 women in households from the rural area of the Łódż Voivodeship in Poland was assessed. The women were asked to collect 3 biological urine samples: in the morning before spraying (sample A), in the evening after spraying (sample B), and on the morning of the next day (sample C). The determination of pesticides in urine was performed by high performance liquid chromatography, coupled with tandem mass spectrometry and negative electrospray (LC-MS/MS-ESI-). In the case of both active ingredient, the number of urine samples with the level of pesticides above limit of detection (LOD) increased from 30% in samples A to 45% in samples B and C. The average levels of herbicides increased from sample A (2.8 ng/g creatinine) to sample B (6.0 ng/g creatinine). The mean value of the C sample was 4.0 ng/g creatinine. Similar results were obtained when the average was calculated for all measurements, including those below LOD. The outdoor activity of the women during spraying was statistically significant (p=0.023), a predictor of exposure in multivariate analyses. The presented study indicates that farmers' spouses might be exposed to pesticides, even if they do not take part in the spraying. PMID:22462445

  3. A Systematic Review of Carcinogenic Outcomes and Potential Mechanisms from Exposure to 2,4-D and MCPA in the Environment

    PubMed Central

    von Stackelberg, Katherine

    2013-01-01

    Chlorophenoxy compounds, particularly 2,4-dichlorophenoxyacetic acid (2,4-D) and 4-chloro-2-methylphenoxy)acetic acid (MCPA), are amongst the most widely used herbicides in the United States for both agricultural and residential applications. Epidemiologic studies suggest that exposure to 2,4-D and MCPA may be associated with increased risk non-Hodgkins lymphoma (NHL), Hodgkin's disease (HD), leukemia, and soft-tissue sarcoma (STS). Toxicological studies in rodents show no evidence of carcinogenicity, and regulatory agencies worldwide consider chlorophenoxies as not likely to be carcinogenic or unclassifiable as to carcinogenicity. This systematic review assembles the available data to evaluate epidemiologic, toxicological, pharmacokinetic, exposure, and biomonitoring studies with respect to key cellular events noted in disease etiology and how those relate to hypothesized modes of action for these constituents to determine the plausibility of an association between exposure to environmentally relevant concentrations of 2,4-D and MCPA and lymphohematopoietic cancers. The combined evidence does not support a genotoxic mode of action. Although plausible hypotheses for other carcinogenic modes of action exist, a comparison of biomonitoring data to oral equivalent doses calculated from bioassay data shows that environmental exposures are not sufficient to support a causal relationship. Genetic polymorphisms exist that are known to increase the risk of developing NHL. The potential interaction between these polymorphisms and exposures to chlorophenoxy compounds, particularly in occupational settings, is largely unknown. PMID:23533401

  4. Toxicity of chlorinated phenoxyacetic acid herbicides in the experimental eukaryotic model Saccharomyces cerevisiae: role of pH and of growth phase and size of the yeast cell population.

    PubMed

    Cabral, M G; Viegas, C A; Teixeira, M C; Sá-Correia, I

    2003-04-01

    The inhibitory effect of the herbicides 2-methyl-4-chlorophenoxyacetic acid (MCPA) and 2,4-dichlorophenoxyacetic acid (2,4-D) in Saccharomyces cerevisiae growth is strongly dependent on medium pH (range 2.5-6.5). Consistent with the concept that the toxic form is the liposoluble undissociated form, at values close to their pK(a) (3.07 and 2.73, respectively) the toxicity is high, decreasing with the increase of external pH. In addition, the toxicity of identical concentrations of the undissociated acid form is pH independent, as observed with 2,4-dichlorophenol (2,4-DCP), an intermediate of 2,4-D degradation. Consequently, at pH values above 3.5 (approximately one unit higher than 2,4-D pK(a)), 2,4-DCP becomes more toxic than the original herbicide. A dose-dependent inhibition of growth kinetics and increased duration of growth latency is observed following sudden exposure of an unadapted yeast cell population to the presence of the herbicides. This contrasts with the effect of 2,4-DCP, which essentially affects growth kinetics. Experimental evidences suggest that the acid herbicides toxicity is not exclusively dependent on the liposolubility of the toxic form, as may essentially be the case of 2,4-DCP. An unadapted yeast cell population at the early stationary-phase of growth under nutrient limitation is significantly more resistant to short-term herbicide induced death than an exponential-phase population. Consequently, the duration of growth latency is reduced, as observed with the increase of the size of the herbicide stressed population. However, these physiological parameters have no significant effect either on growth kinetics, following growth resumption under herbicide stress, or on the growth curve of yeast cells previously adapted to the herbicides, indicating that their role is exerted at the level of cell adaptation. PMID:12586155

  5. Passive extraction and clean-up of phenoxy acid herbicides in samples from a groundwater plume using hollow fiber supported liquid membranes.

    PubMed

    Liu, Jing-Fu; Toräng, Lars; Mayer, Philipp; Jönsson, Jan Ake

    2007-08-10

    Hollow fiber supported liquid membranes were applied for the passive extraction of phenoxy acid herbicides from water samples. Polypropylene hollow fiber membranes (240 microm i.d., 30 microm wall thickness, 0.05 microm pore size, 30 cm length) were impregnated with 2.0% tri-n-octylphosphine oxide (TOPO) in di-n-hexyl ether in the pores of the fiber wall to form a liquid membrane. They were then filled with basic solution in the lumen as acceptor and finally placed into the sample (donor). Complete extraction of phenoxy acid herbicides including 2,4-D, MCPA, dichlorprop, and mecoprop from an acidified sample (4 mL, adjusted to pH 1.5 with HCl) into basic acceptor (10 microL of 0.2M NaOH) was achieved after 4 h of shaking (100 rpm) resulting in an enrichment factor of 400 times. The acceptor was then neutralized by addition of HCl and injected into a HPLC system for the determination of the phenoxy acid herbicides. Environmentally relevant salinity (0-3.5% NaCl) and dissolved organic matter (0-25 mg/L of dissolved organic carbon) had no significant effect on the extraction. The method provided extraction efficiencies of more than 91%, detection limits of 0.3-0.6 microg/L, and combined extraction and clean up in one single step. This procedure was applied to determine aqueous concentrations of phenoxy acid herbicides in groundwater samples collected from an old dumping site (Cheminova, Denmark) with detected concentrations up to 5800 microg/L. Although the samples were very dirty with large amounts of suspended particles, non-aqueous phase liquids (NAPLs) and dissolved organic matters, good spike recoveries (80-126%) were obtained for 10 of the 11 samples. PMID:17449052

  6. Determination of acidic herbicides in cereals by QuEChERS extraction and LC/MS/MS.

    PubMed

    Santilio, Angela; Stefanelli, Patrizia; Girolimetti, Silvana; Dommarco, Roberto

    2011-01-01

    A simple and rapid method has been studied for the determination of acidic herbicides (2,4-D, Dichlorprop, Dichlorprop-p, Fluazifop, Fluroxypyr, MCPA, Mecoprop and Mecoprop-p) on cereals (rye). The method involves an alkaline hydrolysis with sodium hydroxide in order to release covalently bound compounds, prior to QuEChERS extraction, followed by neutralization and analysis via liquid chromatography-double mass spectrometry LC/MS/MS. The performance of the method either with or without alkaline hydrolysis was studied in terms of recovery rates and limit of quantification (LOQ). In either case, recoveries were determined at four spiking levels (0.02 mg/kg, 0.05 mg/kg, 0.1 mg/kg and 0.5 mg/kg) with 5 replicates for each level. Mean recoveries ranged from 90 to 120 %, whereas relative standard deviations (RSD %) proved to be less than 20 %. Quantitative analysis was carried out by the internal standard (Nicarbazin) and the LC/MS/MS analysis was performed in electrospray ionisation (ESI) negative mode using a Zorbax XCB Eclipse column. The developed method was applied to the analysis of several cereals commercially available like as rye flour, oat meal, oat flakes and dehusked oat. Residue levels were found below the limit of quantification (LOQ) of the method. The method has been tested in EU Proficiency Tests for cereals with good results. PMID:21726153

  7. Draft Genome Sequence of MCPA-Degrading Sphingomonas sp. Strain ERG5, Isolated from a Groundwater Aquifer in Denmark

    PubMed Central

    Nielsen, Tue Kjærgaard; Sørensen, Sebastian R.; Hansen, Lars Hestbjerg

    2015-01-01

    Sphingomonas sp. strain ERG5 was isolated from a bacterial community, originating from a groundwater aquifer polluted with low pesticide concentrations. This bacterium degrades 2-methyl-4-chlorophenoxyacetic acid (MCPA) in a wide spectrum of concentrations and has been shown to function in bioaugmented sand filters. Genes associated with MCPA degradation are situated on a putative conjugative plasmid. PMID:25676756

  8. Fast determination of phenoxy acid herbicides in carrots and apples using liquid chromatography coupled triple quadrupole mass spectrometry.

    PubMed

    Santilio, Angela; Stefanelli, Patrizia; Dommarco, Roberto

    2009-08-01

    A fast, simple and inexpensive method has been developed for the analysis of phenoxy acid herbicides: 2,4-dichlorophenoxyacetic acid (2,4-D), 4-chloro-2-methylphenoxyacetic acid (MCPA), 2-(4-chloro-o-tolyloxy)propionic acid (MCPP), 2-(4-aryloxyphenoxy)propionic acid (Fluazifop) and 2-(4-aryloxyphenoxy)propionic acid (Haloxyfop) in carrots and apples by liquid chromatography coupled to triple quadrupole mass spectrometry (LC/MS/MS). The compounds were analyzed by QuEChERS (quick, easy, cheap, effective, rugged, safe) methodology without cleanup. The recoveries were performed at two spiked levels (0.05 and 0.5 mg/kg) for both matrices with six replicates for each level. The mean recoveries ranged from 70-92% for both apples and carrots. The precision of the method expressed as relative standard deviation (RSD%) was found to be in the range 3-15%. For all compounds, good linearity (r(2) > 0.99) was obtained over the range of concentration from 0.05 micro g/mL to 0.5 micro g/mL, corresponding to the pesticide concentrations of 0.05 mg/kg and 0.5 mg/kg, respectively. The determination limits (LOQs) ranged from 0.01 ng/mL to 1.3 ng/mL in solvent, whereas, the LOQs calculated in matrix ranged from 0.05 ng/g to 21.0 ng/g for apples and from 0.06 ng/g to 10.2 ng/g for carrots. The developed methodology combines the advantages of both QuEChERS and LC/MS/MS producing a very rapid, sensitive and cheap method useful for the routine analytical laboratories. PMID:20183066

  9. Highly efficient microextraction of chlorophenoxy acid herbicides in natural waters using a decanoic acid-based nanostructured solvent prior to their quantitation by liquid chromatography-mass spectrometry.

    PubMed

    Moral, Antonia; Caballo, Carmen; Sicilia, María Dolores; Rubio, Soledad

    2012-01-01

    Solvents used in microextraction require high solubilising capability to efficiently extract the target compounds. In this article, nanostructured solvents made up of alkyl carboxylic acids (ACAs) aggregate are proposed for the efficient microextraction of acidic pesticides from natural waters. The target compounds were chlorophenoxy acid herbicides (CPAHs) widely used in agriculture, forestry and gardening (viz. 2,4-D, MCPA, MCPP, 2,4,5-T and MCPB). The supramolecular solvents (SUPRASs) tested were generated from solutions of reverse micelles of octanoic (OcA), decanoic (DeA) and dodecanoic (DoA) acid in THF by the addition of water, which acted as the coacervating agent. The DeA-based SUPRAS was the most efficient extractant for CPAHs; actual concentration factors (ACFs) of 260 for 2,4-D, 290 for MCPA, and 400 for MCPP, 2,4,5-T and MCPB were obtained. The explanation for so high ACFs can be found in the extremely efficient retention mechanisms that the DeA-based SUPRAS provides for CPAHs (i.e. formation of hydrogen bonds and hydrophobic interactions), and the high number of binding sites that it contains (i.e. the concentration of biosurfactant in the SUPRAS was 0.56 mg μL(-1)). Both characteristics permitted to effectively extract the target analytes in a low volume of solvent (about 2 μL of solvent per mL of sample). Others assets of the proposed supramolecular solvent-based microextraction (SUSME) approach included recoveries no dependent on matrix composition, rapidity (sample treatment spent about 15 min), use of low volume of sample (63 mL per analysis) and simplicity (no special lab equipments was needed). Combination with liquid chromatography/ion-trap mass spectrometry [LC-(IT)MS] afforded method quantitation limits for CPAHs within the interval 22-30 ng L(-1). The precision of the method, expressed as relative standard deviation (n=11, [CPAH]=200 ng L(-1)), was in the range 2.9-5.8%. The applicability of the method to the analysis of natural waters

  10. Study of the Effect of UV Radiation on the Decomposition of 4-Chloro-2-Methylphenoxyacetic Acid

    NASA Astrophysics Data System (ADS)

    Tchaikovskaya, O. N.; Karetnikova, E. A.; Sokolova, I. V.; Mayer, G. V.

    2013-12-01

    The influence of UV radiation wavelength on the disappearance kinetics of 4-chloro-2-methylphenoxyacetic acid (MCPA) in the presence of activated sludge and humic acids has been examined. Variations in the kinetic curves of MCPA removal in the presence of humic acids were determined from results on accumulation of carbon dioxide gas. Spectral-luminescence and chromato-mass-spectrometry data reveal the presence in the medium of the biotransformation product 2-methyl-4-chlorophenol, which is utilized after 14 days. Addition of humic acids, on the one hand, reduced the rates of subsequent biodecomposition of MCPA. On the other hand, in the process of transformation of the herbicide in the presence of humic acids a photobioproduct was detected which does not contain chlorine: 2-methylphenoxyacetic acid.

  11. Identification of the mcpA and mcpM Genes, Encoding Methyl-Accepting Proteins Involved in Amino Acid and l-Malate Chemotaxis, and Involvement of McpM-Mediated Chemotaxis in Plant Infection by Ralstonia pseudosolanacearum (Formerly Ralstonia solanacearum Phylotypes I and III)

    PubMed Central

    Hida, Akiko; Oku, Shota; Kawasaki, Takeru; Nakashimada, Yutaka; Tajima, Takahisa

    2015-01-01

    Sequence analysis has revealed the presence of 22 putative methyl-accepting chemotaxis protein (mcp) genes in the Ralstonia pseudosolanacearum GMI1000 genome. PCR analysis and DNA sequencing showed that the highly motile R. pseudosolanacearum strain Ps29 possesses homologs of all 22 R. pseudosolanacearum GMI1000 mcp genes. We constructed a complete collection of single mcp gene deletion mutants of R. pseudosolanacearum Ps29 by unmarked gene deletion. Screening of the mutant collection revealed that R. pseudosolanacearum Ps29 mutants of RSp0507 and RSc0606 homologs were defective in chemotaxis to l-malate and amino acids, respectively. RSp0507 and RSc0606 homologs were designated mcpM and mcpA. While wild-type R. pseudosolanacearum strain Ps29 displayed attraction to 16 amino acids, the mcpA mutant showed no response to 12 of these amino acids and decreased responses to 4 amino acids. We constructed mcpA and mcpM deletion mutants of highly virulent R. pseudosolanacearum strain MAFF106611 to investigate the contribution of chemotaxis to l-malate and amino acids to tomato plant infection. Neither single mutant exhibited altered virulence for tomato plants when tested by root dip inoculation assays. In contrast, the mcpM mutant (but not the mcpA mutant) was significantly less infectious than the wild type when tested by a sand soak inoculation assay, which requires bacteria to locate and invade host roots from sand. Thus, McpM-mediated chemotaxis, possibly reflecting chemotaxis to l-malate, facilitates R. pseudosolanacearum motility to tomato roots in sand. PMID:26276117

  12. Potential organic herbicides for squash production: Pelargonic acid herbicides AXXE® and Scythe®

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Organic squash (Cucurbita pepo L.) producers need appropriate herbicides that can effectively provide season-long weed control. Although corn gluten meal has shown promise as an early-season pre-emergent organic herbicide in squash production, any uncontrolled weeds can inflict serious yield reducti...

  13. Potential organic herbicides for squash production: Pelargonic acid herbicides AXXE (registered trademark) and Scythe (registered trademark)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Organic squash (Cucurbita pepo L.) producers need appropriate herbicides that can effectively provide season- long weed control. Research was conducted in southeast Oklahoma (Atoka County, Lane, OK) to determine the impact of potential organic herbicides on weed control efficacy, crop injury, and y...

  14. Calibration of a passive sampling device for time-integrated sampling of hydrophilic herbicides in aquatic environments.

    PubMed

    Tran, Anh T K; Hyne, Ross V; Doble, P

    2007-03-01

    Two types of solid-phase materials, a styrenedivinylbenzene copolymer sorbent (embedded in a SDB-XC Empore disk) and a styrenedivinylbenzene copolymer sorbent modified with sulfonic acid functional groups (embedded in a SDB-RPS Empore disk), were compared as a receiving phase in a passive sampling device for monitoring polar pesticides. The SDB-XC Empore disk was selected for further evaluation, overlayed with either a polysulfone or a polyethersulfone diffusion membrane. The target herbicides included five nonionized herbicides (simazine, atrazine, diuron, clomazone, and metolachlor) and four phenoxy acid herbicides (dicamba, (2,4-dichlorophenoxy)acetic acid [2,4-D], (4-chloro-2-methylphenoxy)acetic acid [MCPA], and triclopyr) with log octanol/water partition coefficient (log K(OW)) values of less than three in water. Uptake of these herbicides generally was higher into a device constructed of a SDB-XC Empore disk as a receiving phase covered with a polyethersulfone membrane compared to a similar device covered with a polysulfone membrane. Using the device with a SDB-XC Empore disk covered with a polyethersulfone membrane, linear uptake of simazine, atrazine, diuron, clomazone, and metolachlor was observed for up to 21 d, and daily sampling rates of the herbicides from water in a laboratory flow-through system were determined. The uptake rate of each nonionized herbicide by the Empore disk-based passive sampler was linearly proportional to its concentration in the water, and the sampling rate was independent of the water concentrations over the 21-d period. Uptake of the phenoxy acid herbicides (2,4-D, MCPA, and triclopyr) obeyed first-order kinetics and rapidly reached equilibrium in the passive sampler after approximately 12 d of exposure. The Empore disk-based passive sampler displayed isotropic kinetics, with a release half-life for triclopyr of approximately 6 d. PMID:17373506

  15. Pelargonic acid as a post-directed herbicide for onions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Organic onion producers need appropriate herbicides that can effectively provide post-emergent weed control. Research was conducted in southeast Oklahoma (Atoka County, Lane, OK) to determine the impact of a potential organic herbicide on weed control efficacy, crop injury, and yields. The experim...

  16. Acidic herbicides in surface waters of Lower Fraser Valley, British Columbia, Canada.

    PubMed

    Woudneh, Million B; Sekela, Mark; Tuominen, Taina; Gledhill, Melissa

    2007-01-12

    In the period 2003-2005 a study was conducted to determine the occurrence, spatial and temporal distribution of five acidic herbicides in the Lower Fraser Valley (LFV) region of British Columbia, Canada. A high-resolution gas chromatography/high-resolution mass spectrometry (HRGC/HRMS) method capable of detecting analytes at the sub ng/L level was developed for this study. Samples were collected and analyzed from two references, five agricultural, two urban and five agricultural and urban mixed sites. Only (4-chloro-2-methylphenoxy)acetic acid and triclopyr were detected at the reference sites. The highest concentration of herbicide detected at the reference sites was 0.109ng/L for (4-chloro-2-methylphenoxy)acetic acid. Varying levels of all of the herbicides monitored were detected at the urban, agricultural and the mixed sites. For the urban sites the highest concentration of herbicide detected was 66.6ng/L for 2-(4-chloro-2-methylphenoxy)propanoic acid. For the agricultural sites the highest concentration of herbicide detected was 345ng/L for (2,4-dichlorophenoxy)acetic acid (2,4-D). For the mixed sites the highest concentration of herbicide detected was 1230ng/L for 2,4-D. Overall the mixed sites showed highest concentrations and detection frequencies followed by the agricultural and urban sites. With few exceptions higher concentrations of herbicides were observed for samples collected during spring than for samples collected during fall. The detected concentrations of herbicides were evaluated against established water quality criteria. Herbicide data presented in this study provide reference levels for future pesticide monitoring programs in the region. PMID:17118381

  17. Determination and occurrence of phenoxyacetic acid herbicides and their transformation products in groundwater using ultra high performance liquid chromatography coupled to tandem mass spectrometry.

    PubMed

    McManus, Sarah-Louise; Moloney, Mary; Richards, Karl G; Coxon, Catherine E; Danaher, Martin

    2014-01-01

    A sensitive method was developed and validated for ten phenoxyacetic acid herbicides, six of their main transformation products (TPs) and two benzonitrile TPs in groundwater. The parent compounds mecoprop, mecoprop-p, 2,4-D, dicamba, MCPA, triclopyr, fluroxypr, bromoxynil, bentazone, and 2,3,6-trichlorobenzoic acid (TBA) are included and a selection of their main TPs: phenoxyacetic acid (PAC), 2,4,5-trichloro-phenol (TCP), 4-chloro-2-methylphenol (4C2MP), 2,4-dichlorophenol (DCP), 3,5,6-trichloro-2-pyridinol (T2P), and 3,5-dibromo-4-hydroxybenzoic acid (BrAC), as well as the dichlobenil TPs 2,6-dichlorobenzamide (BAM) and 3,5-dichlorobenzoic acid (DBA) which have never before been determined in Irish groundwater. Water samples were analysed using an efficient ultra-high performance liquid chromatography (UHPLC) method in an 11.9 min separation time prior to detection by tandem mass spectrometry (MS/MS). The limit of detection (LOD) of the method ranged between 0.00008 and 0.0047 µg·L(-1) for the 18 analytes. All compounds could be detected below the permitted limits of 0.1 µg·L(-1) allowed in the European Union (EU) drinking water legislation. The method was validated according to EU protocols laid out in SANCO/10232/2006 with recoveries ranging between 71% and 118% at the spiked concentration level of 0.06 µg·L(-1). The method was successfully applied to 42 groundwater samples collected across several locations in Ireland in March 2012 to reveal that the TPs PAC and 4C2MP were detected just as often as their parent active ingredients (a.i.) in groundwater. PMID:25514054

  18. Nuclear Magnetic Resonance Identification of New Sulfonic Acid Metabolites of Chloroacetanilide Herbicides

    USGS Publications Warehouse

    Morton, M.D.; Walters, F.H.; Aga, D.S.; Thurman, E.M.; Larive, C.K.

    1997-01-01

    The detection of the sulfonic acid metabolites of the chloroacetanilide herbicides acetochlor, alachlor, butachlor, propachlor, and, more recently, metolachlor in surface and ground water suggests that a common mechanism for dechlorination exists via the glutathione conjugation pathway. The identification of these herbicides and their metabolites is important due to growing public awareness and concern about pesticide levels in drinking water. Although these herbicides are regulated, little is known about the fate of their metabolites in soil. The sulfonic acid metabolites were synthesized by reaction of the parent compounds with an excess of sodium sulfite. Acetochlor, alachlor, butachlor, metolachlor, and propachlor and their sulfonic acid metabolites were studied by nuclear magnetic resonance spectroscopy and fast atom bombardment mass spectrometry. This paper provides a direct method for the preparation and characterization of these compounds that will be useful in the analysis and study of chloracetanilide herbicides and their metabolites.

  19. Controlled Release Formulations of Auxinic Herbicides

    NASA Astrophysics Data System (ADS)

    Kowalski, Witold J.; Siłowiecki, Andrzej.; Romanowska, Iwona; Glazek, Mariola; Bajor, Justyna; Cieciwa, Katarzyna; Rychter, Piotr

    2013-04-01

    Controlled release formulations are applied extensively for the release of active ingredients such as plant protection agents and fertilizers in response to growing concern for ecological problems associated with increased use of plant protection chemicals required for intensive agricultural practices [1]. We synthesized oligomeric mixtures of (R,S)-3-hydroxy butyric acid chemically bonded with 2,4-D, Dicamba and MCPA herbicides (HBA) respectively, and determined their molecular structure and molecular weight dispersion by the size exclusion chromatography, proton magnetic resonance spectrometry and electro-spray ionization mass spectrometry. Further we carried out bioassays of herbicidal effectiveness of the HBA herbicides vs. series of dicotyledonous weeds and crop injury tests [2, 3, 4]. Field bioassays were accomplished according to the EPPO standards [5]. Groups of representative weeds (the development stages in the BCCH scale: 10 - 30) were selected as targets. Statistical variabilities were assessed by the Fisher LSD test for plants treated with the studied herbicides in form of HBA oligomers, the reference herbicides in form of dimethyl ammonium salts (DMA), and untreated plants. No statistically significant differences in the crop injuries caused by the HBA vs. the DMA reference formulation were observed. The effectiveness of the HBA herbicides was lower through the initial period (ca. 2 weeks) relative to the DMA salts, but a significant increase in the effectiveness of the HBA systems followed during the remaining fraction of each assay. After 6 weeks all observed efficiencies approached 100%. The death of weeds treated with the HBA herbicides was delayed when compared with the DMA reference herbicides. The delayed uptake observed for the HBA oligomers relative to the DMA salts was due to controlled release phenomena. In case of the DMA salts the total amount of active ingredients was available at the target site. By contrast, the amount of an active

  20. PERFORMANCE EVALUATION OF PARTICLE BEAM LIQUID CHROMATOGRAPHY/MASS SPECTROMETRY FOR THE MEASUREMENT OF ACID HERBICIDES

    EPA Science Inventory

    Particle beam liquid chromatography/mass spectrometry (LC/MS) was evaluated for the measurement of acid herbicides. n acetic acid/ammonium acetate/methano1 solvent system with a C-8 reversed Phase column gave baseline resolution of all target analytes. etection limits in the full...

  1. Effect of carbonaceous soil amendments on potential mobility of weak acid herbicides in soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Use of carbonaceous amendments in soil has been proposed to decrease potential offsite transport of weak acid herbicides and metabolites by increasing their sorption to soil. The effects of organic olive mill waste, biochars from different feed stocks, and humic acid bound to clay on sorption of MCP...

  2. Fermentation and alternative oxidase contribute to the action of amino acid biosynthesis-inhibiting herbicides.

    PubMed

    Zulet, Amaia; Gil-Monreal, Miriam; Zabalza, Ana; van Dongen, Joost T; Royuela, Mercedes

    2015-03-01

    Acetolactate synthase inhibitors (ALS-inhibitors) and glyphosate (GLP) are two classes of herbicide that act by the specific inhibition of an enzyme in the biosynthetic pathway of branched-chain or aromatic amino acids, respectively. The physiological effects that are detected after application of these two classes of herbicides are not fully understood in relation to the primary biochemical target inhibition, although they have been well documented. Interestingly, the two herbicides' toxicity includes some common physiological effects suggesting that they kill the treated plants by a similar pattern despite targeting different enzymes. The induction of aerobic ethanol fermentation and alternative oxidase (AOX) are two examples of these common effects. The objective of this work was to gain further insight into the role of fermentation and AOX induction in the toxic consequences of ALS-inhibitors and GLP. For this, Arabidopsis T-DNA knockout mutants of alcohol dehydrogenase (ADH) 1 and AOX1a were used. The results found in wild-type indicate that both GLP and ALS-inhibitors reduce ATP production by inducing fermentation and alternative respiration. The main physiological effects in the process of herbicide activity upon treated plants were accumulation of carbohydrates and total free amino acids. The effects of the herbicides on these parameters were less pronounced in mutants compared to wild-type plants. The role of fermentation and AOX regarding pyruvate availability is also discussed. PMID:25544587

  3. Determination of phenoxy acid herbicides in water by electron-capture and microcoulometric gas chromatography

    USGS Publications Warehouse

    Goerlitz, D.F.; Lamar, William L.

    1967-01-01

    A sensitive gas chromatographic method using microcoulometric titration and electron-capture detection for the analysis of 2,4-D, silvex, 2,4,5-T, and other phenoxy acid herbicides in water is described. The herbicides are extracted from unfiltered water samples (800-1,000 ml) by use of ethyl ether ; then the herbicides are concentrated and esterilied. To allow the analyst a choice, two esterilication procedures--using either boron trifluoride-methanol or diazomethane--are evaluated. Microcoulometric gas chromatography is specific for the detection of halogenated compounds such as the phenoxy acid herbicides whereas it does not respond to nonhalogenated components. Microcoulometric gas chromatography requires care and patience. It is not convenient for rapid screening of l-liter samples that contain less than 1 microgram of the herbicide. Although electroncapture gas chromatography is less selective and more critically affected by interfering substances, it is, nevertheless, convenient and more sensitive than microcoulometric gas chromatography. Two different liquid phases are used in the gas chromatographic columns--DC-200 silicone in one column and QF-1 silicone in the other. The performance of both columns is improved by the addition of Carbowax 20M. The Gas Chrom Q support is coated with the liquid phases by the 'frontal-analysis' technique. The practical lower limits for measurement of the phenoxy acid herbicides in water primarily depend upon the sample size, interferences present, anal instrumentation used. With l-liter samples of water, the practical lower limits of measurement are 10 ppt (parts per trillion) for 2,4-D and 2 ppt for silvex and 2,4,5-T when electron-capture detection is used, and approximately 20 ppt for each herbicide when analyzed by microcoulometric-titration gas chromatography. Recoveries of the herbicides immediately after addition to unfiltered water samples averaged 92 percent for 2,4-D, 90 percent for silvex, and 98 percent for 2

  4. DEVELOPMENTS IN THE SUPERCRITICAL FLUID EXTRACTION OF CHLOROPHENOXY ACID HERBICIDES FROM SOIL SAMPLES

    EPA Science Inventory

    Extraction of chlorophenoxy acid herbicides from soil samples with supercritical carbon dioxide as extractant and tetrabutylammonium hydroxide and methyl iodide as derivatization agents was investigated. The extraction was carried out at 400 atm and 80 C for 15 min static, follow...

  5. Determination of commonly used polar herbicides in agricultural drainage waters in Australia by HPLC.

    PubMed

    Tran, Anh T K; Hyne, Ross V; Doble, Philip

    2007-03-01

    The present study describes the application of different extraction techniques for the preconcentration of ten commonly found acidic and non-acidic polar herbicides (2,4-D, atrazine, bensulfuron-methyl, clomazone, dicamba, diuron, MCPA, metolachlor, simazine and triclopyr) in the aqueous environment. Liquid-liquid extraction (LLE) with dichloromethane, solid-phase extraction (SPE) using Oasis HLB cartridges or SBD-XC Empore disks were compared for extraction efficiency of these herbicides in different matrices, especially water samples from contaminated agricultural drainage water containing high concentrations of particulate matter. Herbicides were separated and quantified by high performance liquid chromatography (HPLC) with an ultraviolet detector. SPE using SDB-XC Empore disks was applied to determine target herbicides in the Murrumbidgee Irrigation Area (NSW, Australia) during a two-week survey from October 2005 to November 2005. The daily aqueous concentrations of herbicides from 24-h composite samples detected at two sites increased after run-off from a storm event and were in the range of: 0.1-17.8 microg l(-1), < 0.1-0.9 microg l(-1) and 0.2-17.8 microg l(-1) at site 1; < 0.1-3.5 microg l(-1), < 0.1-0.2 microg l(-1) and < 0.2-3.2 microg l(-1) at site 2 for simazine, atrazine and diuron, respectively. PMID:17184816

  6. Impairment of cellulose- and cellobiose-degrading soil Bacteria by two acidic herbicides.

    PubMed

    Schellenberger, Stefanie; Drake, Harold L; Kolb, Steffen

    2012-02-01

    Herbicides have the potential to impair the metabolism of soil microorganisms. The current study addressed the toxic effect of bentazon and 4-chloro-2-methylphenoxyacetic acid on aerobic and anaerobic Bacteria that are involved in cellulose and cellobiose degradation in an agricultural soil. Aerobic saccharide degradation was reduced at concentrations of herbicides above environmental values. Microbial processes (e.g. fermentations, ferric iron reduction) that were linked to anaerobic cellulose and cellobiose degradation were reduced in the presence of both herbicides at concentrations above and at those that occur in crop field soil. 16S rRNA gene transcript numbers of total Bacteria, and selected bacterial taxa (Clostridia [Group I], Planctomycetaceae, and two uncultivated taxa of Bacteroidetes) decreased more in anoxic than in oxic cellulose-supplemented soil microcosms in the presence of both herbicides. Collectively, the results suggested that the metabolism of anaerobic cellulose-degrading Bacteria was impaired by typical in situ herbicide concentrations, whereas in situ concentrations did not impair metabolism of aerobic cellulose- and cellobiose-degrading soil Bacteria. PMID:22098368

  7. Effects of herbicides on the concentration of poisonous compounds in plants: a review.

    PubMed

    Williams, M C; James, L F

    1983-12-01

    Herbicides may raise, lower, or not affect the concentration of poisonous compounds in plants. Herbicides, 2,4,5-T and silvex controlled Wasatch milkvetch (Astragalus miser var oblongifolius) and markedly reduced the concentration of miserotoxin, a poisonous aliphatic nitro compound. The concentration of phototoxic furocoumarins in the leaves of spring parsley (Cymopterus watsonii) decreased to nontoxic concentrations 4 to 5 weeks after treatment with 2,4-D. The hydrocyanic acid content of wild cherry (Prunus spp) decreased after treatment with 2,4-D and 2,4,5-T, but increased in Sudangrass (Sorghum halapense) after treatment with 2,4-D. The alkaloid concentration in Barbey larkspur (Delphinium barbeyi) increased after treatment with 2,4,5-T or silvex, decreased in horsetail (Equisetum palustre) after treatment with MCPA, and was unaffected in Datura after treatment with several herbicides. The effect of herbicides on nitrate concentration in plants was dependent upon the species of plant and the herbicide used. PMID:6318617

  8. Herbicidal inhibitors of amino acid biosynthesis and herbicide-tolerant crops.

    PubMed

    Tan, S; Evans, R; Singh, B

    2006-03-01

    Acetohydroxyacid synthase (AHAS) inhibitors interfere with branched-chain amino acid biosynthesis by inhibiting AHAS. Glyphosate affects aromatic amino acid biosynthesis by inhibiting 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS). Glufosinate inhibits glutamine synthetase and blocks biosynthesis of glutamine. AHAS gene variants that confer tolerance to AHAS inhibitors have been discovered in plants through selection or mutagenesis. Imidazolinone-tolerant crops have been commercialized based on these AHAS gene variants. A modified maize EPSPS gene and CP4-EPSPS gene from Agrobacterium sp. have been used to transform plants for target-based tolerance to glyphosate. A gox gene isolated from Ochrobactrum anthropi has also been employed to encode glyphosate oxidoreductase to detoxify glyphosate in plants. Glyphosate-tolerant crops with EPSPS transgene alone or both EPSPS and gox transgenes have been commercialized. Similarly, bar and pat genes isolated from Streptomyces hygroscopicus and S. viridochromogenes, respectively, have been inserted into plants to encode phosphinothricin N-acetyltransferase to detoxify glufosinate. Glufosinate-tolerant crops have been commercialized using one of these two transgenes. PMID:16547651

  9. TRACE ANALYSIS OF FLUORESCEIN-DERIVATIZED PHENOXY ACID HERBICIDES BY MICELLAR ELECTROKINETIC CHROMATOGRAPHY WITH LASER-INDUCTED FLUORESCENCE DETECTION

    EPA Science Inventory

    Micellar electrokinetic chromatography (MEKC) with laser-induced fluorescence (LIF) detection was used for the trace analysis of phenoxy acid herbicides. Capillary electrophoresis (CE) with LIF detection, which has not previously been used for pesticide analysis, overcomes the po...

  10. Removal of compounds used as plasticizers and herbicides from water by means of gamma irradiation.

    PubMed

    Rivera-Utrilla, José; Daiem, Mahmoud M Abdel; Sánchez-Polo, Manuel; Ocampo-Pérez, Raúl; López-Peñalver, Jesús J; Velo-Gala, Inmaculada; Mota, Antonio J

    2016-11-01

    Gamma radiation has been used to induce the degradation of compounds used as plasticizers and herbicides such as phthalic acid (PA), bisphenol A (BPA), diphenolic acid (DPA), 2,4-dichlorophenoxy-acetic acid (2,4-D), and 4-chloro-2-methylphenoxyacetic acid (MCPA) in aqueous solution, determining the dose constants, removal percentages, and radiation-chemical yields. The reaction rate constants of hydroxyl radical (HO), hydrated electron (eaq(-)) and hydrogen atom (H) with these pollutants were also obtained by means of competition kinetics, using 3-aminopyridine and atrazine as reference compounds. The results indicated that the elimination of these pollutants with gamma radiation mainly follows the oxidative pathway through reaction with HO radicals. The degradation by-products from the five pollutants were determined, detecting that the hydroxylation of the corresponding parent compounds was the main chemical process in the degradation of the pollutants. Moreover, a high decrease in the chemical oxygen demand has been observed for all pollutants. As expected, the degradation by-products generated by the irradiation of PA, BPA and DPA showed a lower toxicity than the parent compounds, however, in the case of 2,4-D and MCPA irradiation, interestingly, their by-products were more toxic than the corresponding original compounds. PMID:27366982

  11. Does microbial centimeter-scale heterogeneity impact MCPA degradation in and leaching from a loamy agricultural soil?

    PubMed

    Rosenbom, Annette E; Binning, Philip J; Aamand, Jens; Dechesne, Arnaud; Smets, Barth F; Johnsen, Anders R

    2014-02-15

    The potential for pesticide degradation varies greatly at the centimeter-scale in agricultural soil. Three dimensional numerical simulations were conducted to evaluate how such small-scale spatial heterogeneity may affect the leaching of the biodegradable pesticide 2-methyl-4-chlorophenoxyacetic acid (MCPA) in the upper meter of a variably-saturated, loamy soil profile. To incorporate realistic spatial variation in degradation potential, we used data from a site where 420 mineralization curves over 5 depths have been measured. Monod kinetics was fitted to the individual curves to derive initial degrader biomass values, which were incorporated in a reactive transport model to simulate heterogeneous biodegradation. Six scenarios were set up using COMSOL Multiphysics to evaluate the difference between models having different degrader biomass distributions (homogeneous, heterogeneous, or no biomass) and either matrix flow or preferential flow through a soil matrix with a wormhole. MCPA leached, within 250 days, below 1m only when degrader biomass was absent and preferential flow occurred. Both biodegradation in the plow layer and the microbially active lining of the wormhole contributed to reducing MCPA-leaching below 1m. The spatial distribution of initial degrader biomass within each soil matrix layer, however, had little effect on the overall MCPA-leaching. PMID:24291558

  12. Determination of Acid Herbicides Using Modified QuEChERS with Fast Switching ESI(+)/ESI(-) LC-MS/MS.

    PubMed

    Sack, Chris; Vonderbrink, John; Smoker, Michael; Smith, Robert E

    2015-11-01

    A method for the determination of 35 acid herbicides in food matrices was developed, validated, and implemented. It utilizes a modified QuEChERS extraction procedure coupled with quantitation by liquid chromatography tandem mass spectrometry (LC-MS/MS). The acid herbicides analyzed are all organic carboxylic acids, including the older chlorophenoxy acid herbicides such as 2,4-dichlorophenoxyacetic acid (2,4-D), dicamba, 4-chlorophenoxyacetic acid (4-CPA), quinclorac, and many of the newer imidazolinone herbicides such as imazethapyr and imazaquin. In the procedure, 10 mL of water is added to 5 g of sample and then extracted with 1% formic acid in acetonitrile for 1 min. The acetonitrile phase is salted out of the extract by adding sodium chloride and magnesium sulfate, followed by centrifugation. The acetonitrile is diluted 1:1 with water to enable quantitation by LC-MS/MS using fast switching between positive and negative electrospray ionization modes. The average recoveries for all the compounds except aminocyclopyrachlor were 95% with a precision of 8%. The method detection limits for all residues were less than 10 ng/g, and the correlation coefficients for the calibration curves was greater than 0.99 for all but two compounds tested. The method was used successfully for the quantitation of acid herbicides in the FDA's total diet study. The procedure proved to be accurate, precise, linear, sensitive, and rugged. PMID:26473587

  13. Occurrence and fate of the herbicide glyphosate and its degradate aminomethylphosphonic acid in the atmosphere.

    PubMed

    Chang, Feng-chih; Simcik, Matt F; Capel, Paul D

    2011-03-01

    This is the first report on the ambient levels of glyphosate, the most widely used herbicide in the United States, and its major degradation product, aminomethylphosphonic acid (AMPA), in air and rain. Concurrent, weekly integrated air particle and rain samples were collected during two growing seasons in agricultural areas in Mississippi and Iowa. Rain was also collected in Indiana in a preliminary phase of the study. The frequency of glyphosate detection ranged from 60 to 100% in both air and rain. The concentrations of glyphosate ranged from <0.01 to 9.1 ng/m(3) and from <0.1 to 2.5 µg/L in air and rain samples, respectively. The frequency of detection and median and maximum concentrations of glyphosate in air were similar or greater to those of the other high-use herbicides observed in the Mississippi River basin, whereas its concentration in rain was greater than the other herbicides. It is not known what percentage of the applied glyphosate is introduced into the air, but it was estimated that up to 0.7% of application is removed from the air in rainfall. Glyphosate is efficiently removed from the air; it is estimated that an average of 97% of the glyphosate in the air is removed by a weekly rainfall ≥ 30 mm. PMID:21128261

  14. Occurrence and fate of the herbicide glyphosate and its degradate aminomethylphosphonic acid in the atmosphere

    USGS Publications Warehouse

    Chang, Feng-Chih; Simcik, M.F.; Capel, P.D.

    2011-01-01

    This is the first report on the ambient levels of glyphosate, the most widely used herbicide in the United States, and its major degradation product, aminomethylphosphonic acid (AMPA), in air and rain. Concurrent, weekly integrated air particle and rain samples were collected during two growing seasons in agricultural areas in Mississippi and Iowa. Rain was also collected in Indiana in a preliminary phase of the study. The frequency of glyphosate detection ranged from 60 to 100% in both air and rain. The concentrations of glyphosate ranged from 3 and from <0.1 to 2.5 µg/L in air and rain samples, respectively. The frequency of detection and median and maximum concentrations of glyphosate in air were similar or greater to those of the other high-use herbicides observed in the Mississippi River basin, whereas its concentration in rain was greater than the other herbicides. It is not known what percentage of the applied glyphosate is introduced into the air, but it was estimated that up to 0.7% of application is removed from the air in rainfall. Glyphosate is efficiently removed from the air; it is estimated that an average of 97% of the glyphosate in the air is removed by a weekly rainfall ≥30 mm.

  15. Comparison of two screening bioassays, based on the frog sciatic nerve and yeast cells, for the assessment of herbicide toxicity.

    PubMed

    Papaefthimiou, Chrisovalantis; Cabral, Maria de Guadalupe; Mixailidou, Christina; Viegas, Cristina A; Sá-Correia, Isabel; Theophilidis, George

    2004-05-01

    Two different test systems, one based on the isolated sciatic nerve of an amphibian and the other on a microbial eukaryote, were used for the assessment of herbicide toxicity. More specifically, we determined the deleterious effects of increasing concentrations of herbicides of different chemical classes (phenoxyacetic acids, triazines, and acetamides), and of 2,4-dichlorophenol (2,4-DCP), a degradation product of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D), on electrophysiological parameters and the vitality of the axons of the isolated sciatic nerve of the frog (Rana ridibunda) and on the growth curve of the yeast Saccharomyces cerevisiae based on microtiter plate susceptibility assays. The no-observed-effect-concentration (NOEC), defined as the maximum concentration of the tested compound that has no effect on these biological parameters, was estimated. In spite of the different methodological approaches and biological systems compared, the NOEC values were identical and correlated with the lipophilicity of the tested compounds. The relative toxicity established here, 2,4-DCP > alachlor, metolachlor > metribuzin > 2,4-D, 2-methyl-4-chlorophenoxyacetic acid (MCPA), correlates with the toxicity indexes reported in the literature for freshwater organisms. Based on these results, we suggest that the relatively simple, rapid, and low-cost test systems examined here may be of interest as alternative or complementary tests for toxicological assessment of herbicides. PMID:15180372

  16. BOREAS TGB-7 Dry Deposition Herbicide and Organochlorine Flux Data

    NASA Technical Reports Server (NTRS)

    Waite, Don; Conrad, Sara K. (Editor); Hall, Forrest G. (Editor)

    2000-01-01

    The BOREAS TGB-7 team measured the concentration and flux of several agricultural pesticides in air, rainwater, and dry deposition samples in order to determine the associated yearly deposition rates. This data set contains information on the dry deposition flux of seven herbicides [2,4- dichlorophenoxyacidic_acid (2,4-D), bromoxynil, dicamb, 2-methyl-4-chlorophenoxyacetic acid (MCPA), triallate, trifluralin, and diclop-methyl] known to appear in the atmosphere of the Canadian prairies. Also, the concentration of three herbicides (atrazine, alachlor, and metolachlor), two groups of insecticides (lindane and breakdown products and dichloro-diphenyl-trichloroethane (DDT) and breakdown products), and several polychlorinated biphenyls commonly used in the central United States was measured. All of these chemicals are reported, in the literature, to be transported in the atmosphere. Many have been reported to occur in boreal and arctic food chains. The sampling was carried out from 16-Jun to 13-Aug-1993 and 04-May to 20-Jul-1994 at the BOREAS site in the Prince Albert National Park (Waskesiu). The data are stored in tabular ASCII files.

  17. BOREAS TGB-7 Ambient Air Herbicide and Organochlorine Concentration Data

    NASA Technical Reports Server (NTRS)

    Waite, Don; Hall, Forrest G. (Editor); Conrad, Sara K. (Editor)

    2000-01-01

    The BOReal Ecosystem-Atmosphere Study Trace Gas Biogeochemistry (BOREAS TGB)-7 team measured the concentration and flux of several agricultural pesticides in air, rainwater, and dry deposition samples in order to determine the associated yearly deposition rates. This data set contains information on the ambient air concentration of seven herbicides [2,4- dichlorophenoxyacidic_acid (2,4-D), bromoxynil, dicamb, 2-methyl-4-chlorophenoxyacetic acid (MCPA), triallate, trifluralin, and diclop-methyl] known to appear in the atmosphere of the Canadian prairies. Also, the concentration of three herbicides (atrazine, alachlor, and metolachlor), two groups of insecticides (lindane and breakdown products and dichloro-diphenyl-trichloroethane (DDT) and breakdown products), and several polychlorinated biphenyls commonly used in the central United States was measured. All of these chemicals are reported, in the literature, to be transported in the atmosphere. Many have been reported to occur in boreal and arctic food chains. The sampling was carried out from 16-Jun to 13-Aug-1993 and 04-May to 20-Jul-1994 at the BOREAS site in the Prince Albert National Park (Waskesiu). The data are stored in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884).

  18. BOREAS TGB-7 Rainwater Herbicide and Organochlorine Concentration Data

    NASA Technical Reports Server (NTRS)

    Waite, Don; Conrad, Sara K. (Editor); Hall, Forrest G. (Editor)

    2000-01-01

    The BOREAS TGB-7 team measured the concentration and flux of several agricultural pesticides in air and rainwater samples in order to determine the associated yearly deposition rates. This data set contains information on the rainwater concentration of seven herbicides [2,4- dichlorophenoxyacidic_acid (2,4-D), bromoxynil, dicamb, 2-methyl-4-chlorophenoxyacetic acid (MCPA), triallate, trifluralin, and diclop-methyl] known to appear in the atmosphere of the Canadian prairies. Also, the concentration of three herbicides (atrazine, alachlor, and metolachlor), two groups of insecticides (lindane and breakdown products and dichloro-diphenyl-trichloroethane (DDT) and breakdown products), and several polychlorinated biphenyls commonly used in the central United States was measured. All of these chemicals are reported, in the literature, to be transported in the atmosphere. Many have been reported to occur in boreal and arctic food chains. The sampling was carried out from 16-Jun to 13-Aug-1993 and 04-May to 20-Jul-1994 at the BOREAS site in the Prince Albert National Park (Waskesiu). The data are stored in tabular ASCII files.

  19. Optimization of the polar organic chemical integrative sampler for the sampling of acidic and polar herbicides.

    PubMed

    Fauvelle, Vincent; Mazzella, Nicolas; Belles, Angel; Moreira, Aurélie; Allan, Ian J; Budzinski, Hélène

    2014-05-01

    This paper presents an optimization of the pharmaceutical Polar Organic Chemical Integrative Sampler (POCIS-200) under controlled laboratory conditions for the sampling of acidic (2,4-dichlorophenoxyacetic acid (2,4-D), acetochlor ethanesulfonic acid (ESA), acetochlor oxanilic acid, bentazon, dicamba, mesotrione, and metsulfuron) and polar (atrazine, diuron, and desisopropylatrazine) herbicides in water. Indeed, the conventional configuration of the POCIS-200 (46 cm(2) exposure window, 200 mg of Oasis® hydrophilic lipophilic balance (HLB) receiving phase) is not appropriate for the sampling of very polar and acidic compounds because they rapidly reach a thermodynamic equilibrium with the Oasis HLB receiving phase. Thus, we investigated several ways to extend the initial linear accumulation. On the one hand, increasing the mass of sorbent to 600 mg resulted in sampling rates (R s s) twice as high as those observed with 200 mg (e.g., 287 vs. 157 mL day(-1) for acetochlor ESA). Although detection limits could thereby be reduced, most acidic analytes followed a biphasic uptake, proscribing the use of the conventional first-order model and preventing us from estimating time-weighted average concentrations. On the other hand, reducing the exposure window (3.1 vs. 46 cm(2)) allowed linear accumulations of all analytes over 35 days, but R s s were dramatically reduced (e.g., 157 vs. 11 mL day(-1) for acetochlor ESA). Otherwise, the observation of biphasic releases of performance reference compounds (PRC), though mirroring acidic herbicide biphasic uptake, might complicate the implementation of the PRC approach to correct for environmental exposure conditions. PMID:24691721

  20. MCPA (4-Chloro-2-ethylphenoxyacetate) resistance in hemp-nettle (Galeopsis tetrahit L.).

    PubMed

    Weinberg, Tsafrir; Stephenson, Gerald R; McLean, Michael D; Hall, J Christopher

    2006-11-29

    The physiological basis for MCPA resistance in a hemp-nettle (Galeopsis tetrahit L.) biotype, obtained from a MCPA-resistant field population, was investigated. Dose-response studies revealed that the resistance factor for MCPA, based on GR50 comparisons of total dry weight of resistant (R) and susceptible (S) plants, was 3.3. Resistance factors for fluroxypyr, dicamba, 2,4-D, glyphosate, and chlorsulfuron were 8.2, 1.7, 1.6, 0.7, and 0.6, respectively. MCPA resistance was not due to differences in absorption, because both R and S biotypes absorbed 54% of applied [14C]MCPA 72 h after treatment. However, R plants exported less (45 vs 58% S) recovered 14C out of treated leaves to the apical meristem (6 vs 13% S) and root (32 vs 38% S). In both biotypes, approximately 20% of the 14C recovered in planta was detected as MCPA metabolites. However, less of the 14C recovered in the roots of R plants was MCPA. Therefore, two different mechanisms protect R hemp-nettle from MCPA phytotoxicity: a lower rate of MCPA translocation and a higher rate of MCPA metabolism in the roots. In support of these results, genetic studies indicated that the inheritance of MCPA resistance is governed by at least two nuclear genes with additive effects. PMID:17117800

  1. [Effects of solution pH and simulated acid rain on the behavior of two sulfonylurea herbicides in soil].

    PubMed

    Zhang, Wei; Wang, Jin-Jun

    2007-03-01

    By the methods of batch equilibration and leaching, this paper studied the effects of solution pH and simulated acid rain on the behavior of bensulfuron-methyl and metsulfuron-methyl in soil. The results showed that the adsorption isotherms of these two herbicides fitted Freundlich equation well, and their adsorbed amounts reduced obviously with the increasing pH of water-soil system, which in turn promoted the translocation of the herbicides in soil. The adsorption coefficient (Kf) was positively correlated with soil organic matter and clay contents, while negatively correlated with soil pH. The higher pH of simulated acid rain had a greater contribution on the leaching of the two sulfonylurea herbicides, and their leached amount was increased with increasing acid rain. There was a close relationship between the leaching of the herbicides and the properties of soil. The soils with higher contents of organic matter and clay had a greater retention capability to the herbicides. PMID:17552202

  2. Effect of 2,4-Dichlorophenoxyacetic acid herbicide Escherichia coli growth, chemical, composition, and cellular envelope

    USGS Publications Warehouse

    Carr, R.S.; Biedenbach, J.M.; Hooten, R.L.

    2001-01-01

    2,4-Dichlorophenoxyacetic acid (2,4-D) is a herbicide widely used in the world and mainly excreted by the renal route in exposed humans and animals. Herbicides can affect other nontarget organisms, such as Escherichia coli. We observed that a single exposure to 1 mM 2,4-D diminished growth and total protein content in all E. coli strains tested in vitro. In addition, successive exposures to 0.01 mM 2,4-D had a toxic effect decreasing growth up to early stationary phase. Uropathogenic E. coli adhere to epithelial cells mediated by fimbriae, adhesins, and hydrophobic properties. 2,4-D exposure of uropathogenic E. coli demonstrated altered hydrophobicity and fimbriation. Hydrophobicity index values obtained by partition in p-xylene/water were 300-420% higher in exposed cells than in control ones. Furthermore, values of hemagglutination titer, protein contents in fimbrial crude extract, and electron microscopy demonstrated a significant diminution of fimbriation in treated cells. Other envelope alterations could be detected, such as lipoperoxidation, evidenced by decreased polyunsaturated fatty acids and increased lipid degradation products (malonaldehyde), and motility diminution. These alterations decreased cell adherence to erythrocytes, indicating a diminished pathogenic capacity of the 2,4-D-exposed E. coli. ?? 2001 by John Wiley & Sons, Inc.

  3. Herbicide Transformation

    PubMed Central

    Lanzilotta, R. P.; Pramer, David

    1970-01-01

    A strain of Fusarium solani isolated from soil by enrichment techniques used propanil (3′, 4′-dichloropropionanilide) as a sole source of organic carbon and energy for growth in pure culture. The primary product of the transformation of propanil by F. solani was isolated and identified as 3,4-dichloroaniline (DCA). This compound accumulated in the medium to a level (80 μg/ml) which stopped further herbicide utilization. Herbicide utilization by F. solani was influenced by various environmental and nutritional factors. It was more sensitive to acid than alkaline pH. Added glucose and yeast extract increased the rate of propanil decomposition, and the reduced aeration retarded growth of the fungus and herbicide utilization. The growth of F. solani on propionate was inhibited by added DCA. Images PMID:5437305

  4. DETERMINATION OF CHLORINATED ACID HERBICIDES AND RELATED COMPOUNDS IN WATER BY CAPILLARY ELECTROPHORESIS-ELECTROSPRAY NEGATIVE ION MASS SPECTROMETRY

    EPA Science Inventory

    Capillary electrophoresis electrospray negative ion mass spectrometry was investigated for the determination of chlorinated acid herbicides and several phenols in water. Sixteen analytes were separated as their anions in less than 40 min with a buffer consisting of 5 mM ammonium ...

  5. Degradation of the herbicide 2, 4-dichlorophenoxyacetic acid (2,4-D) dimethylamine salt by gamma radiation from cobalt-60 in aqueous solution containing humic acid

    NASA Astrophysics Data System (ADS)

    Campos, Sandro X.; Vieira, Eny M.; Cordeiro, Paulo J. M.; Rodrigues-Fo, Edson; Murgu, Michael

    2003-12-01

    In this study, gamma radiation from cobalt-60 was used to degrade the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) dimethylamine salt in water in the presence of humic acid. The 2,4-D dimethylamine salt 1.13×10 -4 mol dm -3 solution was irradiated with different doses. HPLC was used as an analytical technique to determine the degradation rate of herbicide studied. The results showed that the herbicide was completely degraded at an absorbed dose of 3 kGy. Degradation decreased when humic acid was added to all the doses. ESI/MS and MS/MS were used to identify the radiolytic degradation products. A fragmentation path for production of 4.6-dichlororesorcinol, is suggested. The radiolytic yields ( G) were calculated.

  6. Determination of herbicides paraquat, glyphosate, and aminomethylphosphonic acid in marijuana samples by capillary electrophoresis.

    PubMed

    Lanaro, Rafael; Costa, José L; Cazenave, Silvia O S; Zanolli-Filho, Luiz A; Tavares, Marina F M; Chasin, Alice A M

    2015-01-01

    In this work, two methods were developed to determine herbicides paraquat, glyphosate, and aminomethylphosphonic acid (AMPA) in marijuana samples by capillary electrophoresis. For paraquat analysis, sample was extracted with aqueous acetic acid solution and analyzed by capillary zone electrophoresis with direct UV detection. The running electrolyte was 50 mmol/L phosphate buffer (pH 2.50). For glyphosate and AMPA, indirect UV/VIS detection was used, as these substances do not present chromophoric groups. Samples were extracted with 5 mmol/L hydrochloric acid. The running electrolyte was 10 mmol/L gallic acid, 6 mmol/L TRIS, and 0.1 mmol/L CTAB (pH = 4.7). The methods presented good linearity, precision, accuracy, and recovery. Paraquat was detected in 12 samples (n = 130), ranging from 0.01 to 25.1 mg/g. Three samples were positive for glyphosate (0.15-0.75 mg/g), and one sample presented AMPA as well. Experimental studies are suggested to evaluate the risks of these concentrations to marijuana user. PMID:25413634

  7. Gas chromatographic and mass spectrometric determination of chlorophenoxy acids and related herbicides as their (cyanoethyl)dimethylsilyl derivatives

    SciTech Connect

    Bertrand, M.J.; Ahmed, A.W.; Sarrasin, B.; Mallet, V.N.

    1987-05-01

    A method for using (2-cyanoethyl)dimethyl(diethylamino)silane to form derivatives with phenoxy acid herbicides and related compounds is presented. Results obtained with 18 compounds demonstrate that the reaction is quantitative and complete within minutes at room temperature. The derivatives formed can readily be analyzed by gas chromatography using a selective nitrogen-phosphorus detector which eliminates the need for rigorous cleanup of the sample required for detection by electron capture. Response-concentration plots show that detection is linear over several decades with limits of detection being in the low picogram range for all compounds studied. Mass spectral analysis of the derivatives of the 18 compounds studied indicates that the spectra are highly specific showing characteristic ions at (M-54), (M-82), and or (M-98) which are useful for structure confirmation or analysis at low levels by using selected ion monitoring. The analytical advantages of the approach for the analysis of acid herbicides are discussed.

  8. Estimation of the validation parameters for a fast analysis of herbicide residues by LC-MS/MS.

    PubMed

    Santilio, A; Girolimetti, S; Barbini, D Attard

    2014-01-01

    Due to strict regulatory requirements for pesticide residue analysis, only the results of residue analysis with acceptable quality should be reported. As a consequence proper validation of the measurement method is required. In this context, accuracy, precision, specificity, limit of determination (LOQ), matrix effect, linearity, uncertainty calculation and ruggedness become increasingly important. This paper reports a description of the validation parameters of a fast method for the determination of five phenoxy acid herbicides (2,4-D, MCPA, MCPP, haloxyfop and fluazifop) in food crops. The recoveries were performed in the concentration range from 0.05 to 0.5 mg kg⁻¹ for apples, pears, carrots and celeriac with five replicates at each level. The mean recoveries ranged from 70% to 95% for all crops. The precision of the method expressed as a relative standard deviation (RSD%) was found to be in the range 3-14%. For all herbicides, the linearity response of the detector was tested by correlation coefficients (r² > 0.99) in the concentration range from 0.05 to 0.5 mg kg⁻¹. The LOQ was determined as the lowest spiked level meeting the requirement of accuracy (70-120%) and precision (RSD% < 20% according to European Union guidelines. The uncertainty and robustness were calculated. On the basis of the results, the method can be considered fast, simple and robust and is suitable to be applied to the analysis of studied herbicides in routine testing laboratories. PMID:24499026

  9. Microbial degradation of herbicides.

    PubMed

    Singh, Baljinder; Singh, Kashmir

    2016-03-01

    Herbicides remain the most effective, efficient and economical way to control weeds; and its market continues to grow even with the plethora of generic products. With the development of herbicide-tolerant crops, use of herbicides is increasing around the world that has resulted in severe contamination of the environment. The strategies are now being developed to clean these substances in an economical and eco-friendly manner. In this review, an attempt has been made to pool all the available literature on the biodegradation of key herbicides, clodinafop propargyl, 2,4-dichlorophenoxyacetic acid, atrazine, metolachlor, diuron, glyphosate, imazapyr, pendimethalin and paraquat under the following objectives: (1) to highlight the general characteristic and mode of action, (2) to enlist toxicity in animals, (3) to pool microorganisms capable of degrading herbicides, (4) to discuss the assessment of herbicides degradation by efficient microbes, (5) to highlight biodegradation pathways, (6) to discuss the molecular basis of degradation, (7) to enlist the products of herbicides under degradation process, (8) to highlight the factors effecting biodegradation of herbicides and (9) to discuss the future aspects of herbicides degradation. This review may be useful in developing safer and economic microbiological methods for cleanup of soil and water contaminated with such compounds. PMID:25159042

  10. Solanum lycopersicum IAA15 functions in the 2,4-dichlorophenoxyacetic acid herbicide mechanism of action by mediating abscisic acid signalling.

    PubMed

    Xu, Tao; Wang, Yanling; Liu, Xin; Gao, Song; Qi, Mingfang; Li, Tianlai

    2015-07-01

    2,4-Dichlorophenoxyacetic acid (2,4-D), an important plant growth regulator, is the herbicide most commonly used worldwide to control weeds. However, broad-leaf fruits and vegetables are extremely sensitive to herbicides, which can cause damage and result in lost crops when applied in a manner inconsistent with the directions. Despite detailed knowledge of the mechanism of 2,4-D, the regulation of auxin signalling is still unclear. For example, although the major mediators of auxin signalling, including auxin/indole acetic acid (AUX/IAA) proteins and auxin response factors (ARFs), are known to mediate auxinic herbicides, the underlying mechanisms are still unclear. In this study, the effects of 2,4-D on AUX/IAA gene expression in tomato were investigated, and the two most notably up-regulated genes, SlIAA15 and SlIAA29, were selected for further study. Western blotting revealed the substantial accumulation of both SlIAA15 and SlIAA29, and the expression levels of the corresponding genes were increased following abscisic acid (ABA) and ethylene treatment. Overexpressing SlIAA15, but not SlIAA29, induced a 2,4-D herbicide damage phenotype. The 35S::SlIAA15 line exhibited a strong reduction in leaf stomatal density and altered expression of some R2R3 MYB genes that are putatively involved in the regulation of stomatal differentiation. Further study revealed that root elongation in 35S::SlIAA15 was sensitive to ABA treatment, and was most probably due to the altered expression of an ABA signal transduction gene. In addition, the altered auxin sensitivities of SlIAA15 transformants were also explored. These results suggested that SlIAA15 plays an important role in determining the effects of the herbicide 2,4-D. PMID:25948703

  11. A mechanistic study of the photodegradation of herbicide 2,4,5-trichlorophenoxyacetic acid in aqueous solution.

    PubMed

    Yurkova, Maria P; Pozdnyakov, Ivan P; Plyusnin, Victor F; Grivin, Vycheslav P; Bazhin, Nikolay M; Kruppa, Alexandr I; Maksimova, Tatiana A

    2013-04-01

    Photodegradation of herbicide 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) in aqueous solution was investigated by stationary (254 nm) and nanosecond laser (266 nm) flash photolysis techniques. It was shown that in the primary photochemical step both photoionization (which generates a hydrated electron-radical cation pair) and heterolytic cleavage of a C-Cl bond takes place. The major products of substitution of one of the chlorine atoms in the 2-, 4- or 5-position by a hydroxyl group as well as the products of hydroxylation of the benzene ring in 3- and 6-positions were identified by HPLC and LC-MS methods. The complexation of 2,4,5-T with β- and γ-cyclodextrins (β(γ)CD) was investigated. The influence of such complexation on the quantum yield of herbicide photolysis and on the ratio of photodegradation products was determined. PMID:23085749

  12. Analysis and detection of the herbicides dimethenamid and flufenacet and their sulfonic and oxanilic acid degradates in natural water

    USGS Publications Warehouse

    Zimmerman, L.R.; Schneider, R.J.; Thurman, E.M.

    2002-01-01

    Dimethenamid [2-chloro-N-(2,4-dimethyl-3-thienyl)-N-(2-methoxy-1-methylethyl)acetamide] and flufenacet [N-(4-fluorophenyl)-N-(1-methylethyl)-2-(5-(trifluoromethyl)-1,3,4- thiadiazol-2-yl)oxy] were isolated by C-18 solid-phase extraction and separated from their ethanesulfonic acid (ESA) and oxanilic acid (OXA) degradates during their elution using ethyl acetate for the parent compound, followed by methanol for the polar degradates. The parent compounds were detected using gas chromatography-mass spectrometry in selected-ion mode. The ESA and OXA degradates were detected using high-performance liquid chromatography-electrospray mass spectrometry (HPLC-ESPMS) in negative-ion mode. The method detection limits for a 123-mL sample ranged from 0.01 to 0.07 ??g/L. These methods are compatible with existing methods and thus allow for analysis of 17 commonly used herbicides and 18 of their degradation compounds with one extraction. In a study of herbicide transport near the mouth of the Mississippi River during 1999 and 2000, dimethenamid and its ESA and OXA degradates were detected in surface water samples during the annual spring flushes. For flufenacet, the only detections at the study site were for the ESA degradates in samples collected at the peak of the herbicide spring flush in 2000. The low frequency of detections in surface water likely is due to dimethenamid and flufenacet being relatively new herbicides. In addition, detectable amounts of the stable degradates have not been detected in ground water.

  13. Measurement of aspartic acid in oilseed rape leaves under herbicide stress using near infrared spectroscopy and chemometrics.

    PubMed

    Zhang, Chu; Kong, Wenwen; Liu, Fei; He, Yong

    2016-01-01

    Oilseed rape is used as both food and a renewable energy resource. Physiological parameters, such as the amino acid aspartic acid, can indicate the growth status of oilseed rape. Traditional detection methods are laborious, time consuming, costly, and not usable in the field. Here, we investigate near infrared spectroscopy (NIRS) as a fast and non-destructive detection method of aspartic acid in oilseed rape leaves under herbicide stress. Different spectral pre-processing methods were compared for optimal prediction performance. The variable selection methods were applied for relevant variable selection, including successive projections algorithm (SPA), Monte Carlo-uninformative variable elimination (MC-UVE) and random frog (RF). The selected effective wavelengths (EWs) were used as input by multiple linear regression (MLR), partial least squares (PLS) and least-square support vector machine (LS-SVM). The best predictive performance was achieved by SPA-LS-SVM (Raw) model using 22 EWs, and the prediction results were Rp = 0.9962 and RMSEP = 0.0339 for the prediction set. The result indicated that NIR combined with LS-SVM is a powerful new method to detect aspartic acid in oilseed rape leaves under herbicide stress. PMID:27441244

  14. FT IR, FT-Raman spectra and chemical computations of herbicide 2-phenoxy propionic acid - A DFT approach

    NASA Astrophysics Data System (ADS)

    Joselin Beaula, T.; James, C.

    2014-03-01

    FT IR and FT Raman spectra of herbicidal molecule 2-phenoxy propionic acid have been recorded and analyzed with the aid of normal coordinate analysis and DFT methods. Stability of the molecule arising from hyperconjugative interactions has been probed using NBO analysis. Predicted electronic absorption spectrum from TD-DFT calculation has been compared with the UV-vis spectrum. HOMO-LUMO, Mulliken population analysis and atomic charges, thermodynamic calculation and aromaticity were also calculated. From the PES scan the most stable geometry has been determined. ESP has been mapped over the electron density to obtain information about the size, shape, charge density distribution and chemical reactivity of the molecule.

  15. NOVEL HERBICIDES

    EPA Science Inventory

    Low-dose, high-potency herbicides are defined as those herbicides with a maximum label application rate of 0.5 pounds of active ingredient per acre. Several classes of chemicals fall into this category, including the acetolactate synthase (ALSase) inhibitor herbicides, imidazoli...

  16. How benthic diatoms within natural communities respond to eight common herbicides with different modes of action.

    PubMed

    Wood, Rebecca J; Mitrovic, Simon M; Lim, Richard P; Kefford, Ben J

    2016-07-01

    Herbicides are common pollutants of rivers in agricultural regions. These contaminants include various types of chemicals with different modes of toxic action. Herbicides can have toxic effects on freshwater benthic diatoms, the base of the aquatic food web. We examined the effects of (non-mixture) herbicide exposure to the health of diatoms for eight common herbicides with three different modes of action; the photosystem II (PSII) inhibitors: atrazine, simazine, hexazinone, tebuthiuron and diuron; two auxinic herbicides: MCPA and 2,4-D; and the EPSP synthase inhibitor: glyphosate. Benthic diatoms within riverine communities were exposed to each herbicide in rapid toxicity tests at concentrations of 50, 200 and 500μgL(-1). The most sensitive taxa were Gomphonema spp. and Encyonema gracilis. Navicula cryptotenella was the most tolerant to herbicide exposure. There was no significant effect of the different herbicide modes of action at the community level. Herbicide mode of action did not alter which taxa were most sensitive within the community and sensitivity rankings of the dominant diatom taxa were similar for each of the eight herbicides. The consistency of the results between herbicides suggests that freshwater benthic diatoms may be suitable in situ indicators for detecting the toxicity of herbicides with differing modes of action. PMID:27037885

  17. Contamination of rice field water with sulfonylurea and phenoxy herbicides in the Muda Irrigation Scheme, Kedah, Malaysia.

    PubMed

    Ismail, B S; Prayitno, S; Tayeb, M A

    2015-07-01

    The purpose of the present study was to investigate the potential risk of herbicide contamination (2,4-dichlorophenoxy (2,4-D), 2-methyl-4-chlorophenoxyacetic acid (MCPA), metsulfuron, bensulfuron, and pyrazosulfuron) in the rice fields of the Muda Irrigation Scheme, Kedah, Malaysia. The study included two areas with different irrigation water sources namely non-recycled (N-RCL) and recycled (RCL) water. Periodic water sampling was carried out from the drainage canals during the planting period of the wet season 2006/2007 and dry season 2007. The HPLC-UV was used to detect herbicide residues in the water samples collected from the rice fields. The results showed that the concentration of sulfonylurea herbicides such as bensulfuron and metsulfuron in the rice field was 0.55 and 0.51 μg/L, respectively. The potential risk of contamination depended on the actual dosage of each herbicide applied by farmers to their rice fields. The potential risk of water pollution by the five herbicides studied in the area with RCL water tended to be more widespread compared to the area with N-RCL water due to surface water runoff with higher levels of weedicides to the surrounding areas. During the two seasons, 50-73% of the water samples collected from the area receiving RCL water contained the five herbicides studied at concentrations of more than 0.05 μg/L, and this percentage was higher than that from the areas receiving N-RCL water (45-69%). During the wet season, the overall total mean concentration of the eight herbicides found in the samples collected from the area with RCL water (6.27 μg/L) was significantly higher (P < 0.01) than that from the area receiving N-RCL water (2.39 μg/L). Meanwhile, during the dry season, there was no significant difference (P > 0.05) in the herbicide concentrations between the areas receiving RCL (6.16 μg/L) and N-RCL water (7.43 μg/L) water. PMID:26045037

  18. Synthesis and structure--activity relationships of substituted cinnamic acids and amide analogues: a new class of herbicides.

    PubMed

    Vishnoi, Shipra; Agrawal, Vikash; Kasana, Virendra K

    2009-04-22

    In the present investigation, substituted cinnamic acids (3-hydroxy, 4-hydroxy, 2-nitro, 3-nitro, 4-nitro, 3-chloro, and 4-methoxy) and their amide analogues with four different types of substituted anilines have been synthesized. The synthesized compounds have been screened for their germination inhibition activity on radish (Raphanus sativus L. var. Japanese White) seeds at 50, 100, and 200 ppm concentrations, and the activity was compared with standard herbicide, metribuzin formulation (sencor). Significant activity was exhibited by all of the compounds. It was observed that with the increase in concentration of the test solution, the activity also increased. All of the compounds showed more than 70% inhibition at 100 ppm concentration except 4-hydroxy cinnamanilide. The compound, 2-chloro (4'-hydroxy) cinnamanilide was the best among the tested compounds, and it was found to be at par with the standard, metribuzin at all concentrations. Thus, it can be concluded that substituted cinnamic acids and their amide analogues may be developed as potential herbicides. PMID:19368353

  19. Internal energy distribution of carboxylate negative-ions of the herbicide diclofop acid in the gas-phase

    NASA Astrophysics Data System (ADS)

    Headley, J. V.; Peru, K. M.

    1997-11-01

    Unimolecular dissociations of diclofop acid and three of its esters were studied using electron capture negative-ion mass spectrometry, to determine to what extent the gas-phase chemistry correlated with transformation products reported for the herbicide in soils and microbial biofilms. Electron capture of the trimethylsilyl (TMS) and pentafluorobenzyl (PFB) esters along with H+ abstraction of diclofop acid were used to form the carboxylate ion at m / z 325. The degree of dissociation of this ion was strongly dependent on the relative distribution of internal energies, chemical nature and size of the ester group. For carboxylate ions formed with relatively low distribution of internal energies (PFB ester), elimination of HCl only was the preferred pathway. In contrast, m / z 325 from the TMS ester and diclofop acid, underwent loss of Cl, followed by loss of HCl to give m / z 254 with some direct loss of HCl for the TMS ester. For carboxylate ions formed with little or no internal energy under electrospray ionization, no unimolecular dissociations were observed. However, a wide range of product-ions were observed for the latter using collision-induced dissociations. For the methyl ester there was a preponderance for initial formation of a chlorodibenzofuran oxide ion (m / z 217) instead of electron attachment on the carbonyl function. The ion (m / z 217) was also prevalent for fragmentation of m / z 253 produced directly by electron capture of diclofop acid and the TMS ester. In general, the gas-phase ion chemistry correlated well with the distribution of some transformation products reported in the literature for the herbicide in soils and microbial biofilms.

  20. QUANTITATION OF ABERRANT INTERLOCUS T-CELL RECEPTOR REARRANGEMENTS IN MOUSE THYMOCYTES AND THE EFFECT OF THE HERBICIDE 2,4- DICHLOROPHENOXYACETIC ACID

    EPA Science Inventory

    Quantitation of aberrant interlocus T-cell receptor rearrangements in mouse thymocytes and the effect of the herbicide 2,4- Dichlorophenoxyacetic acid

    Small studies in human populations have suggested a correlation between the frequency of errors in antigen receptor gene a...

  1. Analysis of phosphorus-containing amino acid-type herbicides by sheathless capillary electrophoresis/electrospray ionization-mass spectrometry using a high sensitivity porous sprayer.

    PubMed

    Kawai, Mio; Iwamuro, Yoshiaki; Iio-Ishimaru, Reiko; Chinaka, Satoshi; Takayama, Nariaki; Hayakawa, Kazuichi

    2011-01-01

    We describe a new practical capillary electrophoresis/electrospray ionization-mass spectrometry (CE/ESI-MS) method for the forensic analysis of phosphorus-containing amino acid-type herbicides, glyphosate (GLYP), glufosinate (GLUF) and bialaphos (BIAL). A new sheathless interface, a high sensitivity porous sprayer (HSPS), was used in this study. The limits of detections of GLYP, GLUF and BIAL were 7.6, 0.61 and 0.57 pg, respectively. These values were 4-36 times lower than these obtained by conventional CE/ESI-MS using a sheath liquid. The developed method was successfully applied to the analysis of beverages spiked with the herbicides. PMID:21828926

  2. A review of methods for the analysis of orphan and difficult pesticides: glyphosate, glufosinate, quaternary ammonium and phenoxy acid herbicides, and dithiocarbamate and phthalimide fungicides.

    PubMed

    Raina-Fulton, Renata

    2014-01-01

    This article reviews the chromatography/MS methodologies for analysis of pesticide residues of orphan and difficult chemical classes in a variety of sample matrixes including water, urine, blood, and food. The review focuses on pesticide classes that are not commonly included in multiresidue analysis methods such as highly polar or ionic herbicides including glyphosate, glufosinate, quaternary ammonium, and phenoxy acid herbicides, and some of their major degradation or metabolite products. In addition, dithiocarbamate and phthalimide fungicides, which are thermally unstable and have stability issues in some solvents or sample matrixes, are also examined due to their special needs in residue analysis. PMID:25145125

  3. Vibrational spectra and natural bond orbital analysis of the herbicidal molecule 2(4-chlorophenoxy)-2-methyl propionic acid

    NASA Astrophysics Data System (ADS)

    Monicka, J. Clemy; James, C.

    2011-02-01

    The herbicide 2(4-chlorophenoxy)-2-methyl propionic acid (MCPP) has been subjected to NIR FT-Raman and infrared spectral studies. The optimized molecular structure, vibrational wavenumbers, IR intensities and Raman activities have been calculated by using density functional method (B3LYP) with the standard 6-31G(d) basis set. The calculated molecular geometry has been compared with the XRD data. The detailed assignments of the normal modes have been performed based on the potential energy distribution (PED) following the scaled quantum mechanical force field (SQMFF) methodology. The IR and Raman spectra have been plotted for the calculated wavenumbers. The simulated spectra satisfactorily coincide with the experimental spectra. The strong hyperconjugative interaction and charge delocalization that leads to the stability of the molecule have been investigated with the aid of natural bond orbital (NBO) analysis.

  4. Both foliar and residual applications of herbicides that inhibit amino acid biosynthesis induce alternative respiration and aerobic fermentation in pea roots.

    PubMed

    Armendáriz, O; Gil-Monreal, M; Zulet, A; Zabalza, A; Royuela, M

    2016-05-01

    The objective of this work was to ascertain whether there is a general pattern of carbon allocation and utilisation in plants following herbicide supply, independent of the site of application: sprayed on leaves or supplied to nutrient solution. The herbicides studied were the amino acid biosynthesis-inhibiting herbicides (ABIH): glyphosate, an inhibitor of aromatic amino acid biosynthesis, and imazamox, an inhibitor of branched-chain amino acid biosynthesis. All treated plants showed impaired carbon metabolism; carbohydrate accumulation was detected in both leaves and roots of the treated plants. The accumulation in roots was due to lack of use of available sugars as growth was arrested, which elicited soluble carbohydrate accumulation in the leaves due to a decrease in sink strength. Under aerobic conditions, ethanol fermentative metabolism was enhanced in roots of the treated plants. This fermentative response was not related to a change in total respiration rates or cytochrome respiratory capacity, but an increase in alternative oxidase capacity was detected. Pyruvate accumulation was detected after most of the herbicide treatments. These results demonstrate that both ABIH induce the less-efficient, ATP-producing pathways, namely fermentation and alternative respiration, by increasing the key metabolite, pyruvate. The plant response was similar not only for the two ABIH but also after foliar or residual application. PMID:26560850

  5. Determination of Chlorophenoxy Acid Methyl Esters and Other Chlorinated Herbicides by GC High-resolution QTOFMS and Soft lonization

    PubMed Central

    Lopez-Avila, Viorica; Roach, Patrick; Urdahl, Randall

    2015-01-01

    Gas chromatography with quadrupole time-of-flight mass spectrometry (GC-QTOFMS) and soft ionization generated by a rare-gas plasma is described here for the determination of various chlorophenoxy acid methyl esters and a few chlorinated herbicides. This plasma-based, wavelength-selectable ionization source, which can use Xe, Kr, Ar, Ne, or He as the plasma gas, enables ionization of GC-amenable compounds with ionization energies below 8.4, 10, 11.6, 16.5, or 22.4 eV, respectively. The advantages of soft ionization include enhanced molecular ions, reduced fragmentation, and reduced background noise as compared to electron ionization. In the study presented here for two plasma gases, we demonstrate that Kr plasma, which is softer than Ar plasma, yields molecular ions with a relative intensity >60% for 11 of the 16 test compounds. When using this “tunable” plasma to ionize the analytes, there is the possibility for selective ionization and less fragmentation, which may lead to increased sensitivity and may help structure elucidation, especially when using high-resolution mass spectrometry that generates accurate masses within a few parts per million (ppm) mass errors. Data generated with the Ar plasma and real matrices such as a peppermint extract, a plum extract, and an orange peel extract, spiked with 16 test compounds, indicate that the test compounds can be detected at 1–10 pg/μL of extract, and compounds such as menthone, limonene, eucalyptol, pinene, caryophylene, and other C15H24 isomers, which are present in the peppermint and the orange peel extracts at ppm to percent levels, do not appear to interfere with the determination of the chlorophenoxy acid methyl esters or the chlorinated herbicides, although there were matrix effects when the test compounds were spiked at 1–10 pg/μL of extract. PMID:25698878

  6. Specific and differential inhibition of very-long-chain fatty acid elongases from Arabidopsis thaliana by different herbicides

    PubMed Central

    Trenkamp, Sandra; Martin, William; Tietjen, Klaus

    2004-01-01

    In higher plants, very-long-chain fatty acids (VLCFAs) are the main constituents of hydrophobic polymers that prevent dessication at the leaf surface and provide stability to pollen grains. Of the 21 genes encoding VLCFA elongases (VLCFAEs) from Arabidopsis thaliana, 17 were expressed heterologously in Saccharomyces cerevisiae. Six VLCFAEs, including three known elongases (FAE1, KCS1, and KCS2) and three previously uncharacterized gene products (encoded by At5g43760, At1g04220, and At1g25450) were found to be enzymatically active with endogenous yeast fatty acid substrates and to some extent with externally supplied unsaturated substrates. The spectrum of VLCFAs accumulated in expressing yeast strains was determined by gas chromatography/mass spectrometry. Marked specificity was found among elongases tested with respect to their elongation products, which encompassed saturated and monounsaturated fatty acids 20–30 carbon atoms in length. The active VLCFAEs revealed highly distinct patterns of differential sensitivity to oxyacetamides, chloroacetanilides, and other compounds tested, whereas yeast endogenous VLCFA production, which involves its unrelated elongase (ELO) in sphingolipid synthesis, was unaffected. Several compounds inhibited more than one VLCFAE, and some inhibited all six active enzymes. These findings pinpoint VLCFAEs as the target of the widely used K3 class herbicides, which have been in commercial use for 50 years, provide important clues as to why spontaneous resistance to this class is rare, and point to complex patterns of substrate specificity and product spectrum among members of the Arabidopsis VLCFAE family. PMID:15277688

  7. Degradation and enantiomeric fractionation of mecoprop in soil previously exposed to phenoxy acid herbicides - New insights for bioremediation.

    PubMed

    Frková, Zuzana; Johansen, Anders; de Jonge, Lis Wollesen; Olsen, Preben; Gosewinkel, Ulrich; Bester, Kai

    2016-11-01

    Phenoxy acid-contaminated subsoils are common as a result of irregular disposal of residues and production wastes in the past. For enhancing in situ biodegradation at reducing conditions, biostimulation may be an effective option. Some phenoxy acids were marketed in racemic mixtures, and biodegradation rates may differ between enantiomers. Therefore, enantio-preferred degradation of mecoprop (MCPP) in soil was measured to get in-depth information on whether amendment with glucose (BOD equivalents as substrate for microbial growth) and nitrate (redox equivalents for oxidation) can stimulate bioremediation. The degradation processes were studied in soil sampled at different depths (3, 4.5 and 6m) at a Danish urban site with a history of phenoxy acid contamination. We observed preferential degradation of the R-enantiomer only under aerobic conditions in the soil samples from 3- and 6-m depth at environmentally relevant (nM) MCPP concentrations: enantiomer fraction (EF)<0.5. On the other hand, we observed preferential degradation of the S-enantiomer in all samples and treatments at elevated (μM) MCPP concentrations: EF>0.5. Three different microbial communities were discriminated by enantioselective degradation of MCPP: 1) aerobic microorganisms with little enantioselectivity, 2) aerobic microorganisms with R-selectivity and 3) anaerobic denitrifying organisms with S-selectivity. Glucose-amendment did not enhance MCPP degradation, while nitrate amendment enhanced the degradation of high concentrations of the herbicide. PMID:27432728

  8. Impacts of 2,4-dichlorophenoxyacetic acid aquatic herbicide formulations on reproduction and development of the fathead minnow (Pimephales promelas).

    PubMed

    DeQuattro, Zachary A; Karasov, William H

    2016-06-01

    The authors studied the effects of 2 formulations of 2,4-dichlorophenoxyacetic acid, dimethylamine salt (2,4-D) herbicide on fathead minnow reproduction, embryonic development, and larval survival. Groups of reproductively mature fathead minnows were exposed for 28 d to 0.00 ppm, 0.05 ppm, 0.50 ppm, and 2.00 ppm 2,4-D (target) in a flow-through system. Weedestroy® AM40 significantly (p ≤ 0.05) depressed male tubercle presence and significantly increased female gonadosomatic index, and there were statistical trends (0.05 ≤ p ≤ 0.10) for effects on fecundity and hepatic vitellogenin mRNA expression in females and males. The herbicide DMA® 4 IVM also significantly depressed male tubercle presence. Gonads of females exposed to DMA 4 IVM exhibited significantly depressed stage of oocyte maturation, significantly increased severity of oocyte atresia, and a significant presence of an unidentified tissue type. Also, DMA 4 IVM significantly decreased larval survival. It had no impact on hepatic vitellogenin mRNA expression or gonadosomatic index. No significant effects on fertilization, hatchability, or embryonic development were observed in either trial. The formulations tested exhibited different toxicological profiles from pure 2,4-D. These data suggest that the formulations have the potential for endocrine disruption and can exert some degree of chronic toxicity. The present use of 2,4-D formulations in lake management practices and their permitting based on the toxicological profile of 2,4-D pure compound should be reconsidered. Environ Toxicol Chem 2016;35:1478-1488. © 2015 SETAC. PMID:26510165

  9. Dachtal Isomers and Acidic Herbicides and Pesticides in Eggs of Osprey (Pandion haliaetus) from the Seattle and Everett Areas, Washington, U.S.A

    USGS Publications Warehouse

    Chu, S.; Henny, Charles J.; Kaiser, James L.; Drouillard, K.G.; Haffner, G.D.; Letcher, R.J.

    2007-01-01

    Current-use chlorophenoxy herbicides including 2,4-dichlorophenoxyacetic acid, dicamba, triclopyr, dicamba, dimethyl tetrachloroterephthalate (DCPA or dacthal), and the metabolite of pyrethroids, 3-phenoxybenzoic acid (3-PBA), and the fungicide, chlorothalonil, were investigated in the eggs of osprey (Pandion haliaetus) that were collected from 15 sites from five study areas Puget Sound/Seattle area of Washington State, USA. DCPA differs from acidic chlorophenoxy herbicides, and is not readily hydrolyzed to free acid or acid metabolites, and thus we developed a new method. Of the 12 chlorophenoxy herbicides and chlorothalonil analyzed only DCPA could be quantified at six of these sites (2.0 to 10.3 pg/g fresh weight). However, higher levels (6.9 to 85.5 pg/g fresh weight) of the unexpected DCPA structural isomer, dimethyl tetrachlorophthalate (diMe-TCP) were quantified in eggs from all sites. diMe-TCP concentrations tended to be higher in eggs from the Everett Harbor area. As diMe-TCP is not an industrial product, and not commercially available, the source of diMe-TCP is unclear. Regardless, these findings indicate that DCPA and diMe-TCP can be accumulated in the food chain of fish-eating osprey, and transferred in ovo to eggs, and thus may be of concern to the health of the developing chick and the general reproductive health of this osprey population.

  10. The discovery of Arylex™ active and Rinskor™ active: Two novel auxin herbicides.

    PubMed

    Epp, Jeffrey B; Alexander, Anita L; Balko, Terry W; Buysse, Ann M; Brewster, William K; Bryan, Kristy; Daeuble, John F; Fields, Stephen C; Gast, Roger E; Green, Renard A; Irvine, Nicholas M; Lo, William C; Lowe, Christian T; Renga, James M; Richburg, John S; Ruiz, James M; Satchivi, Norbert M; Schmitzer, Paul R; Siddall, Thomas L; Webster, Jeffery D; Weimer, Monte R; Whiteker, Gregory T; Yerkes, Carla N

    2016-02-01

    Multiple classes of commercially important auxin herbicides have been discovered since the 1940s including the aryloxyacetates (2,4-D, MCPA, dichlorprop, mecoprop, triclopyr, and fluroxypyr), the benzoates (dicamba), the quinoline-2-carboxylates (quinclorac and quinmerac), the pyrimidine-4-carboxylates (aminocyclopyrachlor), and the pyridine-2-carboxylates (picloram, clopyralid, and aminopyralid). In the last 10 years, two novel pyridine-2-carboxylate (or picolinate) herbicides were discovered at Dow AgroSciences. This paper will describe the structure activity relationship study that led to the discovery of the 6-aryl-picolinate herbicides Arylex™ active (2005) and Rinskor™ active (2010). While Arylex was developed primarily for use in cereal crops and Rinskor is still in development primarily for use in rice crops, both herbicides will also be utilized in additional crops. PMID:26321602

  11. Rapid and sensitive determination of phosphorus-containing amino acid herbicides in soil samples by capillary zone electrophoresis with diode laser-induced fluorescence detection.

    PubMed

    Orejuela, Eva; Silva, Manuel

    2005-12-01

    A straightforward and sensitive method has been developed for the analysis of phosphorus-containing amino acid herbicides (glufosinate and aminomethylphosphonic acid, the major metabolite of glyphosate) in soil samples. For this purpose, the analytical features of two indocyanine fluorescent dyes, sulfoindocyanine succinimidyl ester (Cy5) and 1-ethyl-1-[5-(N-succinimidyl-oxycarbonyl)pentyl]-3,3,3,3-tetramethyl-indodicarbocyanine chloride, as labeling reagents for the determination of these herbicides by CZE with diode LIF detection were investigated. Practical aspects related to the labeling chemistry and CZE separation showed that the two probes behave similarly, Cy5 being the best choice for the determination of these herbicides on account of its higher sensitivity. The optimum procedure includes a derivatization step of the pesticides at 25 degrees C for 30 min and direct injection to CZE analysis, which is conducted within about 14 min using ACN in the running buffer. The lowest detectable analyte concentration ranged from 0.025 to 0.18 microg/L with a precision of 3.6-5.4%. These results indicate that indocyanine fluorescence dyes are useful as rapid and sensitive labels for the determination of these herbicides when compared with typical fluorescein dyes such as FITC and 5-(4,6-dichloro-s-triazin-2-ylamino) fluorescein, because they provide faster labeling reactions even at room temperature and the excess of reagent practically does not interfere the determination. Finally, the Cy5 method was successfully applied to soil samples without a preliminary clean-up procedure, and the herbicides were measured without any interference from coexisting substances. The recoveries of these compounds in these samples at fortification levels of 100-500 ng/g were 90-93%. PMID:16259012

  12. Long-term sub-lethal effects of low concentration commercial herbicide (glyphosate/pelargonic acid) formulation in Bryophyllum pinnatum.

    PubMed

    Pokhrel, Lok R; Karsai, Istvan

    2015-12-15

    Potential long-term (~7months) sub-lethal impacts of soil-applied low levels of Roundup herbicide formulation were investigated in a greenhouse environment using the vegetative clones of succulent non-crop plant model, Bryophyllum pinnatum (Lam.) Oken. An eleven day LC50 (concentration that killed 50% of the plants) was found to be 6.25% (~1.25mg glyphosate/mL and 1.25mg pelargonic acid/mL combined), and complete mortality occurred at 12.5%, of the field application rate (i.e., ~20mg glyphosate/mL and 20mg pelargonic acid/mL as active ingredients). While sub-lethal Roundup (1-5%) exposures led to hormesis-characterized by a significant increase in biomass and vegetative reproduction, higher concentrations (≥6.25%) were toxic. A significant interaction between Roundup concentrations and leaf biomass was found to influence the F1 plantlets' biomass. Biomass asymmetry generally increased with increasing Roundup concentrations, indicating that plants were more stressed at higher Roundup treatments but within the low-dose regime (≤5% of the as-supplied formulation). While leaf apex region demonstrated higher reproduction with lower biomass increase, leaf basal area showed lower reproduction with greater biomass increase, in plantlets. The results suggest long-term exposures to drifted low levels of Roundup in soil may promote biomass and reproduction in B. pinnatum. PMID:26311583

  13. Quantitative analysis of total amino acid in barley leaves under herbicide stress using spectroscopic technology and chemometrics.

    PubMed

    Bao, Yidan; Kong, Wenwen; He, Yong; Liu, Fei; Tian, Tian; Zhou, Weijun

    2012-01-01

    Visible and near infrared (Vis/NIR) spectroscopy were employed for the fast and nondestructive estimation of the total amino acid (TAA) content in barley (Hordeum vulgare L.) leaves. The calibration set was composed of 50 samples; and the remaining 25 samples were used for the validation set. Seven different spectral preprocessing methods and six different calibration methods (linear and nonlinear) were applied for a comprehensive prediction performance comparison. Successive projections algorithm (SPA) and regression coefficients (RC) were applied to select effective wavelengths (EWs). The results indicated that the latent variables-least-squares-support vector machine (LV-LS-SVM) model achieved the optimal performance. The prediction results by LV-LS-SVM with raw spectra were achieved with a correlation coefficients (r) = 0.937 and root mean squares error of prediction (RMSEP) = 0.530. The overall results showed that the NIR spectroscopy could be used for determination of TAA content in barley leaves with an excellent prediction precision; and the results were also helpful for on-field monitoring of barley growing status under herbicide stress during different growth stages. PMID:23202000

  14. CZE separation of amitrol and triazine herbicides in environmental water samples with acid-assisted on-column preconcentration.

    PubMed

    Arribas, Alberto Sánchez; Moreno, Mónica; Bermejo, Esperanza; Zapardiel, Antonio; Chicharro, Manuel

    2011-01-01

    A simple analytical scheme for the detection and quantification of amitrol and triazine herbicides (atrazine, ametryn and atraton) and degradation product (2-hydroxyatrazine) in environmental water samples by CZE is reported. On-column preconcentration of analytes from untreated water samples (mineral, spring, tap and river water) is accomplished by introducing an acid plug (200 mM citrate of pH 2.0) after the sample and then proceeding with the CZE separation, using 100 mM formiate buffer of pH 3.5 as running buffer and 25.0 KV as separation voltage. UV detection at 200 nm provides LODs from 50 to 300 nM in untreated samples and they were lowered tenfold by sample preconcentration by evaporation. Calculated recoveries were typically higher than 90%. Minimal detectable concentration of the electroactive amitrol could be decreased about 20-fold when electrochemical detection was employed by monitoring the amperometric signal at +800 mV using a carbon paste electrode (LOD of 9.6 nM, 0.81 μg/L, versus 170 nM, 14.3 μg/L, using amperometric and UV detection, respectively) in untreated water samples. PMID:21254126

  15. Common and distinct gene expression patterns induced by the herbicides 2,4-dichlorophenoxyacetic acid, cinidon-ethyl and tribenuron-methyl in wheat.

    PubMed

    Pasquer, Frédérique; Ochsner, Urs; Zarn, Jürg; Keller, Beat

    2006-12-01

    In wheat, herbicides are used to control weeds. Little is known about the changes induced in the metabolism of tolerant plants after herbicide treatment. The impact of three herbicides [2,4-dichlorophenoxyacetic acid (2,4-D), cinidon-ethyl and tribenuron-methyl] on the wheat transcriptome was studied using cDNA microarrays. Gene expression of plants grown in a controlled environment or in the field was studied between 24 h and 2 weeks after treatment. Under controlled conditions, 2,4-D induced genes of the phenylpropanoid pathway soon after treatment. Cinidon-ethyl triggered peroxidase and defence-related gene expression under controlled conditions, probably because reactive oxygen species are released by photo-oxidation of protoporphyrin-IX. The same genes were upregulated in the field as under controlled conditions, albeit at a weaker level. These results show that cinidon-ethyl specifically induces genes involved in plant defence. Under controlled conditions, tribenuron-methyl did not change the expression profile immediately after treatment, but defence-related genes were upregulated after 1 week. Sulfonylurea compounds such as tribenuron-methyl specifically inhibit acetolactate synthase and are rapidly detoxified, but the activity of some of the resulting metabolites could explain later changes in gene expression. Finally, overexpression of the isopropylmalate synthase gene, involved in branched-chain amino acid synthesis, and of defence-related genes was observed in the field after sulfonylurea treatment. PMID:17054088

  16. Exposures of 129 Preschool Children to Organochlorines, Organophosphates, Pyrethroids, and Acid Herbicides at Their Homes and Daycares in North Carolina

    PubMed Central

    Morgan, Marsha K.; Wilson, Nancy K.; Chuang, Jane C.

    2014-01-01

    Few data exist on the concurrent exposures of young children to past-use and current-use pesticides in their everyday environments. In this further analysis of study data, we quantified the potential exposures and intake doses of 129 preschool children, ages 20 to 66 months, to 16 pesticides (eight organochlorines, two organophosphates, three pyrethroids, and three acid herbicides). Environmental samples (soil, dust, outdoor air, and indoor air) and personal samples (hand wipes, solid food, and liquid food) were collected at 129 homes and 13 daycare centers in six counties in North Carolina between 2000 and 2001. α-Chlordane, γ-chlordane, heptachlor, chlorpyrifos, diazinon, cis-permethrin, trans-permethrin, and 2,4-dichlorophenoxyacetic acid (2,4-D) were detected ≥50% in two or more media in both settings. Of these pesticides, the children’s estimated median potential intake doses through dietary ingestion, nondietary ingestion, and inhalation routes were the highest for 2,4-D and cis/trans-permethrin (both 4.84 ng/kg/day), cis/trans-permethrin (2.39 ng/kg/day), and heptachlor (1.71 ng/kg/day), respectively. The children’s estimated median potential aggregate intake doses by all three routes were quantifiable for chlorpyrifos (4.6 ng/kg/day), cis/trans-permethrin (12.5 ng/kg/day), and 2,4-D (4.9 ng/kg/day). In conclusion, these children were likely exposed daily to several pesticides from several sources and routes at their homes and daycares. PMID:24705361

  17. Investigation of acute toxicity of (2,4-dichlorophenoxy)acetic acid (2,4-D) herbicide on larvae and adult Nile tilapia (Oreochromis niloticus L.).

    PubMed

    Sarikaya, Rabia; Selvi, Mahmut

    2005-09-01

    A 48h LC(50) values of (2,4-dichlorophenoxy)acetic acid (2,4-D), a widely used agricultural herbicide, were determined on the larvae and adult Nile tilapia (Oreochromis niloticus L.). Each test was repeated three times. The data obtained were statistically evaluated by the use of the E.P.A computer program based on Finney's probit analysis method and a 48h LC(50) value for Nile tilapia (O. niloticus L.) larvae and adults were found to be 28.23mg/L and 86.90mg/L, respectively in a static bioassay test system. 95% lower and upper confidence limits for the LC(50) were 22.55-32.98 and 80.67-92.80mg/L, respectively. Water temperature was 24±1°C. Behavioral changes of both tilapia life forms were examined for various herbicide concentrations. PMID:21783599

  18. Efficient removal of herbicide 2,4-dichlorophenoxyacetic acid from water using Ag/reduced graphene oxide co-decorated TiO2 nanotube arrays.

    PubMed

    Tang, Yanhong; Luo, Shenglian; Teng, Yarong; Liu, Chengbin; Xu, Xiangli; Zhang, Xilin; Chen, Liang

    2012-11-30

    A new photocatalyst, Ag nanoparticles (NPs) and reduced graphene oxide (RGO) co-decorated TiO(2) nanotube arrays (NTs) (Ag/RGO-TiO(2) NTs), was designed and facilely produced by combining electrodeposition and photoreduction processes. The structures and properties of the photocatalysts were characterized. The ternary catalyst exhibited almost 100% photocatalytic removal efficiency of typical herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) from water under simulated solar light irradiation. The photodegradation rate toward 2,4-D over Ag/RGO-TiO(2) NTs is 11.3 times that over bare TiO(2) NTs. After 10 successive cycles with 1600 min of irradiation, Ag/RGO-TiO(2) NTs maintained as high 2,4-D removal efficiency as 97.3% with excellent stability and easy recovery, which justifies the photocatalytic system a promising application for herbicide removal from water. PMID:23062512

  19. Naturally occurring amino acid derivatives with herbicidal, fungicidal or insecticidal activity.

    PubMed

    Lamberth, Clemens

    2016-04-01

    Several naturally occurring amino acid derivatives display significant activities against weeds, fungi and insects: some of them have been even commercialized and are applied as crop protection agents. The 53 most important amino acid natural products with such efficacy are presented in this review together with their natural source, mode of action and biological activity. The diversity of the manifold bacterial, fungal and plantal sources of these compounds is impressive as well as their completely different structural scaffolds, ranging from cyclopeptides via unique non-proteinogenic amino acids to peptidyl nucleosides, the broad range of target enzymes from several different biochemical pathways, which they inhibit and also the plethora of different weeds, fungi and insects they are able to control. PMID:26801938

  20. Molecular structure and vibrational assignments of 2,4-dichlorophenoxyacetic acid herbicide

    NASA Astrophysics Data System (ADS)

    Badawi, Hassan M.

    2010-09-01

    The structural stability of 2,4-dichlorophenoxyacetic acid was investigated by the DFT-B3LYP and the ab initio MP2 calculations with the 6-311G** basis set. From the calculations at both levels of theory the Cgcpp structure was predicted to be the lowest energy minimum for the acid. The DFT and the MP2 levels disagreed about the nature of the second stable structure of 2,4-dichlorophenoxyacetic acid. At the DFT-B3LYP level of calculation the planar Tttp ( transoid O dbnd C sbnd O sbnd H) and the non-planar Tgcpp ( cisoid O dbnd C sbnd O sbnd H) forms were predicted to be 0.7 and 1.5 kcal/mol, respectively higher in energy than the Cgcpp conformation. At the MP2 level the two high energy Tttp and Tgcpp forms were predicted to be 2.7 and 1.4 kcal/mol, respectively higher in energy than the ground state Cgcpp structure. The Tgcpp form was adopted as the second possible structure of 2,4-dichlorophenoxyacetic acid on the basis of the fact that the Møller-Plesset calculations account better than the DFT ones for the non-bonding O⋯H interactions. The vibrational frequencies of the lowest energy Cgcpp conformer were computed at the B3LYP level of theory and tentative vibrational assignments were provided on the basis of normal coordinate analysis and experimental infrared and Raman data.

  1. Grass roots chemistry: meta-Tyrosine, an herbicidal nonprotein amino acid

    PubMed Central

    Bertin, Cécile; Weston, Leslie A.; Huang, Tengfang; Jander, Georg; Owens, Thomas; Meinwald, Jerrold; Schroeder, Frank C.

    2007-01-01

    Fine fescue grasses displace neighboring plants by depositing large quantities of an aqueous phytotoxic root exudate in the soil rhizosphere. Via activity-guided fractionation, we have isolated and identified the nonprotein amino acid m-tyrosine as the major active component. m-Tyrosine is significantly more phytotoxic than its structural isomers o- and p-tyrosine. We show that m-tyrosine exposure results in growth inhibition for a wide range of plant species and propose that the release of this nonprotein amino acid interferes with root development of competing plants. Acid hydrolysis of total root protein from Arabidopsis thaliana showed incorporation of m-tyrosine, suggesting this as a possible mechanism of phytotoxicity. m-Tyrosine inhibition of A. thaliana root growth is counteracted by exogenous addition of protein amino acids, with phenylalanine having the most significant effect. The discovery of m-tyrosine, as well as a further understanding of its mode(s) of action, could lead to the development of biorational approaches to weed control. PMID:17940026

  2. DFT computation and experimental analysis of vibrational and electronic spectra of phenoxy acetic acid herbicides

    NASA Astrophysics Data System (ADS)

    Arul Dhas, D.; Hubert Joe, I.; Roy, S. D. D.; Balachandran, S.

    2013-05-01

    An absolute vibrational analysis has been attempted on the basis of experimental FTIR and NIR-FT Raman spectra with calculated vibrational wavenumbers and intensities of phenoxy acetic acids. The equilibrium geometry, bonding features and harmonic vibrational wavenumbers have been calculated with the help of B3LYP method with Dunning correlation consistent basis set aug-cc-pVTZ. The electronic structures of molecular fragments were described in terms of natural bond orbital analysis, which shows intermolecular Osbnd H⋯O and intramolecular Csbnd H⋯O hydrogen bonds. The electronic absorption spectra with different solvents have been investigated in combination with time-dependent density functional theory calculation. The pKa values of phenoxy acetic acids were compared.

  3. Regulation of Lipid Synthesis in Soybeans by Two Benzoic Acid Herbicides 1

    PubMed Central

    Muslih, Raad K.; Linscott, Dean L.

    1977-01-01

    The effects of 3-nitro-2,5-dichlorobenzoic acid (dinoben) and 3-amino-2,4-dichlorobenzoic acid (chloramben) on lipid formation and on the incorporation of various substrates into lipids by intact seeds and subcellular fractions of germinating soybean (Glycine max [L.] Merr. `Amsoy') were studied. Dinoben (20 μg/ml) inhibited synthesis of total lipids 67%, neutral lipids 73%, glycolipids 51%, and phospholipids 39% in germinating seeds. When polar lipids were analyzed further, inhibition of individual lipid classes was also observed. Chloramben (20 μg/ml) stimulated total lipid synthesis 25%. With the exception of the mitochondrial fraction where malonate thiokinase was absent, dinoben inhibited up to 99% the incorporation of acetate and malonate into lipids, but did not inhibit acetyl-CoA and malonyl-CoA incorporation. Chloramben stimulated the incorporation of all substrates tested into lipids by all fractions except the mitochondrial fraction when malonate was the substrate. When dinoben and chloramben were used in combinations, chloramben did not reverse the inhibitory effect of dinoben. It is concluded that the dinoben inhibitory effect is specific and is associated with the acetate and malonate thiokinase systems. The chloramben effect is stimulatory to either acetyl-CoA carboxylase or fatty acid synthetase or both. PMID:16660173

  4. Imidazolinone herbicides

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The imidazolinone herbicides are widely used to manage weeds in leguminous crops, imidazolinone-resistant crops, forestry, aquatics and rights of way. This chapter briefly describes the discovery, selectivity and biological activity of the imidazolinones. The imidazolinones were discovered in the ...

  5. Degradation of herbicide 2,4-dichlorophenoxybutanoic acid in the photolysis of [FeOH]2+ and [Fe(Ox)3]3- complexes: A mechanistic study.

    PubMed

    Pozdnyakov, Ivan; Sherin, Peter; Grivin, Vjacheslav; Plyusnin, Victor

    2016-03-01

    In the present work the Fe(III)-assisted photodegradation of the herbicide 2,4-dichlorophenoxybutanoic acid (2,4-DB) has been studied by means of stationary (308 nm) and laser flash (355 nm) photolysis. The initial quantum yield of 2,4-DB photodegradation in [FeOH](2+) and [Fe(Ox)3](3-) systems was evaluated to be 0.11 and 0.17 upon 308 nm exposure, respectively. The prolonged photolysis of [FeOH](2+) and [Fe(Ox)3](3-) systems results in the complete degradation of 2,4-DB with almost complete mineralization of herbicide and its aromatic products in the case of [FeOH](2+) photolysis and the accumulation of some persistent aromatic products in the case of [Fe(Ox)3](3-) photolysis. For both systems the main primary products of 2,4-DB photolysis determined by liquid chromatography - mass spectrometry are products of the hydroxylation, the substitution of chlorine atom to OH group, the loss of aliphatic tail and the opening of benzene ring. The obtained results indicate ROS species (mainly OH radical) to be responsible for the herbicide photodegradation. PMID:26735728

  6. Synergism of herbicide toxicity by 5-aminolevulinic acid is related to physiological and ultra-structural disorders in crickweed (Malachium aquaticum L.).

    PubMed

    Xu, Ling; Zhang, Wenfang; Ali, Basharat; Islam, Faisal; Zhu, Jinwen; Zhou, Weijun

    2015-11-01

    Selection of effective herbicides to control weeds has been one of the major objectives of scientists. This study determines the differential tolerance or susceptibility of crickweed (Malachium aquaticum L.) to various concentration combinations of 5-aminolevulinic acid (ALA) (1, 10 and 100mg/L) and propyl 4-(2-(4,6-dimethoxypyrimidin-2-yloxy)benzylamino)benzoate (ZJ0273) (100, 200, and 500mg/L). ALA was applied as pre- and post-treatment alone or in combination with ZJ0273. Results showed that ZJ0273 stress alone imposed negative effects on M. aquaticum seedling's growth, net photosynthetic rates and SPAD values, and the rate of decline was consistently increased with the increase in ZJ0273 concentration. The ZJ0273 treatment showed a gradual decrease in the activities of antioxidant enzymes peroxidase (POD), superoxide dismutase (SOD), and ascorbate peroxidase (APX), and increase in the accumulation of malondialdehyde (MDA). Changes in chloroplast swelling, increased number of plastoglobuli, disruption of thylakoid, disintegrated mitochondria and turbid nucleoplasm were noticed. Moreover, SDS-PAGE analysis of total proteins revealed that herbicide stress in the leaves was associated with the decrease or disappearance of some protein bands. Further, two-dimensional gel electrophoresis (2-DE) results showed that proteins in different spots were classified into three types for M. aquaticum. These results indicate that the combined treatment of ALA and ZJ0273 synergizes the herbicide toxicity which is different from its independent effects on M. aquaticum and thus, could improve weed control efficacy. PMID:26615151

  7. Photooxidative removal of the herbicide Acid Blue 9 in the presence of hydrogen peroxide: modeling of the reaction for evaluation of electrical energy per order (E EO).

    PubMed

    Khataee, Ali R; Khataee, Hamid R

    2008-09-01

    The present work deals with photooxidative removal of the herbicide, Acid Blue 9 (AB9), in water in the presence of hydrogen peroxide (H2O2) under UV light illumination (30 W). The influence of the basic operational parameters such as amount of H2O2, irradiation time and initial concentration of AB9 on the photodegradation efficiency of the herbicide was investigated. The degradation rate of AB9 was not appreciably high when the photolysis was carried out in the absence of H2O2 and it was negligible in the absence of UV light. The photooxidative removal of the herbicide was found to follow pseudo-first-order kinetic, and hence the figure-of-merit electrical energy per order (E Eo) was considered appropriate for estimating the electrical energy efficiency. A mathematical relation between the apparent reaction rate constant and H2O2 used was applied for prediction of the electricity consumption in the photooxidative removal of AB9. The results indicated that this kinetic model, based on the initial rates of degradation, provided good prediction of the E Eo values for a variety of conditions. The results also indicated that the UV/H2O2 process was appropriate as the effective treatment method for removal of AB9 from the contaminated wastewater. PMID:18803110

  8. Separation and quantitation of three acidic herbicide residues in tobacco and soil by dispersive solid-phase extraction and UPLC-MS/MS.

    PubMed

    Xiong, Wei; Tao, Xiaoqiu; Pang, Su; Yang, Xue; Tang, GangLing; Bian, Zhaoyang

    2014-01-01

    A method for the determination of three acidic herbicides, dicamba, 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) in tobacco and soil has been developed based on the use of liquid-liquid extraction and dispersive solid-phase extraction (dispersive-SPE) followed by UPLC-MS/MS. Two percentage of (v/v) formic acid in acetonitrile as the extraction helped partitioning of analytes into the acetonitrile phase. The extract was then cleaned up by dispersive-SPE using primary secondary amine as selective sorbents. Quantitative analysis was done in the multiple-reaction monitoring mode using stable isotope-labeled internal standards for each compound. A separate internal standard for each analyte is required to minimize sample matrix effects on each analyte, which can lead to poor analyte recoveries and decreases in method accuracy and precision. The total analysis time was <4 min. The linear range of the method was from 1 to 100 ng mL(-1) with a limit of detection of each herbicide varied from 0.012 to 0.126 ng g(-1). The proposed method is faster, more sensitive and selective than the traditional methods and more accurate and robust than the published LC-MS/MS methods. PMID:24366907

  9. Removal of 2,4-Dichlorophenolyxacetic acid (2,4-D) herbicide in the aqueous phase using modified granular activated carbon

    PubMed Central

    2014-01-01

    Background Low cost 2,4-Dichlorophenolyxacetic acid (2,4-D) widely used in controlling broad-leafed weeds is frequently detected in water resources. The main objectives of this research were focused on evaluating the feasibility of using granular activated carbon modified with acid to remove 2,4-D from aqueous phase, determining its removal efficiency and assessing the adsorption kinetics. Results The present study was conducted at bench-scale method. The influence of different pH (3–9), the effect of contact time (3–90 min), the amount of adsorbent (0.1-0.4 g), and herbicide initial concentration (0.5-3 ppm) on 2,4-D removal efficiency by the granular activated carbon were investigated. Based on the data obtained in the present study, pH of 3 and contact time of 60 min is optimal for 2,4-D removal. 2,4-D reduction rate increased rapidly by the addition of the adsorbent and decreased by herbicide initial concentration (63%). The percent of 2,4-D reduction were significantly enhanced by decreasing pH and increasing the contact time. The adsorption of 2,4-D onto the granular activated carbon conformed to Langmuir and Freundlich models, but was best fitted to type II Langmuir model (R2 = 0.999). The second order kinetics was the best for the adsorption of 2,4-D by modified granular activated carbon with R2 > 0.99. Regression analysis showed that all of the variables in the process have been statistically significant effect (p < 0.001). Conclusions In conclusion, granular activated carbon modified with acid is an appropriate method for reducing the herbicide in the polluted water resources. PMID:24410737

  10. Oxidative photodegradation of herbicide fenuron in aqueous solution by natural iron oxide α-Fe2O3, influence of polycarboxylic acids.

    PubMed

    Kribéche, Mohamed El Amine; Mechakra, Hind; Sehili, Tahar; Brosillon, Stephan

    2016-01-01

    The photodegradation of the herbicide fenuron (1,1-dimethyl-3-phenylurea) by using a natural iron oxide (NIO), α-Fe2O3, in aqueous solution at acidic pH has been undertaken. The NIO was characterized by the Raman spectroscopy method. The degradation pathways and the formation of degradation products were studied. A high-pressure mercury lamp and sunlight were employed as light source. Fenuron photodegradation using NIO with oxalic acid followed the pseudo-first-order kinetics, the optimal experimental conditions were [oxalic acid]0 = 10(-3) M and [NIO] = 0.1 g L(-1) at pH 3. A UVA/NIO/oxalic acid system led to a low fenuron half-life (60 min). The results were even better when solar light is used (30 min). The variables studied were the doses of iron oxide, of carboxylic acids, the solution pH and the effect of sunlight irradiation. The effects of four carboxylic acids, oxalic, citric, tartaric and malic acids, on the fenuron photodegradation with NIO have been investigated, oxalic acid was the most effective carboxylic acid used at pH 3. A similar trend was observed for the removal of total organic carbon (TOC), 75% of TOC was removed. The analytical study showed many aromatic intermediates, short-chain carboxylic acids and inorganic ion. PMID:26102217

  11. Solid phase extraction of phosphorus-containing amino acid-type herbicides and their metabolites from human blood with titania for determination by capillary electrophoresis.

    PubMed

    Ishiwata, Tetsuya; Ishijima, Chiho; Ohashi, Akira; Okada, Haruki; Ohashi, Kousaburo

    2007-06-01

    Phosphorus-containing amino acid-type herbicides (PAAHs) and their metabolites in human plasma and whole blood were extracted with titania and determined by capillary electrophoresis (CE). The recoveries of glyphosate (GLYP), aminomethylphosphonic acid (AMPA), gluphosinate (GLUF), and 3-methylphosphonico-propionic acid (MPPA) from human plasma were 84.6, 76.8, 90.4, and 89.6%, respectively. The recoveries of GLYP, AMPA, GLUF, and MPPA from whole blood were 79.6, 84.4, 36.9, and 31.8%, respectively. The low recoveries of GLUF and MPPA from whole blood were improved by the dilution of whole blood with water to 4-fold. PMID:17575364

  12. Herbicide Persistence in Seawater Simulation Experiments.

    PubMed

    Mercurio, Philip; Mueller, Jochen F; Eaglesham, Geoff; Flores, Florita; Negri, Andrew P

    2015-01-01

    Herbicides are detected year-round in marine waters, including those of the World Heritage listed Great Barrier Reef (GBR). The few previous studies that have investigated herbicide persistence in seawater generally reported half-lives in the order of months, and several studies were too short to detect significant degradation. Here we investigated the persistence of eight herbicides commonly detected in the GBR or its catchments in standard OECD simulation flask experiments, but with the aim to mimic natural conditions similar to those found on the GBR (i.e., relatively low herbicide concentrations, typical temperatures, light and microbial communities). Very little degradation was recorded over the standard 60 d period (Experiment 1) so a second experiment was extended to 365 d. Half-lives of PSII herbicides ametryn, atrazine, diuron, hexazinone and tebuthiuron were consistently greater than a year, indicating high persistence. The detection of atrazine and diuron metabolites and longer persistence in mercuric chloride-treated seawater confirmed that biodegradation contributed to the breakdown of herbicides. The shortest half-life recorded was 88 d for growth-regulating herbicide 2,4-D at 31°C in the dark, while the fatty acid-inhibitor metolachlor exhibited a minimum half-life of 281 d. The presence of moderate light and elevated temperatures affected the persistence of most of the herbicides; however, the scale and direction of the differences were not predictable and were likely due to changes in microbial community composition. The persistence estimates here represent some of the first appropriate data for application in risk assessments for herbicide exposure in tropical marine systems. The long persistence of herbicides identified in the present study helps explain detection of herbicides in nearshore waters of the GBR year round. Little degradation of these herbicides would be expected during the wet season with runoff and associated flood plumes

  13. Herbicide Persistence in Seawater Simulation Experiments

    PubMed Central

    Mercurio, Philip; Mueller, Jochen F.; Eaglesham, Geoff; Flores, Florita; Negri, Andrew P.

    2015-01-01

    Herbicides are detected year-round in marine waters, including those of the World Heritage listed Great Barrier Reef (GBR). The few previous studies that have investigated herbicide persistence in seawater generally reported half-lives in the order of months, and several studies were too short to detect significant degradation. Here we investigated the persistence of eight herbicides commonly detected in the GBR or its catchments in standard OECD simulation flask experiments, but with the aim to mimic natural conditions similar to those found on the GBR (i.e., relatively low herbicide concentrations, typical temperatures, light and microbial communities). Very little degradation was recorded over the standard 60 d period (Experiment 1) so a second experiment was extended to 365 d. Half-lives of PSII herbicides ametryn, atrazine, diuron, hexazinone and tebuthiuron were consistently greater than a year, indicating high persistence. The detection of atrazine and diuron metabolites and longer persistence in mercuric chloride-treated seawater confirmed that biodegradation contributed to the breakdown of herbicides. The shortest half-life recorded was 88 d for growth-regulating herbicide 2,4-D at 31°C in the dark, while the fatty acid-inhibitor metolachlor exhibited a minimum half-life of 281 d. The presence of moderate light and elevated temperatures affected the persistence of most of the herbicides; however, the scale and direction of the differences were not predictable and were likely due to changes in microbial community composition. The persistence estimates here represent some of the first appropriate data for application in risk assessments for herbicide exposure in tropical marine systems. The long persistence of herbicides identified in the present study helps explain detection of herbicides in nearshore waters of the GBR year round. Little degradation of these herbicides would be expected during the wet season with runoff and associated flood plumes

  14. The broad-leaf herbicide 2,4-dichlorophenoxyacetic acid turns rice into a living trap for a major insect pest and a parasitic wasp.

    PubMed

    Xin, Zhaojun; Yu, Zhaonan; Erb, Matthias; Turlings, Ted C J; Wang, Baohui; Qi, Jinfeng; Liu, Shengning; Lou, Yonggen

    2012-04-01

    Synthetic chemical elicitors of plant defense have been touted as a powerful means for sustainable crop protection. Yet, they have never been successfully applied to control insect pests in the field. We developed a high-throughput chemical genetics screening system based on a herbivore-induced linalool synthase promoter fused to a β-glucuronidase (GUS) reporter construct to test synthetic compounds for their potential to induce rice defenses. We identified 2,4-dichlorophenoxyacetic acid (2,4-D), an auxin homolog and widely used herbicide in monocotyledonous crops, as a potent elicitor of rice defenses. Low doses of 2,4-D induced a strong defensive reaction upstream of the jasmonic acid and ethylene pathways, resulting in a marked increase in trypsin proteinase inhibitor activity and volatile production. Induced plants were more resistant to the striped stem borer Chilo suppressalis, but became highly attractive to the brown planthopper Nilaparvata lugens and its main egg parasitoid Anagrus nilaparvatae. In a field experiment, 2,4-D application turned rice plants into living traps for N. lugens by attracting parasitoids. Our findings demonstrate the potential of auxin homologs as defensive signals and show the potential of the herbicide to turn rice into a selective catch crop for an economically important pest. PMID:22313362

  15. Chlorophenol hydroxylases encoded by plasmid pJP4 differentially contribute to chlorophenoxyacetic acid degradation.

    PubMed

    Ledger, T; Pieper, D H; González, B

    2006-04-01

    Phenoxyalkanoic compounds are used worldwide as herbicides. Cupriavidus necator JMP134(pJP4) catabolizes 2,4-dichlorophenoxyacetate (2,4-D) and 4-chloro-2-methylphenoxyacetate (MCPA), using tfd functions carried on plasmid pJP4. TfdA cleaves the ether bonds of these herbicides to produce 2,4-dichlorophenol (2,4-DCP) and 4-chloro-2-methylphenol (MCP), respectively. These intermediates can be degraded by two chlorophenol hydroxylases encoded by the tfdB(I) and tfdB(II) genes to produce the respective chlorocatechols. We studied the specific contribution of each of the TfdB enzymes to the 2,4-D/MCPA degradation pathway. To accomplish this, the tfdB(I) and tfdB(II) genes were independently inactivated, and growth on each chlorophenoxyacetate and total chlorophenol hydroxylase activity were measured for the mutant strains. The phenotype of these mutants shows that both TfdB enzymes are used for growth on 2,4-D or MCPA but that TfdB(I) contributes to a significantly higher extent than TfdB(II). Both enzymes showed similar specificity profiles, with 2,4-DCP, MCP, and 4-chlorophenol being the best substrates. An accumulation of chlorophenol was found to inhibit chlorophenoxyacetate degradation, and inactivation of the tfdB genes enhanced the toxic effect of 2,4-DCP on C. necator cells. Furthermore, increased chlorophenol production by overexpression of TfdA also had a negative effect on 2,4-D degradation by C. necator JMP134 and by a different host, Burkholderia xenovorans LB400, harboring plasmid pJP4. The results of this work indicate that codification and expression of the two tfdB genes in pJP4 are important to avoid toxic accumulations of chlorophenols during phenoxyacetic acid degradation and that a balance between chlorophenol-producing and chlorophenol-consuming reactions is necessary for growth on these compounds. PMID:16597983

  16. Comparative sorption and leaching study of the herbicides fluometuron and MCPA in a soil amended with biochar and other sorbents

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Biochar is the solid residual remaining after the thermo-chemical transformation of biomass and, because of its numerous properties; it has been proposed to be used as soil amendment. In this work, the effect of soil amendment with six biochars from different feedstocks, production, and post-product...

  17. Quantitative Distribution and Metabolism of Auxin Herbicides in Roots 1

    PubMed Central

    Scott, Peter C.; Morris, Roy O.

    1970-01-01

    The internal concentrations of four auxin herbicides— 2,4-dichlorophenoxyacetic acid, dicamba, picloram, and naphthaleneacetic acid—were measured in the roots of treated pea seedlings. Intact seedlings were immersed in solutions of labeled herbicides at concentrations sufficient to produce toxic symptoms (inhibition of elongation, radial enlargement, and lateral root proliferation). Measurements of volume and herbicide content of segments taken sequentially along the root showed that an acropetal concentration gradient of each herbicide was established within the root immediately following treatment. Although there was a net loss of herbicide in the following 24 hours, the gradient was maintained. Initially, the concentration of herbicide in the root tips exceeded that in the external medium. In support of the contention that toxic symptoms due to herbicide treatment are caused by the presence of unmetabolized chemical at the site of action, it was found that metabolism was negligible for all herbicides except naphthaleneacetic acid. PMID:16657529

  18. Spatial variation in herbicide leaching from a marine clay soil via subsurface drains

    PubMed Central

    Ulén, Barbro M; Larsbo, Mats; Kreuger, Jenny K; Svanbäck, Annika

    2013-01-01

    Background Subsurface transport via tile drains can significantly contribute to pesticide contamination of surface waters. The spatial variation in subsurface leaching of normally applied herbicides was examined together with phosphorus losses in 24 experimental plots with water sampled flow-proportionally. The study site was a flat, tile-drained area with 60% marine clay in the topsoil in southeast Sweden. The objectives were to quantify the leaching of frequently used herbicides from a tile drained cracking clay soil and to evaluate the variation in leaching within the experimental area and relate this to topsoil management practices (tillage method and structure liming). Results In summer 2009, 0.14, 0.22 and 1.62%, respectively, of simultaneously applied amounts of MCPA, fluroxypyr and clopyralid were leached by heavy rain five days after spraying. In summer 2011, on average 0.70% of applied bentazone was leached by short bursts of intensive rain 12 days after application. Peak flow concentrations for 50% of the treated area for MCPA and 33% for bentazone exceeded the Swedish no-effect guideline values for aquatic ecosystems. Approximately 0.08% of the glyphosate applied was leached in dissolved form in the winters of 2008/2009 and 2010/2011. Based on measurements of glyphosate in particulate form, total glyphosate losses were twice as high (0.16%) in the second winter. The spatial inter-plot variation was large (72–115%) for all five herbicides studied, despite small variations (25%) in water discharge. Conclusions The study shows the importance of local scale soil transport properties for herbicide leaching in cracking clay soils. © 2013 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. PMID:23658148

  19. Herbicide Transformation

    PubMed Central

    Lanzilotta, R. P.; Pramer, David

    1970-01-01

    Replacement cultures liberated 3,4-dichloroaniline (DCA) from 3,4-dichloropropionanilide (propanil). The kinetics of the conversion suggest a requirement for de novo enzyme synthesis, but the system was not influenced by chloramphenicol or puromycin. Enzyme activity was detected when acetanilide (Km = 0.195 mm) was used to replace propanil as substrate. Fungal acylamidase (E.C. 3.5.1., an aryl acylamine amidohydrolase) was concentrated by salt precipitation and characterized. The Fusarium solani acylamidase exhibited an optimum at pH 7.5 to 9.0 and was inactivated in 10 min at 50 C. The enzyme was not sensitive to methyl-carbamate or organophosphate insecticides, but the herbicide, Ramrod (N-isopropyl-2-chloroacetanilide), acted as a competitive inhibitor of acetanilide hydrolysis (Ki = 0.167 mm). Hydrolysis rates were decreased by various para substitutions of acetanilide. Chloro substitution in the acyl moiety of acetanilide also reduced the rate of hydrolysis. 3,4-Dichloroacetanilide was less susceptible to enzyme action than acetanilide, but 3,4-dichloropropionanilide was hydrolyzed much more rapidly than propionanilide. The fungal acylamidase was highly specific for N-acetylarylamines. It did not catalyze hydrolysis of formanilide, butyranilide, dicryl, Karsil, fenuron, monuron, or isopropyl-N-phenylcarbamate. It appears to differ from acylamidases that have been isolated from rice, rat liver, chick kidney, and Neurospora. PMID:5437306

  20. Single, competitive, and dynamic adsorption on activated carbon of compounds used as plasticizers and herbicides.

    PubMed

    Abdel daiem, Mahmoud M; Rivera-Utrilla, José; Sánchez-Polo, Manuel; Ocampo-Pérez, Raúl

    2015-12-15

    The main aim of this study was to investigate the single, competitive, and dynamic adsorption of phthalic acid (PA), bisphenol A (BPA), diphenolic acid (DPA), 2,4-dichlorophenoxy-acetic acid (2,4-D), and 4-chloro-2-methylphenoxyacetic acid (MCPA) on two activated carbons with different chemical natures and similar textural characteristics. The adsorption mechanism was also elucidated by analyzing the influence of solution pH and ionic strength. The activated carbons demonstrated high adsorption capacity to remove all micropollutants due to the presence of active sites on their surfaces, which increase dispersive interactions between the activated carbon graphene layers and the aromatic ring of pollutants. The adsorption capacity of the activated carbons increased in the order: DPAMCPA, which is directly related to: i) molecular size of pollutants; ii) chemical structure of pollutants, and iii) chemical properties of adsorbents. In most cases, the adsorption of contaminants is favored at acid pH (pH<5) due to the establishment of attractive electrostatic interactions. In dynamic regime, the amount of pollutant adsorbed was much higher for PA, followed by DPA, and was approximately similar for BPA, 2,4-D, and MCPA. Finally, the amount of BPA and DPA adsorbed on activated carbon decreased by around 50% and 70% in the presence of DPA and BPA, respectively, indicating that both compounds are adsorbed on the same adsorption sites of the activated carbon. PMID:26282767

  1. Photocatalytic removal of 2,4-dichlorophenoxyacetic acid herbicide on copper oxide/titanium dioxide prepared by co-precipitation method

    NASA Astrophysics Data System (ADS)

    Lee, Shu Chin; Hasan, Norhasnita; Lintang, Hendrik O.; Shamsuddin, Mustaffa; Yuliati, Leny

    2016-02-01

    In this work, suppression of the charge recombination on the titanium dioxide (TiO2) was reported by the addition of copper oxide (CuO), which led to a higher activity of TiO2 for removal of 2,4-dichlorophenoxyacetic acid (2,4-D) herbicide. A series of CuO/TiO2 with CuO loadings of 0.1-1 wt% was prepared through a co-precipitation method. X-ray diffraction patterns revealed that the presence of CuO could not be detected as the low loading amount of CuO might have good dispersion on the surface of TiO2. Diffuse reflectance UV-visible spectra suggested that low loading amount of CuO did not influence the optical property of TiO2. Fluorescence spectroscopy revealed that TiO2 possessed a dominant emission peak of 407 nm at an excitation wavelength of 218 nm. The increasing loading amount of CuO decreased the emission intensity of TiO2, suggesting the successful reduction of charge recombination. After irradiation under UV light for 1 h, CuO(0.1 wt%)/TiO2 gave the highest percentage removal of the herbicide among the samples. The optimum loading amount of CuOmight improve the charge separation and reduce the electron-hole recombination on TiO2 without blocking the active sites, thus leading to the improved photocatalytic activity. This work showed that CuO/TiO2 is a potential photocatalyst for environmental remediation.

  2. Herbicide Resistant Weed Management

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Metribuzin and rimsulfuron are the only two herbicides registered for postemergence broadleaf weed control in potatoes, and represent the two classes of herbicides, triazines and ALS inhibitors, with the most reported cases of resistant weeds world wide. Other postemergence grass herbicides belongin...

  3. Rapid determination of acid herbicides in soil by liquid chromatography with tandem mass spectrometric detection based on dispersive solid phase extraction.

    PubMed

    Kaczyński, Piotr; Łozowicka, Bożena; Jankowska, Magdalena; Hrynko, Izabela

    2016-05-15

    This study determined twenty six the highly sensitive phenoxy, pyridines, aliphatic and aromatic acid compounds in soil with a liquid chromatography tandem mass spectrometry. The samples were prepared by modified quick, easy, cheap, effective, rugged and safe (QuEChERS) analytical procedure in solid samples. Herbicides extraction effectiveness was evaluated at three different spiking levels (0.01, 0.1 and 1.0mgkg(-1)). Fourteen different dispersive solid-phase extraction (d-SPE) sorbents in clean-up step were tested. The QuEChERS protocol with acidic alumina provided the highest number of pesticides with recoveries in the 70-120% range. The soil matrix effect was evaluated and for the majority of compounds were not significant, showing suppression or enhancement (±81-123%). The precision calculated as relative standard deviation (RSD) was below 22%. The linear relation was observed in the range 0.01-2.0mgkg(-1) and the correlation coefficient R>0.999. The expanded measurement uncertainty was estimated as being on average, and was between 9% and 33%. The validated method was employed in the analysis of 309 real soil samples. PMID:26992503

  4. Solid-phase extraction of phosphorous-containing amino acid herbicides from biological specimens with a zirconia-coated silica cartridge.

    PubMed

    Watanabe, Daisuke; Ohta, Hikoto; Yamamuro, Tadashi

    2014-10-15

    We report a rapid solid-phase extraction method for glyphosate (Glyp), glufosinate (Gluf), and bialaphos (Bial) using a zirconia-coated silica cartridge, which interacts specifically with phosphorous-containing amino acid herbicides (PAAHs). We extracted PAAHs from serum and urine samples. The PAAHs were derivatized with trimethyl orthoacetate-acetic acid and analyzed by ultra-performance liquid chromatography/tandem mass spectrometry (UPLC-MS/MS). The intra-day and inter-day accuracy was within ±13% RE, the intra-day and inter-day precision was less than 12% RSD, and the total recovery was more than 60% for Glyp and more than 80% for Gluf and Bial. The linearity ranges of the calibration curves of the serum samples were 0.2-10,000μg/mL for Glyp, 0.1-1000μg/L for Gluf, and 0.5-1000μg/L for Bial; and those of the urine samples were 0.4-20,000μg/L for Glyp, 0.2-2000μg/L for Gluf, and 0.1-2000μg/L for Bial. This range covers almost all the reported poisoning cases involving these compounds, from very mild to fatal cases. The present paper offers a universal cleanup method for PAAHs in serum and urine samples for clinical and forensic analysis. PMID:25151332

  5. Degradation of chloroacetanilide herbicides: The prevalence of sulfonic and oxanilic acid metabolites in Iowa groundwaters and surface waters

    USGS Publications Warehouse

    Kalkhoff, S.J.; Kolpin, D.W.; Thurman, E.M.; Ferrer, I.; Barcelo, D.

    1998-01-01

    Water samples were collected from 88 municipal wells throughout Iowa during the summer and were collected monthly at 12 stream sites in eastern Iowa from March to December 1996 to study the occurrence of the sulfonic and oxanilic metabolites of acetochlor, alachlor, and metolachlor. The sulfonic and oxanilic metabolites were present in almost 75% of the groundwater samples and were generally present from 3 to 45 times more frequently than their parent compounds. In groundwater, the median value of the summed concentrations of acetochlor, alachlor, and metolachlor was less than 0.05 μg/L, and the median value of the summed concentrations of the six metabolites was 1.2 μg/L. All surface water samples contained at least one detectable metabolite compound. Individual metabolites were detected from 2 to over 100 times more frequently than the parent compounds. In surface water, the median value of the summed concentrations of the three parent compounds was 0.13 μg/L, and the median value of the summed concentrations of the six metabolites was 6.4 μg/L. These data demonstrate the importance of analyzing both parent compounds and metabolites to more fully understand the environmental fate and transport of herbicides in the hydrologic system.

  6. Comparative study on the biodegradability of morpholinium herbicidal ionic liquids.

    PubMed

    Ławniczak, Łukasz; Materna, Katarzyna; Framski, Grzegorz; Szulc, Alicja; Syguda, Anna

    2015-07-01

    This study focused on evaluating the toxicity as well as primary and ultimate biodegradability of morpholinium herbicidal ionic liquids (HILs), which incorporated MCPA, MCPP, 2,4-D or Dicamba anions. The studied HILs were also subjected to determination of surface active properties in order to assess their influence on toxicity and biodegradability. The study was carried out with microbiota isolated from different environmental niches: sediments from river channel, garden soil, drainage trench collecting agricultural runoff stream, agricultural soil and municipal waste repository. The obtained results revealed that resistance to toxicity and biodegradation efficiency of the microbiota increased in the following order: microbiota from the waste repository > microbiota from agricultural soil ≈ microbiota from an agricultural runoff stream > microbiota from garden soil > microbiota from the river sludge. It was observed that the toxicity of HILs increased with the hydrophobicity of the cation, however the influence of the anion was more notable. The highest toxicity was observed when MCPA was used as the anion (EC50 values ranging from 60 to 190 mg L(-1)). The results of ultimate biodegradation tests indicated that only HILs with 2,4-D as the anion were mineralized to some extent, with slightly higher values for HILs with the 4-decyl-4-ethylmorpholinium cation (10-31 %) compared to HILs with the 4,4-didecylmorpholinium cation (9-20 %). Overall, the cations were more susceptible (41-94 %) to primary biodegradation compared to anions (0-61 %). The obtained results suggested that the surface active properties of the studied HILs may influence their toxicity and biodegradability by bacteria in different environmental niches. PMID:26099357

  7. Sublethal Exposure to Commercial Formulations of the Herbicides Dicamba, 2,4-Dichlorophenoxyacetic Acid, and Glyphosate Cause Changes in Antibiotic Susceptibility in Escherichia coli and Salmonella enterica serovar Typhimurium

    PubMed Central

    Kurenbach, Brigitta; Marjoshi, Delphine; Amábile-Cuevas, Carlos F.; Ferguson, Gayle C.; Godsoe, William; Gibson, Paddy

    2015-01-01

    ABSTRACT Biocides, such as herbicides, are routinely tested for toxicity but not for sublethal effects on microbes. Many biocides are known to induce an adaptive multiple-antibiotic resistance phenotype. This can be due to either an increase in the expression of efflux pumps, a reduced synthesis of outer membrane porins, or both. Exposures of Escherichia coli and Salmonella enterica serovar Typhimurium to commercial formulations of three herbicides—dicamba (Kamba), 2,4-dichlorophenoxyacetic acid (2,4-D), and glyphosate (Roundup)—were found to induce a changed response to antibiotics. Killing curves in the presence and absence of sublethal herbicide concentrations showed that the directions and the magnitudes of responses varied by herbicide, antibiotic, and species. When induced, MICs of antibiotics of five different classes changed up to 6-fold. In some cases the MIC increased, and in others it decreased. Herbicide concentrations needed to invoke the maximal response were above current food maximum residue levels but within application levels for all herbicides. Compounds that could cause induction had additive effects in combination. The role of soxS, an inducer of the AcrAB efflux pump, was tested in β-galactosidase assays with soxS-lacZ fusion strains of E. coli. Dicamba was a moderate inducer of the sox regulon. Growth assays with Phe-Arg β-naphtylamide (PAβN), an efflux pump inhibitor, confirmed a significant role of efflux in the increased tolerance of E. coli to chloramphenicol in the presence of dicamba and to kanamycin in the presence of glyphosate. Pathways of exposure with relevance to the health of humans, domestic animals, and critical insects are discussed. PMID:25805724

  8. Agro-industrial waste: a low cost adsorbent for effective removal of 4-chloro-2-methylphenoxyacetic acid herbicide in batch and packed bed modes.

    PubMed

    Deokar, Sunil K; Mandavgane, Sachin A; Kulkarni, Bhaskar D

    2016-08-01

    The present work describes the aqueous phase removal of 4-chloro-2-methylphenoxyacetic acid herbicide by rice husk ash (RHA) using batch and packed bed adsorption techniques. The effects of dosage, initial concentration, time, pH, temperature, and particle size of adsorbent in batch compared with effects of influent concentration, flow rate, and bed height in packed bed were studied. The particle size effect reveals that the removal is dependent on chemical composition (silica and carbon content) together with BET surface area of RHA. The aptness of Langmuir isotherm to batch data indicates the favorable adsorption whereas that of Temkin isotherm informs the heterogeneous nature of RHA. The kinetics of adsorption follows the pseudo-second order and Elovich models while thermodynamics of process indicates the exothermic adsorption. Among the models applied in packed bed study, the deactivation kinetic, Yoon-Nelson and bed depth service time (BDST) models are suitable to explain the packed bed adsorption. The adsorption capacity of RHA in packed bed study is found greater than that in batch. The adsorption capacity of RHA determined by the BDST model is 3019 mg/L for 90 % saturation of bed. The adsorption capacity of RHA based on weight is ∼2.3 times and that based on surface area is ∼55.55 times greater than that of granular activated carbon. PMID:27151241

  9. Inhibition of para-Hydroxyphenylpyruvate Dioxygenase by Analogues of the Herbicide Nitisinone As a Strategy to Decrease Homogentisic Acid Levels, the Causative Agent of Alkaptonuria.

    PubMed

    Laschi, Marcella; Bernardini, Giulia; Dreassi, Elena; Millucci, Lia; Geminiani, Michela; Braconi, Daniela; Marzocchi, Barbara; Botta, Maurizio; Manetti, Fabrizio; Santucci, Annalisa

    2016-04-01

    Alkaptonuria (AKU) is a rare multisystem metabolic disease caused by deficient activity of homogentisate 1,2-dioxygenase (HGD), which leads to the accumulation of homogentisic acid (HGA). Currently, there is no treatment for AKU. The sole drug with some beneficial effects is the herbicide nitisinone (1), an inhibitor of p-hydroxyphenylpyruvate dioxygenase (4-HPPD). 1 has been used as a life-saving drug in infants with type I tyrosinemia despite severe side effects due to the buildup of tyrosine. Four clinical trials of nitisinone to treat AKU have shown that 1 consistently decreases HGA levels, but also caused the accumulation of tyrosine in blood serum. Moreover, the human preclinical toxicological data for 1 are incomplete. In this work, we performed pharmacodynamics and toxicological evaluations of 1, providing the first report of LD50 values in human cells. Intracellular tyrosinemia was also evaluated. Three additional 4-HPPD inhibitors with a more favorable profile than that of 1 in terms of IC50, LD50, and tyrosine accumulation were also identified among commercially available compounds. These may be promising starting points for the development of new therapeutic strategies for the treatment of AKU. PMID:26947423

  10. 7-Methoxy-(9H-β-Carbolin-1-il)-(E)-1-Propenoic Acid, a β-Carboline Alkaloid From Eurycoma longifolia, Exhibits Anti-Inflammatory Effects by Activating the Nrf2/Heme Oxygenase-1 Pathway.

    PubMed

    Nguyen, Hai Dang; Choo, Young-Yeon; Nguyen, Tien Dat; Nguyen, Hoai Nam; Chau, Van Minh; Lee, Jeong-Hyung

    2016-03-01

    Eurycoma longifolia is an herbal medicinal plant popularly used in Southeast Asian countries. In the present study, we show that 7-methoxy-(9H-β-carbolin-1-il)-(E)-1-propenoic acid (7-MCPA), a β-carboline alkaloid isolated from E. longifolia, exerted anti-inflammatory effects by activating the nuclear factor-E2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) pathway. 7-MCPA inhibited lipopolysaccharide (LPS)-induced production of nitric oxide (NO), prostaglandin E2 (PGE2 ), and interleukin-6 (IL-6) in RAW264.7 cells and rescued C57BL/6 mice from LPS-induced lethality in vivo. LPS-induced expression of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), and IL-6 was also significantly suppressed by treatment of 7-MCPA in RAW264.7 cells. 7-MCPA induced nuclear translocation of Nrf2 and increased transcription of its target genes, such as HO-1. Treating RAW264.7 cells with 7-MCPA increased the intracellular level of reactive oxygen species (ROS) and the phosphorylation level of p38 mitogen-activated protein kinase (MAPK); however, co-treatment with the antioxidant N-acetyl-cysteine (NAC) blocked 7-MCPA-induced p38 MAPK phosphorylation. Moreover, NAC or SB203580 (p38 MAPK inhibitor) blocked 7-MCPA-induced nuclear translocation of Nrf2, suggesting that 7-MCPA activated Nrf2 via a ROS-dependent p38 pathway. 7-MCPA induced HO-1 protein and mRNA expression and knockdown of Nrf2 with siRNA or SB203580 blocked 7-MCPA-mediated induction of HO-1 expression. Inhibiting Nrf2 or HO-1 abrogated the anti-inflammatory effects of 7-MCPA in LPS-stimulated RAW264.7 cells. We also demonstrated that 7-MCPA suppressed LPS-induced nuclear factor κB (NF-κB) activation. These results provide the first evidence that 7-MCPA exerts its anti-inflammatory effect by modulating the Nrf2 and NF-κB pathways and may be a potential Nrf2 activator to prevent or treat inflammatory diseases. PMID:26291957

  11. Adsorption of herbicidally active degradate 2-(2,4-dichloro-3-methylphenoxy)propanoic acid on an andosol.

    PubMed

    Murano, Hirotatsu; Otani, Takashi; Furubayashi, Akihiro; Yamamura, Kohji; Kobayashi, Katsuichiro; Hiradate, Syuntaro

    2008-02-27

    The adsorption of 2-(2,4-dichloro-3-methylphenoxy)propanoic acid (DMPA) on the surface horizon of a humus-rich Andosol was examined. To investigate the mechanisms of adsorption, chemically treated Andosols, such as organic matter removed Andosol, organic matter and active metals removed Andosol, and clay minerals of the Andosol, were prepared. Furthermore, humic acid was extracted from the Andosol. The mechanisms of the DMPA adsorption were identified by using those untreated and chemically treated Andosols and the humic acid. The amount of DMPA adsorbed increased with decreasing equilibrium pH value. Active surface hydroxyl groups were identified as the most important soil functional group in DMPA adsorption. The predominant mechanism of DMPA adsorption on the Andosol is a ligand-exchange reaction, in which an active surface hydroxyl on Al and/or Fe is replaced by a carboxylic group of DMPA. A comparative study revealed that the amount of DMPA adsorbed was slightly greater than that of (2,4-dichlorophenoxy)acetic acid (2,4-D), especially at equilibrium pH values below 5. This is because the octanol-water partition coefficient (log Kow) of DMPA in the equilibrium pH range is higher than that of 2,4-D, and SOM participates in the adsorption process through a hydrophobic interaction. PMID:18247538

  12. Bioactivity of Herbicides

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Weed management in most agroecosystems has become largely dependent on synthetic herbicides because of their high level efficacy and relatively low cost compared to other weed control technologies. By volume, herbicides are the most abundantly used category of pesticides applied in agriculture. Th...

  13. Herbicides and plant hormesis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Herbicide hormesis is commonly observed at sub-toxic doses of herbicides and other phytotoxins. The occurrence and magnitude of this phenomenon is influenced by plant growth stage and physiological status, environmental factors, the endpoint measured, and the timing between treatment and endpoint me...

  14. Perturbed porphyrin biosynthesis contributes to differential herbicidal symptoms in photodynamically stressed rice (Oryza sativa) treated with 5-aminolevulinic acid and oxyfluorfen.

    PubMed

    Phung, Thu-Ha; Jung, Sunyo

    2014-11-01

    This paper focuses on the molecular mechanism of deregulated porphyrin biosynthesis in rice plants under photodynamic stress imposed by an exogenous supply of 5-aminolevulinic acid (ALA) and oxyfluorfen (OF). Plants treated with 5 mM ALA or 50 µM OF exhibited differential herbicidal symptoms as characterized by white and brown necrosis, respectively, with substantial increases in cellular leakage and malondialdehyde production. Protoporphyrin IX accumulated to higher levels after 1 day of ALA and OF treatment, whereas it decreased to the control level after 2 days of ALA treatment. Plants responded to OF by greatly decreasing the levels of Mg-protoporphyrin IX (MgProto IX), MgProto IX methyl ester, and protochlorophyllide to levels lower than control, whereas their levels drastically increased 1 day after ALA treatment and then disappeared 2 days after the treatment. Enzyme activity and transcript levels of HEMA1, GSA and ALAD for ALA synthesis greatly decreased in ALA- and OF-treated plants. Transcript levels of PPO1, CHLH, CHLI, and PORB genes involving Mg-porphyrin synthesis continuously decreased in ALA- and OF-treated plants, with greater decreases in ALA-treated plants. By contrast, up-regulation of FC2 and HO2 genes in Fe-porphyrin branch was noticeable in ALA and OF-treated plants 1 day and 2 days after the treatments, respectively. Decreased transcript levels of nuclear-encoded genes Lhcb1, Lhcb6, and RbcS were accompanied by disappearance of MgProto IX in ALA- and OF-treated plants after 2 days of the treatments. Under photodynamic stress imposed by ALA and OF, tight control of porphyrin biosynthesis prevents accumulation of toxic metabolic intermediates not only by down-regulation of their biosynthesis but also by photodynamic degradation. The up-regulation of FC2 and HO2 also appears to compensate for the photodynamic stress-induced damage. PMID:25454526

  15. Adsorption and photodegradation kinetics of herbicide 2,4,5-trichlorophenoxyacetic acid with MgFeTi layered double hydroxides.

    PubMed

    Nguyen, Thi Kim Phuong; Beak, Min-wook; Huy, Bui The; Lee, Yong-Ill

    2016-03-01

    The calcined layered double hydroxides (cLDHs) Ti-doped and undoped MgFe for this study were prepared by co-precipitation method followed by calcination at 500 °C. The as-prepared samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Brunauer Emmett Teller (BET) and UV-Vis diffuse reflectance spectrum (DRS) techniques and tested for adsorption and photodegradation (including photocatalytic and photo-Fenton-like) of 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) in aqueous solutions under visible light irradiation. In the range of studied operating conditions, the as-prepared samples exhibited excellent photo-Fenton-like activity, leading to more than 80-95% degradation of 2,4,5-T at initial concentration of 100 mg L(-1) with 4 g calcined LDHs per liter, was accomplished in 360 min, while 2,4,5-T half-life time was as short as 99-182 min. The kinetics of adsorption and photodegradation of 2,4,5-T were also discussed. These results offered a green, low cost and high efficiency photocatalyst for environmental remediation. PMID:26706931

  16. 40 CFR 180.318 - 4-(2-Methyl-4-chlorophenoxy) butyric acid; tolerance for residues.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...)butanoic acid, and its metabolite MCPA, (4-chloro-2-methylphenoxy)acetic acid, in or on the following food... acid; tolerance for residues. 180.318 Section 180.318 Protection of Environment ENVIRONMENTAL... FOOD Specific Tolerances § 180.318 4-(2-Methyl-4-chlorophenoxy) butyric acid; tolerance for...

  17. Optimisation of the separation of herbicides by linear gradient high performance liquid chromatography utilising artificial neural networks.

    PubMed

    Tran, Anh T K; Hyne, Ross V; Pablo, Fleur; Day, W Roy; Doble, P

    2007-02-28

    An artificial neural network (ANN) was employed to model the chromatographic response surface for the linear gradient separation of 10 herbicides that are commonly detected in storm run-off water in agricultural catchments. The herbicides (dicamba, simazine, 2,4-D, MCPA, triclopyr, atrazine, diuron, clomazone, bensulfuron-methyl and metolachlor) were separated using reverse phase high performance liquid chromatography and detected with a photodiode array detector. The ANN was trained using the pH of the mobile phase and the slope of the acetonitrile/water gradient as input variables. A total of nine experiments were required to generate sufficient data to train the ANN to accurately describe the retention times of each of the herbicides within a defined experimental space of mobile phase pH range 3.0-4.8 and linear gradient slope 1-4% acetonitrile/min. The modelled chromatographic response surface was then used to determine the optimum separation within the experimental space. This approach allowed the rapid determination of experimental conditions for baseline resolution of all 10 herbicides. Illustrative examples of determination of these components in Milli-Q water, Sydney mains water and natural water samples spiked at 0.5-1mug/L are shown. Recoveries were over 70% for solid-phase extraction using Waters Oasis((R)) HLB 6cm(3) cartridges. PMID:19071444

  18. Coupling of Molecular Imprinted Polymer Nanoparticles by High Performance Liquid Chromatography as an Efficient Technique for Sensitive and Selective Trace Determination of 4-Chloro-2-Methylphenoxy Acetic Acid in Complex Matrices

    PubMed Central

    OMIDI, Fariborz; BEHBAHANI, Mohammad; SAMADI, Saadi; SEDIGHI, Alireza; SHAHTAHERI, Seyed Jamaleddin

    2014-01-01

    Abstract Background 4-chloro-2-methylphenoxy acetic acid (MCPA) is one of the most important pesticides which is extensively used to control weeds in arable farmland. Exposure to this compound occurs in general population and persons who occupationally handle it. The aim of this present work was the preparation of MCPA imprinting polymer and its application as a selective sample preparation technique for trace determination of MCPA in biological and environmental samples. Methods In this study, MCPA imprinting polymer was obtained by precipitation polymerization using methacrylic acid (the functional monomer), ethylene glycol dimethacrylate (the cross-linker), 2, 2’-azobisisobutyronitrile (the initiator) and MCPA (the template molecule) in acetonitrile solution. The MIP-NPs were characterized by thermogravimetric analysis and scanning electron microscopy. The optimization process was carried out applying batch method. After optimization of the parameters, affecting the adsorption and desorption of analyte, urine and different water samples were used to determine MCPA. Results Imprinted MCPA molecules were removed from the polymeric structure using acetic acid in methanol (20:80 v/v %) as the eluting solvent. Both sorption and desorption process occur within 10 min. The maximum sorbent capacity of the molecular imprinted polymer is 87.4 mg g-1. The relative standard deviation and limit of detection for water samples by introduced selective solid phase extraction were 4.8% and 0.9 μg L-1, and these data for urine samples were 4.5% and 1.60 μg L-1, respectively. Conclusion The developed method was successfully applied to determine MCPA in urine and different water samples. PMID:26060766

  19. Herbicide levels in rivers draining two prairie agricultural watersheds

    SciTech Connect

    Muir, D.C.G.; Grift, N.P.

    1987-01-01

    A monitoring survey was conducted during 1984 on the Ochre and Turtle Rivers, which flow into Dauphin Lake in western Manitoba, Canada, to determine levels of the herbicides MCPA, diclofop-methyl, dicamba, bromoxynil, 2,4-D, triallate and trifluralin which were widely used in each watershed. Triallate concentrations exceeded 4 ng/L in 50% and 10% of the 21 samples taken from each of the Turtle and Ochre River, respectively, during the period March to October 1984. Trifluralin concentrations exceeded 3 ng/L in 14% and 10% of the samples from the respective rivers. Maximum concentrations did not exceed 25 ng/L and were unrelated to changes in river flow. Bromoxynil and diclofop were detected in the Turtle River, at concentrations of 113 and 476 ng/L, respectively, following a major high water event in late June, but were undetectable (<2 and 12 ng/L, respectively) at other sampling times. Dicamba and 2,4-D were detectable.

  20. Two-dimensional hydrogen-bonded polymers in the crystal structures of the ammonium salts of phen­oxy­acetic acid, (4-fluoro­phen­oxy)acetic acid and (4-chloro-2-methyl­phen­oxy)acetic acid

    PubMed Central

    Smith, Graham

    2014-01-01

    The structures of the ammonium salts of phen­oxy­acetic acid, NH4 +·C8H6O3 −, (I), (4-fluoro­phen­oxy)acetic acid, NH4 +·C8H5FO3 −, (II), and the herbicidally active (4-chloro-2-methyl­phen­oxy)acetic acid (MCPA), NH4 +·C9H8ClO3 −·0.5H2O, (III) have been determined. All have two-dimensional layered structures based on inter-species ammonium N—H⋯O hydrogen-bonding associations, which give core substructures consisting primarily of conjoined cyclic motifs. The crystals of (I) and (II) are isomorphous with the core comprising R 1 2(5), R 1 2(4) and centrosymmetric R 4 2(8) ring motifs, giving two-dimensional layers lying parallel to (100). In (III), the water mol­ecule of solvation lies on a crystallographic twofold rotation axis and bridges two carboxyl O atoms in an R 4 4(12) hydrogen-bonded motif, creating two R 4 3(10) rings, which together with a conjoined centrosymmetric R 4 2(8) ring incorporating both ammonium cations, generate two-dimensional layers lying parallel to (100). No π–π ring associations are present in any of the structures. PMID:25552984

  1. Herbicide-resistant crops and weed resistance to herbicides.

    PubMed

    Owen, Micheal D K; Zelaya, Ian A

    2005-03-01

    The adoption of genetically modified (GM) crops has increased dramatically during the last 3 years, and currently over 52 million hectares of GM crops are planted world-wide. Approximately 41 million hectares of GM crops planted are herbicide-resistant crops, which includes an estimated 33.3 million hectares of herbicide-resistant soybean. Herbicide-resistant maize, canola, cotton and soybean accounted for 77% of the GM crop hectares in 2001. However, sugarbeet, wheat, and as many as 14 other crops have transgenic herbicide-resistant cultivars that may be commercially available in the near future. There are many risks associated with the production of GM and herbicide-resistant crops, including problems with grain contamination, segregation and introgression of herbicide-resistant traits, marketplace acceptance and an increased reliance on herbicides for weed control. The latter issue is represented in the occurrence of weed population shifts, the evolution of herbicide-resistant weed populations and herbicide-resistant crops becoming volunteer weeds. Another issue is the ecological impact that simple weed management programs based on herbicide-resistant crops have on weed communities. Asiatic dayflower (Commelina cumminus L) common lambsquarters (Chenopodium album L) and wild buckwheat (Polygonum convolvulus L) are reported to be increasing in prominence in some agroecosystems due to the simple and significant selection pressure brought to bear by herbicide-resistant crops and the concomitant use of the herbicide. Finally, evolution of herbicide-resistant weed populations attributable to the herbicide-resistant crop/herbicide program has been observed. Examples of herbicide-resistant weeds include populations of horseweed (Conyza canadensis (L) Cronq) resistant to N-(phosphonomethyl)glycine (glyphosate). An important question is whether or not these problems represent significant economic issues for future agriculture. PMID:15668920

  2. Biodegradation of a mixture of the herbicides ametryn, and 2,4-dichlorophenoxyacetic acid (2,4-D) in a compartmentalized biofilm reactor.

    PubMed

    Sandoval-Carrasco, Carlos A; Ahuatzi-Chacón, Deifilia; Galíndez-Mayer, Juvencio; Ruiz-Ordaz, Nora; Juárez-Ramírez, Cleotilde; Martínez-Jerónimo, Fernando

    2013-10-01

    In this work, an efficient degradation process for the removal of 2,4-D and ametryn, together with organic and inorganic adjuvants used in the commercial formulations of both herbicides, was developed. Although both compounds are toxic for microbial communities, ametryn is markedly more toxic than 2,4-D. In spite of this, the microbial consortium used could resist loading rates up to 31.5 mg L(-1) d(-1) of ametryn, with removal efficiencies up to 97% for both herbicides. Thus, an alternative use of this consortium could be bioaugmentation, as a tool to protect the structure and function of an activated-sludge biota against ametryn or 2,4-D shock loads. The process was carried out in a lab-scale prototype of aerobic biobarrier constructed as a compartmentalized fixed film reactor with airlift recirculation of oxygenated liquid. PMID:23566464

  3. Herbicide-resistant crops, resistant weeds, and herbicide drift

    Technology Transfer Automated Retrieval System (TEKTRAN)

    New herbicide-resistance traits in corn and soybean may bring new management challenges for fruit and vegetable growers in the Mid-Atlantic region. Herbicide-resistant crops are an important weed management technology in row crop agriculture that allow growers to apply an herbicide to control weed...

  4. ANALYTICAL MASS SPECTROMETRY OF HERBICIDES

    EPA Science Inventory

    Herbicides are chemical substances that are applied to agricultural soils, gardens, lawns, or plants to destroy or to prevent the growth of undesirable vegetation. The herbicides included in this review are generally syntehtic organic compuonds that are ingredients in commercial...

  5. Protoporphyrinogen Oxidase-Inhibiting Herbicides

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Protoporphyrinogen oxidase-inhibiting herbicides (also referred to as Protox- or PPO-inhibiting herbicides) were commercialized in the 1960s and their market share reached approximately 10% (total herbicide active ingredient output) in the late 1990’s. The wide-spread adoption of glyphosate-resista...

  6. NOVEL CHROMATOGRAPHIC SEPARATION AND CARBON SOLID PHASE EXTRACTION OF ACETANILIDE HERBICIDE DEGRADATION PRODUCTS

    EPA Science Inventory

    Six acetanilide herbicides are currently registered for use in the U.S. Over the past several years, ethanesufonic acid (ESA) and oxanilic acid (OA) degradatoin products of these acetanilide herbicides have been found in U.S. ground waters and surface waters. "Alachlor ESA and ...

  7. A follow-up study of cancer incidence among workers in manufacture of phenoxy herbicides in Denmark.

    PubMed Central

    Lynge, E.

    1985-01-01

    The purpose of this cohort study is to shed further light on the potential carcinogenic effect indicated by a Swedish case control study of the 2,4-dichlorophenol and 4-chloro-ortho-cresol based phenoxy herbicides, unlikely to be contaminated with 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD). In the present study it was the intention to include all persons employed in manufacture of phenoxy herbicides in Denmark before 1982. The predominant product was MCPA and only a very limited amount of 2,4,5-T was processed in one of the two factories included in the study. Registration of the cohort was based on company records, supplemented with data from a public pension scheme from 1964 onwards. Ninety-nine percent of registered employees could be followed up. Cancer cases were identified by linkage with the National Cancer Register. Totals of 3,390 males and 1,069 females were included in the study. In the analysis special attention was given to soft tissue sarcomas (STS) and malignant lymphomas (ML) which are the diagnostic groups indicated to be associated with exposure to phenoxy herbicides in the Swedish studies. Five cases of STS were observed among male employees in contrast to 1.84 expected cases. This result supports the Swedish observation of an increased risk of STS following exposure to phenoxy herbicides unlikely to be contaminated with 2,3,7,8-TCDD. However, several potential biases have to be taken into account in interpretation of this observation and these are discussed. Seven cases of ML were observed among male employees in contrast to 5.37 expected which does not support the Swedish observation of an excess risk. The total cancer risk among persons employed in manufacture and packaging of phenoxy herbicides was equivalent to the cancer risk in the Danish population. Among males thus employed 11 lung cancer cases were observed in contrast to 5.33 expected. Attention should be given to exposure to spray dried MCPA-sodium salt in the plants, but

  8. Vegetative reproduction and chemical control with post-emergent herbicides of field bindweed (Convolvulus arvensis L.).

    PubMed

    Gyenes, V; Béres, I; Lehoczky, E; Kazinczi, G; Nyári, A

    2005-01-01

    It is clearly seen from data that roots of Convolvulus arvensis L. have more and less intensive regenerative period during growing season. The more intensive period is in autumn, because in that time roots culminate nutrients, carbohydrate as starch and sugar. The less intensive regenerative or shoot-growing period is in spring, called "late spring bud dormancy". Experiments were conducted to get more information and further details about the regenerative capacity of roots close to and far from the collar of Convolvulus arvensis L. Root segments closer to collar have an intensive regenerative capacity than those ones further to collar. By data of Bakke et al. (1939) is well known, roots exhumed from deep soil layers are able to create shoots with low intensity. So finally we can exclaim that regenerative capacity is decreasing further to collar. Using mechanical weed control it is sufficient to till the upper layer of soil, but many times. Chemical treatments are most effective in the integrated weed control. It is clearly seen that auxin-type herbicide such as 2,4-D, fluroxipir, MCPA. dicamba give the best result. They gave 95% weed control effect used them separately or in combination with other herbicides. Combination of Banvel 480 S (dicamba) and Logran 75 WG (triasulfuron) introduced 95% weed control effect. Only one time got absolutely 100% weed control effect, in the case of Glyphosate active substance. Caused total plant destruction. Excellent result was given with the application of Pledge 50WP (flumioxazin). Herbicides mentioned above are absolutely allowed to take an important and significant part in chemical plant protection against Convolvulus arvensis L. Other herbicides like Granstar 75DF (tribenuron-methyl), Basis 75DF (rimsulfuron + tifensulfuron-methyl) and Huszár (jodosulfuron-methyl-sodium + mefenpir-diethyl) are not so effective against Convolvulus arvensis L., as compared to the previous ones. PMID:16637219

  9. Synthesis and herbicidal activities of benzothiazole N,O-acetals.

    PubMed

    Ji, Zhiqin; Zhou, Fengxing; Wei, Shaopeng

    2015-10-01

    A new series of N,O-acetals were prepared via a simple one-pot reaction by the condensation of 2-amino-methybenzothiazole with aldehydes and alcohols. The title compounds were obtained in moderate to good yields in the presence of acid catalyst. Bioassay results indicated that some synthesized compounds had good herbicidal activity against both dicotyledon and monocotyledon weeds. This investigation provided a new type of herbicidal lead compounds, as well as its facile preparation method. PMID:26318996

  10. Leaching and persistence of herbicides for kudzu (Pueraria montana) control on pine regeneration sites

    SciTech Connect

    Berisford, Yvette, C.; Bush, Parshall, B.; Taylor, John, W.

    2006-03-01

    Kudzu is an exotic vine that threatens forests in the southeastern United States. It can climb, overtop, and subsequently kill new seedlings or mature trees. Herbicides are commonly used to control kudzu; however, eradication might require retreatment for 3 to 10 yr in young stands and 7 to 10 yr for mature stands. Clopyralid, picloram, triclopyr, metsulfuron, and tebuthiuron exert various degrees of control, depending on soil type, meteorological conditions, herbicide formulation, seasonal application, characteristics of the kudzu stand, and frequency and number of herbicide. Field residue data for soil or leachate are lacking for all of these herbicides when they are used in actual forest regeneration programs in the Coastal Plain. These data are needed to assess the relative potential for the herbicides to leach into groundwater or to move off-site into sensitive ecological areas of the Coastal Plain in which sandy soils predominate and the groundwater tends to be shallow. As part of an integrated pest management program to control kudzu on forest regeneration areas at the Savannah River Site near New Ellenton, SC, five herbicides were evaluated from the standpoints of herbicide leaching, kudzu control, and plant community development. Three herbicide chemical families were represented. This included pyridinecarboxylic acid herbicides (clopyralid, picloram 1 2,4-D, and triclopyr), a sulfonylurea herbicide (metsulfuron), and a substituted urea herbicide (tebuthiuron).

  11. Weed control without herbicides

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Managing weeds without herbicides is challenging and requires an integration of tactics and a change in how weeds problems are approached. Weeds should be managed in a holistic, intentional and proactive manner. Growers that successfully manage weeds in organic systems examine why certain weed speci...

  12. Postemergence herbicides for calendula

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Calendula is an alternative oilseed crop whose seed oil is valued as a substitute for tung oil and a replacement for petroleum-based volatile organic compounds in paints and other coatings. Calendula is not yet grown extensively as an agronomic crop, and its tolerances to most herbicides are unknown...

  13. ANNUAL HERBICIDE LOADINGS

    EPA Science Inventory

    Pesticides, Herbicides, Fungicides...etc, are used for a variety of purposes, including control of household, lawn, and garden pests; for control of mosquitoes and other insect vectors of animal and human diseases; for control of brush in rangelands, on roadsides, and along power...

  14. HERBICIDES: CAROTENOID BIOSYNTHESIS INHIBITORS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The physiological functions of carotenoids are essential for the health of plants. In particular, their ability to quench excess energy due to photoexcitation of chlorophyll under high light intensity is necessary to stabilize the photosynthetic apparatus. Inhibiting this pathway with herbicides i...

  15. Brassica greens herbicide screening

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this study was to screen herbicides for potential use in brassica greens. Plots were in a RBD with 4 replications. The study was direct seeded on May 19, 2009 with a seeding rate of 272,000 seeds/acre (‘Savanna’ mustard). Treatments included trifluralin PPI + DCPA pre-emergence ap...

  16. Evolution of herbicide resistance mechanisms in grass weeds.

    PubMed

    Matzrafi, Maor; Gadri, Yaron; Frenkel, Eyal; Rubin, Baruch; Peleg, Zvi

    2014-12-01

    Herbicide resistant weeds are becoming increasingly common, threatening global food security. Here, we present BrIFAR: a new model system for the functional study of mechanisms of herbicide resistance in grass weeds. We have developed a large collection of Brachypodium accessions, the BrI collection, representing a wide range of habitats. Wide screening of the responses of the accessions to four major herbicide groups (PSII, ACCase, ALS/AHAS and EPSPS inhibitors) identified 28 herbicide-resistance candidate accessions. Target-site resistance to PSII inhibitors was found in accessions collected from habitats with a known history of herbicide applications. An amino acid substitution in the psbA gene (serine264 to glycine) conferred resistance and also significantly affected the flowering and shoot dry weight of the resistant accession, as compared to the sensitive accession. Non-target site resistance to ACCase inhibitors was found in accessions collected from habitats with a history of herbicide application and from a nature reserve. In-vitro enzyme activity tests and responses following pre-treatment with malathion (a cytochrome-P450 inhibitor) indicated sensitivity at the enzyme level, and give strong support to diclofop-methyl and pinoxaden enhanced detoxification as NTS resistance mechanism. BrIFAR can promote better understanding of the evolution of mechanisms of herbicide resistance and aid the implementation of integrative management approaches for sustainable agriculture. PMID:25443832

  17. Rationale for a natural products approach to herbicide discovery.

    PubMed

    Dayan, Franck E; Owens, Daniel K; Duke, Stephen O

    2012-04-01

    Weeds continue to evolve resistance to all the known modes of herbicidal action, but no herbicide with a new target site has been commercialized in nearly 20 years. The so-called 'new chemistries' are simply molecules belonging to new chemical classes that have the same mechanisms of action as older herbicides (e.g. the protoporphyrinogen-oxidase-inhibiting pyrimidinedione saflufenacil or the very-long-chain fatty acid elongase targeting sulfonylisoxazoline herbicide pyroxasulfone). Therefore, the number of tools to manage weeds, and in particular those that can control herbicide-resistant weeds, is diminishing rapidly. There is an imminent need for truly innovative classes of herbicides that explore chemical spaces and interact with target sites not previously exploited by older active ingredients. This review proposes a rationale for a natural-products-centered approach to herbicide discovery that capitalizes on the structural diversity and ingenuity afforded by these biologically active compounds. The natural process of extended-throughput screening (high number of compounds tested on many potential target sites over long periods of times) that has shaped the evolution of natural products tends to generate molecules tailored to interact with specific target sites. As this review shows, there is generally little overlap between the mode of action of natural and synthetic phytotoxins, and more emphasis should be placed on applying methods that have proved beneficial to the pharmaceutical industry to solve problems in the agrochemical industry. PMID:22232033

  18. A Community-Engaged Approach to Developing a Mobile Cancer Prevention App: The mCPA Study Protocol

    PubMed Central

    2016-01-01

    Background Rapid growth of mobile technologies has resulted in a proliferation of lifestyle-oriented mobile phone apps. However, most do not have a theoretical framework and few have been developed using a community-based participatory research approach. A community academic team will develop a theory-based, culturally tailored, mobile-enabled, Web-based app—the Mobile Cancer Prevention App (mCPA)—to promote adherence to dietary and physical activity guidelines. Objective The aim of this study is to develop mCPA content with input from breast cancer survivors. Methods Members of SISTAAH (Survivors Involving Supporters to Take Action in Advancing Health) Talk (N=12), treated for Stages I-IIIc breast cancer for less than 1 year, 75 years of age or younger, and English-speaking and writing, will be recruited to participate in the study. To develop the app content, breast cancer survivors will engage with researchers in videotaped and audiotaped sessions, including (1) didactic instructions with goals for, benefits of, and strategies to enhance dietary intake and physical activity, (2) guided discussions for setting individualized goals, monitoring progress, and providing or receiving feedback, (3) experiential nutrition education through cooking demonstrations, and (4) interactive physical activity focused on walking, yoga, and strength training. Qualitative (focus group discussions and key informant interviews) and quantitative (sensory evaluation) methods will be used to evaluate the participatory process and outcomes. Results Investigators and participants anticipate development of an acceptable (frequency and duration of usage) feasible (structure, ease of use, features), and accessible mobile app available for intervention testing in early 2017. Conclusions Depending on the availability of research funding, mCPA testing, which will be initiated in Miami, will be extended to Chicago, Houston, Philadelphia, and Los Angeles. PMID:26935995

  19. Herbicide resistance in Aster squamatus conferred by a less sensitive form of acetolactate synthase.

    PubMed

    Osuna, Maria D; Fischer, Albert J; De Prado, Rafael

    2003-11-01

    A biotype of Aster squamatus (Sprengel) Hieronymus with suspected resistance to the ALS-inhibiting herbicide imazapyr was detected in a chicken farm in the province of Seville, Spain, which had been treated once a year with imazapyr for 10 years. Resistance to imazapyr in this biotype was studied using dose-response experiments, absorption and translocation assays, metabolism studies and ALS activity assays. The rate of imazapyr required to inhibit A squamatus growth by 50% (ED50) was 15 times higher for the R (resistant) than for the S (susceptible) biotype. Cross-resistance existed for the ALS-inhibitors imazamox, imazethapyr, amidosulfuron, nicosulfuron, rimsulfuron, triasulfuron and tribenuron, but not for bensulfuron. Control of A squamatus using alternative herbicides was poor with clopyralid, intermediate with quinclorac, amitrole and MCPA, and excellent with 2,4-D, glufosinate and glyphosate. Absorption of [14C]imazapyr increased over time for both the R and S biotypes, and translocation from the treated leaf to shoots and roots was similar in both biotypes, with most of the radioactivity remaining in the treated leaf. No metabolites of imazapyr were detected in either biotype. Sensitivity of the ALS enzyme (target site) to imazapyr was lower for the R biotype (I50(R) = 4.28 x I50(S)). The mechanism of imazapyr resistance in this R biotype appears to be an altered ALS conferring decreased sensitivity to imazapyr at the whole-plant level. PMID:14620047

  20. Gene encoding herbicide safener binding protein

    SciTech Connect

    Walton, J.D.; Scott-Craig, J.S.

    1999-10-26

    The cDNA encoding safener binding protein (SafBP), also referred to as SBP1, is presented. The deduced amino acid sequence is provided. Methods of making and using SBP1 and SafBP to alter a plant's sensitivity to certain herbicides or a plant's responsiveness to certain safeners are also provided, as well as expression vectors, transgenic plants or other organisms transfected with vectors and seeds from the plants.

  1. Biodegradation of acetanilide herbicides acetochlor and butachlor in soil.

    PubMed

    Ye, Chang-ming; Wang, Xing-jun; Zheng, He-hui

    2002-10-01

    The biodegradation of two acetanilide herbicides, acetochlor and butachlor in soil after other environmental organic matter addition were measured during 35 days laboratory incubations. The herbicides were applied to soil alone, soil-SDBS (sodium dodecylbenzene sulfonate) mixtures and soil-HA (humic acid) mixtures. Herbicide biodegradation kinetics were compared in the different treatment. Biodegradation products of herbicides in soil alone samples were identified by GC/MS at the end of incubation. Addition of SDBS and HA to soil decreased acetochlor biodegradation, but increased butachlor biodegradation. The biodegradation half-life of acetochlor and butachlor in soil alone, soil-SDBS mixtures and soil-HA mixtures were 4.6 d, 6.1 d and 5.4 d and 5.3 d, 4.9 d and 5.3 d respectively. The biodegradation products were hydroxyacetochlor and 2-methyl-6-ethylaniline for acetochlor, and hydroxybutachlor and 2,6-diethylaniline for butachlor. PMID:12491727

  2. INTERACTION OF OZONE AND HERBICIDES IN SOYBEANS

    EPA Science Inventory

    The purpose of this investigation was to identify potentially damaging herbicide-ozone interactions on soybean so that injury could be reduced by judicious selection of herbicides and tolerant cultivars. The involvement of herbicide influence on stomatal aperture affecting ozone ...

  3. Impairment of carbon metabolism induced by the herbicide glyphosate.

    PubMed

    Orcaray, Luis; Zulet, Amaia; Zabalza, Ana; Royuela, Mercedes

    2012-01-01

    The herbicide glyphosate reduces plant growth and causes plant death by inhibiting the biosynthesis of aromatic amino acids. The objective of this work was to determine whether glyphosate-treated plants show a carbon metabolism pattern comparable to that of plants treated with herbicides that inhibit branched-chain amino acid biosynthesis. Glyphosate-treated plants showed impaired carbon metabolism with an accumulation of carbohydrates in the leaves and roots. The growth inhibition detected after glyphosate treatment suggested impaired metabolism that impedes the utilization of available carbohydrates or energy at the expected rate. These effects were common to both types of amino acid biosynthesis inhibitors. Under aerobic conditions, ethanolic fermentative metabolism was enhanced in the roots of glyphosate-treated plants. This fermentative response was not related to changes in the respiratory rate or to a limitation of the energy charge. This response, which was similar for both types of herbicides, might be considered a general response to stress conditions. PMID:21944839

  4. A composite transcriptional signature differentiates responses towards closely related herbicides in Arabidopsis thaliana and brassica napus

    EPA Science Inventory

    In this study, genome-wide expression profiling based on Affymetrix ATH1 arrays was used to identify discriminating responses of Arabidopsis thaliana to five herbicides, which contain active ingredients targeting two different branches of amino acid biosynthesis. One herbicide co...

  5. Chlorinated phenoxyacetic acids and chlorophenols in the modified Allium test.

    PubMed

    Fiskesjö, G; Lassen, C; Renberg, L

    1981-03-15

    The chlorinated phenoxyacetic acids 2-methyl-4-chlorophenoxyacetic acid (MCPA), 2,4-dichlorophenoxyacetic acid (2,4-D), 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) and 2,4,5-T butoxyethyl ester and the chlorophenols 2,4-dichlorophenol and 2,4,5-trichlorophenol were tested for genotoxicity in the modified Allium test, which is based on exposure to the test chemicals of growing onions. The mean length of growing roots were measured and chromosome damage was recorded. Of the substances tested, MCPA was the most toxic and the chlorophenoxyacetic acids were more toxic than the chlorophenols. The lower threshold values for growth retardation were below 0.1 ppm for the acids, approx. at 0.1 ppm for the ester and less than 5 ppm for the phenols. Though a monocotyledon, Allium cepa was sensitive enough to respond to even low concentrations of these dicotyledon-selecting pesticides. PMID:7460089

  6. Current state of herbicides in herbicide-resistant crops.

    PubMed

    Green, Jerry M

    2014-09-01

    Current herbicide and herbicide trait practices are changing in response to the rapid spread of glyphosate-resistant weeds. Growers urgently needed glyphosate when glyphosate-resistant crops became available because weeds were becoming widely resistant to most commonly used selective herbicides, making weed management too complex and time consuming for large farm operations. Glyphosate made weed management easy and efficient by controlling all emerged weeds at a wide range of application timings. However, the intensive use of glyphosate over wide areas and concomitant decline in the use of other herbicides led eventually to the widespread evolution of weeds resistant to glyphosate. Today, weeds that are resistant to glyphosate and other herbicide types are threatening current crop production practices. Unfortunately, all commercial herbicide modes of action are over 20 years old and have resistant weed problems. The severity of the problem has prompted the renewal of efforts to discover new weed management technologies. One technology will be a new generation of crops with resistance to glyphosate, glufosinate and other existing herbicide modes of action. Other technologies will include new chemical, biological, cultural and mechanical methods for weed management. From the onset of commercialization, growers must now preserve the utility of new technologies by integrating their use with other weed management technologies in diverse and sustainable systems. PMID:24446395

  7. Herbicide concentrations in the Mississippi River Basin-the importance of chloroacetanilide herbicide degradates.

    PubMed

    Rebich, R A; Coupe, R H; Thurman, E M

    2004-04-01

    The proportion of chloroacetanilide herbicide degradates, specifically the ethane sulfonic (ESA) and oxanilic (OA) acids, averaged 70% of the total herbicide concentration in samples from the Upper Mississippi River. In samples from the Missouri River and the Ohio River, the proportion of chloroacetanilide degradates in the total herbicide concentration was much less, 24% and 41%, respectively. The amount of tile drainage throughout the Mississippi River Basin appeared to be related to the occurrence and distribution of chloroacetanilide degradates in water samples. Pesticide concentrations in streams of the Mississippi River Basin have been well characterized. However, recent research demonstrates that in order to more fully understand the fate and transport of pesticides, the major pesticide degradates need to be included in the analysis. From March 1999 through May 2001, water samples from four major junctures of the Mississippi River Basin were collected and analyzed for a suite of herbicides and their degradate compounds. Each sampling site was selected to represent a major part of the Mississippi River: upper and lower Mississippi, Missouri and Ohio Rivers. Each basin has unique landscape variables, geology, hydrology, precipitation, and land use, which is reflected in the pesticide content at the most downstream sample site near the mouth of the Mississippi River. Atrazine was the most frequently detected herbicide (detected in 97% of the samples), followed by metolachlor (60%), and acetochlor (31%). The most frequently detected degradates were metolachlor ESA (69%), followed by deethylatrazine (62%), metolachlor OA (37%), and alachlor ESA (37%). Metolachlor ESA was detected more frequently than its parent compound (69 vs. 60%), as was alachlor ESA (37 vs. 9%). After an improvement was made in the analytical method, metolachlor ESA was detected in every sample, metolachlor OA in 89% of the samples, alachlor ESA in 84%, acetochlor ESA in 71%, and acetochlor

  8. Herbicide concentrations in the Mississippi River Basin - The importance of chloroacetanilide herbicide degradates

    USGS Publications Warehouse

    Rebich, R.A.; Coupe, R.H.; Thurman, E.M.

    2004-01-01

    The proportion of chloroacetanilide herbicide degradates, specifically the ethane sulfonic (ESA) and oxanilic (OA) acids, averaged 70% of the total herbicide concentration in samples from the Upper Mississippi River. In samples from the Missouri River and the Ohio River, the proportion of chloroacetanilide degradates in the total herbicide concentration was much less, 24% and 41%, respectively. The amount of tile drainage throughout the Mississippi River Basin appeared to be related to the occurrence and distribution of chloroacetanilide degradates in water samples. Pesticide concentrations in streams of the Mississippi River Basin have been well characterized. However, recent research demonstrates that in order to more fully understand the fate and transport of pesticides, the major pesticide degradates need to be included in the analysis. From March 1999 through May 2001, water samples from four major junctures of the Mississippi River Basin were collected and analyzed for a suite of herbicides and their degradate compounds. Each sampling site was selected to represent a major part of the Mississippi River: upper and lower Mississippi, Missouri and Ohio Rivers. Each basin has unique landscape variables, geology, hydrology, precipitation, and land use, which is reflected in the pesticide content at the most downstream sample site near the mouth of the Mississippi River. Atrazine was the most frequently detected herbicide (detected in 97% of the samples), followed by metolachlor (60%), and acetochlor (31%). The most frequently detected degradates were metolachlor ESA (69%), followed by deethylatrazine (62%), metolachlor OA (37%), and alachlor ESA (37%). Metolachlor ESA was detected more frequently than its parent compound (69 vs. 60%), as was alachlor ESA (37 vs. 9%). After an improvement was made in the analytical method, metolachlor ESA was detected in every sample, metolachlor OA in 89% of the samples, alachlor ESA in 84%, acetochlor ESA in 71%, and acetochlor

  9. Toxic and genotoxic effects of the 2,4-dichlorophenoxyacetic acid (2,4-D)-based herbicide on the Neotropical fish Cnesterodon decemmaculatus.

    PubMed

    Ruiz de Arcaute, C; Soloneski, S; Larramendy, M L

    2016-06-01

    Acute toxicity and genotoxicity of the 54.8% 2,4-D-based commercial herbicide DMA® were assayed on Cnesterodon decemmaculatus (Pisces, Poeciliidae). Whereas lethal effect was used as the end point for mortality, frequency of micronuclei (MNs), other nuclear abnormalities and primary DNA damage evaluated by the single cell gel electrophoresis (SCGE) assay were employed as end points for genotoxicity. Mortality studies demonstrated an LC50 96h value of 1008mg/L (range, 929-1070) of 2,4-D. Behavioral changes, e.g., gathering at the bottom of the aquarium, slowness in motion, slow reaction and abnormal swimming were observed. Exposure to 2,4-D within the 252-756mg/L range increased the frequency of MNs in fish exposed for both 48 and 96h. Whereas blebbed nuclei were induced in treatments lasting for 48 and 96h, notched nuclei were only induced in fish exposed for 96h. Regardless of both concentration and exposure time, 2,4-D did not induce lobed nuclei and binucleated erythrocytes. In addition, we found that exposure to 2,4-D within the 252-756mg/L range increased the genetic damage index in treatments lasting for either 48 and 96h. The results represent the first experimental evidence of the lethal and several sublethal effects, including behavioral alterations and two genotoxic properties namely the induction of MNs and primary DNA strand breaks, exerted by 2,4-D on an endemic organism as C. decemmaculatus. PMID:26950899

  10. Analytical studies on degradation mechanism of herbicide 4-chlorophenoxyacetic acid in water by gamma/H2O2 and gamma/ozone processes.

    PubMed

    Torun, Murat; Şolpan, Dilek

    2016-10-01

    Radiolytic degradation of 4-chlorophenoxyacetic acid was followed in the presence of hydrogen peroxide and ozone. The synergic effect of ozone is found to be relatively high since the amounts of detected aromatic intermediates are lower as well as the amounts of small aliphatic acids are higher. Chloride ions are one of the most important mineralization products and splitted with a yield of more than 80%. The amounts of small aliphatic acids formed in the last step before mineralization (oxalic, acetic and formic acid) were followed and their formation from 4-chlorophenoxyacetic acid was confirmed. Dissolved oxygen was consumed to form reactive radicals during irradiation. Product analysis and confirmation are followed by gas chromatography/mass spectrometry and ion chromatography. The degradation path of 4-chlorophenoxyacetic acid was suggested with determined intermediates. PMID:26878254

  11. DEGRADATION OF THE CHLORINATED PHENOXYACETATE HERBICIDES 2,4-DICHLOROPHENOXYACETIC ACID AND 2,4,5- TRICHLOROPHENOXYACETIC BY PURE AND MIXED BACTERIAL CULTURES

    EPA Science Inventory

    Combined cell suspensions of the 2,4,5-trichlorophenoxyacetic acid (2,4,5-T)-metabolizing organism Pseudomonas cepacia AC1100, and the 2,4-dichlorophenoxyacetic acid (2,4-D)-metabolizing organism Alcaligenes eutrophus JMP134 were shown to effectively degrade either of these compo...

  12. Comparative toxicity of 20 herbicides to 5 periphytic algae and the relationship with mode of action.

    PubMed

    Nagai, Takashi; Taya, Kiyoshi; Yoda, Ikuko

    2016-02-01

    The authors used 5 species of periphytic algae to conduct toxicity assays of 20 herbicides. The 5 tested species represent riverine primary producers most likely to be affected by herbicides. A fluorescence microplate toxicity assay was used as an efficient and economical high-throughput assay. Toxicity characteristics were analyzed, focusing on their relationship to herbicide mode of action. The relative differences between 50% and 10% effect concentrations depended on herbicide mode of action, rather than tested species. Moreover, a clear relationship between sensitive species and herbicide mode of action was also observed. Green alga was most sensitive to herbicides of 2 mode of action groups: inhibitors of protoporphyrinogen oxidase and very long-chain fatty acid synthesis. Diatoms were most sensitive to herbicides of 1 mode of action group: 4-hydroxyphenyl-pyruvate-dioxygenase inhibitors. Cyanobacterium was most sensitive to herbicides of 1 mode of action group: inhibitors of acetolactate synthase. The species sensitivity distribution based on obtained data was also analyzed. The slopes of the species sensitivity distribution significantly differed among modes of action, suggesting that difference in species sensitivity is specific to the mode of action. In particular, differences in species sensitivity were markedly large for inhibitors of acetolactate synthase, protoporphyrinogen oxidase, and very long-chain fatty acid synthesis. The results clearly showed that a single algal species cannot represent the sensitivity of an algal assemblage. Therefore, multispecies algal toxicity data are essential for substances with specific modes of action. PMID:26174500

  13. Gene encoding herbicide safener binding protein

    SciTech Connect

    Walton, Jonathan D.; Scott-Craig, John S.

    1999-01-01

    The cDNA encoding safener binding protein (SafBP), also referred to as SBP1, is set forth in FIG. 5 and SEQ ID No. 1. The deduced amino acid sequence is provided in FIG. 5 and SEQ ID No. 2. Methods of making and using SBP1 and SafBP to alter a plant's sensitivity to certain herbicides or a plant's responsiveness to certain safeners are also provided, as well as expression vectors, transgenic plants or other organisms transfected with said vectors and seeds from said plants.

  14. Proximity to crops and residential to agricultural herbicides in Iowa

    USGS Publications Warehouse

    Ward, M.H.; Lubin, J.; Giglierano, J.; Colt, J.S.; Wolter, C.; Bekiroglu, N.; Camann, D.; Hartge, P.; Nuckols, J.R.

    2006-01-01

    Rural residents can be exposed to agricultural pesticides through the proximity of their homes to crop fields. Previously, we developed a method to create historical crop maps using a geographic information system. The aim of the present study was to determine whether crop maps are useful for predicting levels of crop herbicides in carpet dust samples from residences. From homes of participants in a case-control study of non-Hodgkin lymphoma in Iowa (1998-2000), we collected vacuum cleaner dust and measured 14 herbicides with high use on corn and soybeans in Iowa. Of 112 homes, 58% of residences had crops within 500 m of their home, an intermediate distance for primary drift from aerial and ground applications. Detection rates for herbicides ranged from 0% for metribuzin and cyanazine to 95% for 2,4-dichlorophenoxyacetic acid. Six herbicides used almost exclusively in agriculture were detected in 28% of homes. Detections and concentrations were highest in homes with an active farmer. Increasing acreage of corn and soybean fields within 750 m of homes was associated with significantly elevated odds of detecting agricultural herbicides compared with homes with no crops within 750 m (adjusted odds ratio per 10 acres = 1.06; 95% confidence interval, 1.02-1.11). Herbicide concentrations also increased significantly with increasing acreage within 750 m. We evaluated the distance of crop fields from the home at < 100, 101-250, 251-500, and 501-750 m. Including the crop buffer distance parameters in the model did not significantly improve the fit compared with a model with total acres within 750 m. Our results indicate that crop maps may be a useful method for estimating levels of herbicides in homes from nearby crop fields.

  15. Herbicides interfere with antigrazer defenses in Scenedesmus obliquus.

    PubMed

    Zhu, Xuexia; Sun, Yunfei; Zhang, Xingxing; Heng, Hailu; Nan, Haihong; Zhang, Lu; Huang, Yuan; Yang, Zhou

    2016-11-01

    The extensive application of herbicides has led to a serious threat of herbicide contamination to aquatic ecosystem. Herbicide exposure affects aquatic communities not only by exerting toxicity on single species but also by changing interspecific interactions. This study investigated the antigrazer defenses of the common green alga Scenedesmus obliquus against different herbicides [glyphosate, 2,4-dichlorophenoxyacetic acid (2,4-D), and atrazine] at various concentrations (0-2.0 mg L(-1)). In the presence of grazer (Daphnia)-derived cues, S. obliquus populations without herbicides formed high proportions of multicelled (e.g., four- and eight-celled) colonies. This result confirms that S. obliquus exhibits a morphological defense against grazing risk. At the low concentration range of 0.002-0.02 mg L(-1), the three herbicides exerted no influence on the growth and photosynthetic efficiency of S. obliquus, and multicelled colonies showed constant proportions. At the high concentration range of 0.20-2.0 mg L(-1), atrazine significantly inhibited the algal growth and photosynthesis whereas glyphosate or 2,4-D did not. Nonetheless, these levels of glyphosate or 2,4-D remarkably decreased the proportion of multicelled colonies, with reduced numbers of cells per particle in Daphnia filtrate-treated population. No eight-celled colony was formed after treatment with atrazine at 0.20-2.0 mg L(-1) despite the addition of Daphnia filtrate. These results suggest that herbicide exposure impairs antigrazer colonial morphs in phytoplankton although it is not sufficient to hamper algal growth. This phenomenon can increase the risk of predation by herbivores, thereby disrupting the inducible phytoplankton community. Furthermore, the predator-prey interactions between herbivores and phytoplankton can be potentially changed more seriously than previously considered. PMID:27501311

  16. Mode of Action Studies on Nitrodiphenyl Ether Herbicides

    PubMed Central

    Bowyer, John R.; Smith, Beverly J.; Camilleri, Patrick; Lee, Susan A.

    1987-01-01

    5-[2-Chloro-4-(trifluoromethyl)phenoxy]-2-nitroacetophenone oxime-o-(acetic acid, methyl ester) (DPEI), is a potent nitrodiphenyl ether herbicide which causes rapid leaf wilting, membrane lipid peroxidation, and chlorophyll destruction in a process which is both light- and O2-dependent. These effects resemble those of other nitrodiphenyl ether herbicides. Unlike paraquat, the herbicidal effects of DPEI are only slightly reduced by pretreatment with the photosynthetic electron transport inhibitor 3-(3,4-dichlorophenyl)-1,1-dimethylurea. DPEI is a weak inhibitor of photosynthetic electron transport (I50 15 micromolar for water to paraquat) in vitro, with at least one site of action at the cytochrome b6f complex. Ultrastructural studies and measurements of ethane formation resulting from lipid peroxidation indicate that mutants of barley lacking photosystem I (PSI) (viridis-zb63) or photosystem II (viridis-zd69) are resistant to paraquat but susceptible to DPEI. The results indicate that electron transfer through both photosystems is not essential for the toxic effects of nitrodiphenyl ether herbicides. Furthermore, the results show that neither cyclic electron transport around PSI, nor the diversion of electrons from PSI to O2 when NADPH consumption is blocked are essential for the phytotoxicity of nitrodiphenyl ether herbicides. Images Fig. 2 Fig. 3 Fig. 4 PMID:16665297

  17. Natural Compounds as Next-Generation Herbicides

    PubMed Central

    Dayan, Franck E.; Duke, Stephen O.

    2014-01-01

    Herbicides with new modes of action (MOAs) are badly needed due to the rapidly evolving resistance to commercial herbicides, but a new MOA has not been introduced in over 20 years. The greatest pest management challenge for organic agriculture is the lack of effective natural product herbicides. The structural diversity and evolved biological activity of natural phytotoxins offer opportunities for the development of both directly used natural compounds and synthetic herbicides with new target sites based on the structures of natural phytotoxins. Natural phytotoxins are also a source for the discovery of new herbicide target sites that can serve as the focus of traditional herbicide discovery efforts. There are many examples of strong natural phytotoxins with MOAs other than those used by commercial herbicides, which indicates that there are molecular targets of herbicides that can be added to the current repertoire of commercial herbicide MOAs. PMID:24784133

  18. Biological changes in the rhizosphere of wheat after foliar application of chlorocholinechloride, urea and 4-chloro-2-methylphenoxyacetic acid.

    PubMed

    Vraný, J

    1975-01-01

    In field experiments wheat in the phase of shooting was sprayed with solutions of chlorocholinechloride (CCC) and urea, CCC and ammonium salt MCPA (Aminex) or CCC, urea and Aminex. The effect of the treatment on dry weight of overground parts of wheat, number of bacteria, production of carbon dioxide, urease activity and content of ammonium in the rhizosphere soil was investigated. In all cases evolution of carbon dioxide in the rhizosphere soil was higher than that in the control soil. Highest numbers of bacteria were found in the rhizosphere soil of plants treated with urea, the herbicide and their mixtures. Content of ammonium was higher in the control soil than in the rhizosphere soils, the urease activity was highest in the rhizosphere soil of plants treated with the solution of the herbicide and with the combination of the herbicide with urea. PMID:1193493

  19. Molecular Bases for Sensitivity to Tubulin-Binding Herbicides in Green Foxtail[w

    PubMed Central

    Délye, Christophe; Menchari, Yosra; Michel, Séverine; Darmency, Henri

    2004-01-01

    We investigated the molecular bases for resistance to several classes of herbicides that bind tubulins in green foxtail (Setaria viridis L. Beauv.). We identified two α- and two β-tubulin genes in green foxtail. Sequence comparison between resistant and sensitive plants revealed two mutations, a leucine-to-phenylalanine change at position 136 and a threonine-to-isoleucine change at position 239, in the gene encoding α2-tubulin. Association of mutation at position 239 with herbicide resistance was demonstrated using near-isogenic lines derived from interspecific pairings between green foxtail and foxtail millet (Setaria italica L. Beauv.), and herbicide sensitivity bioassays combined with allele-specific PCR-mediated genotyping. Association of mutation at position 136 with herbicide resistance was demonstrated using herbicide sensitivity bioassays combined with allele-specific PCR-mediated genotyping. Both mutations were associated with recessive cross resistance to dinitroanilines and benzoic acids, no change in sensitivity to benzamides, and hypersensitivity to carbamates. Using three-dimensional modeling, we found that the two mutations are adjacent and located into a region involved in tubulin dimer-dimer contact. Comparison of three-dimensional α-tubulin models for organisms with contrasted sensitivity to tubulin-binding herbicides enabled us to propose that residue 253 and the vicinity of the side chain of residue 251 are critical determinants for the differences in herbicide sensitivity observed between organisms, and that positions 16, 24, 136, 239, 252, and 268 are involved in modulating sensitivity to these herbicides. PMID:15531712

  20. Review of literature on herbicides, including phenoxy herbicides and associated dioxins. Volume 13: Analysis of recent literature on health effects and Volume 14: Annotated bibliography of recent literature on health effects

    SciTech Connect

    Not Available

    1989-06-15

    The report consists of a bibliography and critical review of scientific literature that became available during 1988 on the health effects of the herbicides (including impurities) used as defoliants in the Vietnam conflict. An attempt has been made to identify all scientific literature (including unpublished reports) relevant to the potential human health effects of the herbicidal preparation commonly referred to as Agent Orange, the herbicidal active ingredients 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-trichloroacetic acid and their esters, as well as polychlorinated dibenzo-p-dioxin, henceforth referred to as TCDD, known to be contaminating impurities of some phenoxy herbicide preparations, an the herbicides, picloram and cacodylic acid. The scope of the review does not include literature dealing exclusively with the chemistry, analysis, or environmental fate and effects of these compounds.

  1. Herbicides and herbicide degradates in shallow groundwater and the Cedar River near a municipal well field, Cedar Rapids, Iowa

    USGS Publications Warehouse

    Boyd, R.A.

    2000-01-01

    Water samples were collected near a Cedar Rapids, Iowa municipal well field from June 1998 to August 1998 and analyzed for selected triazine and acetanilide herbicides and degradates. The purpose of the study was to evaluate the occurrence of herbicides and herbicide degradates in the well field during a period following springtime application of herbicides to upstream cropland. The well field is in an alluvial aquifer adjacent to the Cedar River. Parent herbicide concentrations generally were greatest in June, and decreased in July and August. Atrazine was most frequently detected and occurred at the greatest concentrations; acetochlor, cyanazine and metolachlor also were detected, but at lesser concentrations than atrazine. Triazine degradate concentrations were relatively small (<0.50 ??g/l) and generally decreased from June to August. Although the rate of groundwater movement is relatively fast (approx. 1 m per day) in the alluvial aquifer near the Cedar River, deethylatrazine (DEA) to atrazine ratios in groundwater samples collected near the Cedar River indicate that atrazine and DEA probably are gradually transported into the alluvial aquifer from the Cedar River. Deisopropylatrazine (DIA) to DEA ratios in water samples indicate most DIA in the Cedar River and alluvial aquifer is produced by atrazine degradation, although some could be from cyanazine degradation. Acetanilide degradates were detected more frequently and at greater concentrations than their corresponding parent herbicides. Ethanesulfonic-acid (ESA) degradates comprised at least 80% of the total acetanilide-degradate concentrations in samples collected from the Cedar River and alluvial aquifer in June, July and August; oxanilic acid degradates comprised less than 20% of the total concentrations. ESA-degradate concentrations generally were smallest in June and greater in July and August. Acetanilide degradate concentrations in groundwater adjacent to the Cedar River indicate acetanilide

  2. Evaluation of potential embryotoxicity and teratogenicity of 42 herbicides, insecticides, and petroleum contaminants to mallard eggs

    USGS Publications Warehouse

    Hoffman, D.J.; Albers, P.H.

    1984-01-01

    Results are reported for the embryotoxicity of 42 environmental contaminants applied externally to mallard (Anas platyrhynchos) eggs including crude and refined petroleum, and commercial formulations of herbicides and insecticides. Many of the petroleum pollutants were embryotoxic and moderately teratogenic and had LD50s of 0.3 to 5 ?l per egg (~6?90 ?g/g egg). The most toxic was a commercial oil used for control of road dust followed by South Louisiana crude oil, Kuwait crude, no. 2 fuel oil, bunker C fuel oil, and industrial and automotive waste oil. Prudhoe Bay crude, unused crankcase oil, aviation kerosene, and aliphatic hydrocarbon mixtures were less toxic ( LD50s of 18 to over 75 ? l) and less teratogenic. The LD50s of herbicides and insecticides in aqueous emulsion were measured by egg immersion; the most toxic were paraquat and trifluralin (LD50s of about 1.5 Ibs/A; 1.7 kg/ha). Propanil, bromoxynil with MCPA, methyl diclofop, prometon, endrin, sulprofos, and parathion were toxic (LD50s of 7 to 40 Ibs/A; 7.8?44.8 kg/ha), whereas 2,4-D, glyphosate, atrazine, carbaryl, dalapon, dicamba, methomyl, and phosmet were only slightly toxic or not toxic (LD50s of 178 to over 500 Ibs/A; 199?560 kg/ha). Pesticides in nontoxic oil vehicle applied by microliter pipet were up to 18 times more toxic than when applied in water vehicle, which was probably due to better penetration of the pesticide past the eggshell and its membranes. Teratogenic effects and impaired embryonic growth are reported and results discussed in terms of potential hazard at field levels of application. A discussion is provided on the effects of pollutants on the eggs of other species of birds under laboratory and field conditions.

  3. Glyphosate and dicamba herbicide tank mixture effects on native plant and non-genetically engineered soybean seedlings.

    PubMed

    Olszyk, David; Pfleeger, Thomas; Lee, E Henry; Plocher, Milton

    2015-07-01

    Crops engineered to contain genes for tolerance to multiple herbicides may be treated with several herbicides to manage weeds resistant to each herbicide. Thus, nearby non-target plants may be subjected to increased exposure to several herbicides used in combination. Of particular concern are native plants, as well as adjacent crops which have not been genetically engineered for tolerance to herbicides. We evaluated responses of seven species of native plants grown in a greenhouse and treated less than field application rates of glyphosate and/or dicamba: Andropogon gerardii, Asclepias syriaca, Eutrochium purpureum, Oenothera biennis, Polyganum lapathifolium, Solidago canadensis and Tridens flavus, and non-herbicide resistant soybean (Glycine max, Oregon line M4). Herbicide concentrations were 0.03 or 0.1 × field application rates of 1122 g ha(-1) active ingredient (a.i) (831 g ha(-1) acid glyphosate) for glyphosate and 562 g ha(-1) a.i. for dicamba. In general, plant growth responses to combinations of glyphosate and dicamba were less than the sum of growth responses to the individual herbicides (i.e., antagonistic effect), primarily when one or both herbicides alone caused a large reduction in growth. E. purpureum, P. lapathifolium and S. canadensis were the most sensitive species to both herbicides, while A. gerardii was the most tolerant, with no response to either herbicide. The combinations of herbicides resulted in responses most similar to that from dicamba alone for G. max and from glyphosate alone for T. flavus. The results of this study indicated the need for more data such as effects on native plants in the field to assess risks to non-target plants from combinations of herbicides. PMID:25821135

  4. Herbicide-Resistant: Toward an understanding of resistance development and the impact of herbicide resistant crops

    Technology Transfer Automated Retrieval System (TEKTRAN)

    For the past half century, herbicides have been the principal means of economic weed management in commercial crops in the US. Although weed resistance to herbicides was anticipated, weeds with resistance to herbicides did not appear until over 20 years after the initiation of herbicide use. Weed co...

  5. Spot Spraying Reduces Herbicide Concentrations in Runoff.

    PubMed

    Melland, Alice R; Silburn, D Mark; McHugh, Allen D; Fillols, Emilie; Rojas-Ponce, Samuel; Baillie, Craig; Lewis, Stephen

    2016-05-25

    Rainfall simulator trials were conducted on sugar cane paddocks across dry-tropical and subtropical Queensland, Australia, to examine the potential for spot spraying to reduce herbicide losses in runoff. Recommended rates of the herbicides glyphosate, 2,4-D, fluoroxypyr, atrazine, and diuron were sprayed onto 0, 20, 40, 50, 70, or 100% of the area of runoff plots. Simulated rainfall was applied 2 days after spraying to induce runoff at one plant cane and three ratoon crop sites. Over 50% of all herbicides were transported in the dissolved phase of runoff, regardless of the herbicide's sediment-water partition coefficient. For most sites and herbicides, runoff herbicide concentrations decreased with decreasing spray coverage and with decreasing herbicide load in the soil and cane residues. Importantly, sites with higher infiltration prior to runoff and lower total runoff had lower runoff herbicide concentrations. PMID:26479195

  6. Sarmentine, a natural herbicide from Piper species with multiple herbicide mechanisms of action.

    PubMed

    Dayan, Franck E; Owens, Daniel K; Watson, Susan B; Asolkar, Ratnakar N; Boddy, Louis G

    2015-01-01

    Sarmentine, 1-(1-pyrrolidinyl)-(2E,4E)-2,4-decadien-1-one, is a natural amide isolated from the fruits of Piper species. The compound has a number of interesting biological properties, including its broad-spectrum activity on weeds as a contact herbicide. Initial studies highlighted a similarity in response between plants treated with sarmentine and herbicidal soaps such as pelargonic acid (nonanoic acid). However, little was known about the mechanism of action leading to the rapid desiccation of foliage treated by sarmentine. In cucumber cotyledon disc-assays, sarmentine induced rapid light-independent loss of membrane integrity at 100 μM or higher concentration, whereas 3 mM pelargonic acid was required for a similar effect. Sarmentine was between 10 and 30 times more active than pelargonic acid on wild mustard, velvetleaf, redroot pigweed and crabgrass. Additionally, the potency of 30 μM sarmentine was greatly stimulated by light, suggesting that this natural product may also interfere with photosynthetic processes. This was confirmed by observing a complete inhibition of photosynthetic electron transport at that concentration. Sarmentine also acted as an inhibitor of photosystem II (PSII) on isolated thylakoid membranes by competing for the binding site of plastoquinone. This can be attributed in part to structural similarities between herbicides like sarmentine and diuron. While this mechanism of action accounts for the light stimulation of the activity of sarmentine, it does not account for its ability to destabilize membranes in darkness. In this respect, sarmentine has some structural similarity to crotonoyl-CoA, the substrate of enoyl-ACP reductase, a key enzyme in the early steps of fatty acid synthesis. Inhibitors of this enzyme, such as triclosan, cause rapid loss of membrane integrity in the dark. Sarmentine inhibited the activity of enoyl-ACP reductase, with an I 50app of 18.3 μM. Therefore, the herbicidal activity of sarmentine appears to be a

  7. Sarmentine, a natural herbicide from Piper species with multiple herbicide mechanisms of action

    PubMed Central

    Dayan, Franck E.; Owens, Daniel K.; Watson, Susan B.; Asolkar, Ratnakar N.; Boddy, Louis G.

    2015-01-01

    Sarmentine, 1-(1-pyrrolidinyl)-(2E,4E)-2,4-decadien-1-one, is a natural amide isolated from the fruits of Piper species. The compound has a number of interesting biological properties, including its broad-spectrum activity on weeds as a contact herbicide. Initial studies highlighted a similarity in response between plants treated with sarmentine and herbicidal soaps such as pelargonic acid (nonanoic acid). However, little was known about the mechanism of action leading to the rapid desiccation of foliage treated by sarmentine. In cucumber cotyledon disc-assays, sarmentine induced rapid light-independent loss of membrane integrity at 100 μM or higher concentration, whereas 3 mM pelargonic acid was required for a similar effect. Sarmentine was between 10 and 30 times more active than pelargonic acid on wild mustard, velvetleaf, redroot pigweed and crabgrass. Additionally, the potency of 30 μM sarmentine was greatly stimulated by light, suggesting that this natural product may also interfere with photosynthetic processes. This was confirmed by observing a complete inhibition of photosynthetic electron transport at that concentration. Sarmentine also acted as an inhibitor of photosystem II (PSII) on isolated thylakoid membranes by competing for the binding site of plastoquinone. This can be attributed in part to structural similarities between herbicides like sarmentine and diuron. While this mechanism of action accounts for the light stimulation of the activity of sarmentine, it does not account for its ability to destabilize membranes in darkness. In this respect, sarmentine has some structural similarity to crotonoyl-CoA, the substrate of enoyl-ACP reductase, a key enzyme in the early steps of fatty acid synthesis. Inhibitors of this enzyme, such as triclosan, cause rapid loss of membrane integrity in the dark. Sarmentine inhibited the activity of enoyl-ACP reductase, with an I50app of 18.3 μM. Therefore, the herbicidal activity of sarmentine appears to be a

  8. Transformation of herbicides under transient anoxia

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Resurgence in the use of soil-applied residual herbicides to augment performance of failing post-emergence herbicides has predictably reignited concerns over potential offsite movement, carryover damage onsite, or potential herbicide failure due to accelerated degradation. Many of the key processes ...

  9. Irrigation affects herbicide penetration of shrub canopies

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nursery growers can apply herbicides in either granular or sprayed formulations. Despite greater risk for injury, sprayed preemergence herbicides are often less expensive than an equivalent granular formulation, easier to apply, and result in more uniform application. When herbicides are sprayed o...

  10. Best management practices for herbicide resistance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In spite of the recent focus on herbicide resistant weeds, herbicide resistant weeds are not new to agriculture; the first herbicide resistant weed was documented in 1957, with the first widespread resistance occurring in common groundsel with atrazine in the early 1970’s. Glyphosate resistant weed...

  11. Comparisons of herbicide treated and cultivated herbicide-resistant corn

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Four glyphosate resistant corn (Zea mays L.) hybrids, a glufosinate-ammonium resistant hybrid, and a conventional atrazine resistant hybrid grown at Stoneville, MS in 2005, 2006, and 2007 with furrow irrigation were treated with thier respective herbicides and their growth, yeild, and mycotoxin inci...

  12. Interactions of Synthetic Herbicides with Plant Disease and Microbial Herbicides

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Synthetic herbicides have the potential to influence plant disease by several mechanisms. They can enhance disease or protect plants from pathogens due to direct effects on the microbe, to effects on the plant, or to effects on both organisms. The particular effect is a function of many factors in...

  13. Analysis of selected herbicide metabolites in surface and ground water of the United States

    USGS Publications Warehouse

    Scribner, E.A.; Thurman, E.M.; Zimmerman, L.R.

    2000-01-01

    One of the primary goals of the US Geological Survey (USGS) Laboratory in Lawrence, Kansas, is to develop analytical methods for the analysis of herbicide metabolites in surface and ground water that are vital to the study of herbicide fate and degradation pathways in the environment. Methods to measure metabolite concentrations from three major classes of herbicides - triazine, chloroacetanilide and phenyl-urea - have been developed. Methods for triazine metabolite detection cover nine compounds: six compounds are detected by gas chromatography/mass spectrometry; one is detected by high-performance liquid chromatography with diode-array detection; and eight are detected by liquid chromatography/mass spectrometry. Two metabolites of the chloroacetanilide herbicides - ethane sulfonic acid and oxanilic acid - are detected by high-performance liquid chromatography with diode-array detection and liquid chromatography/mass spectrometry. Alachlor ethane sulfonic acid also has been detected by solid-phase extraction and enzyme-linked immunosorbent assay. Six phenylurea metabolites are all detected by liquid chromatography/mass spectrometry; four of the six metabolites also are detected by gas chromatography/mass spectrometry. Additionally, surveys of herbicides and their metabolites in surface water, ground water, lakes, reservoirs, and rainfall have been conducted through the USGS laboratory in Lawrence. These surveys have been useful in determining herbicide and metabolite occurrence and temporal distribution and have shown that metabolites may be useful in evaluation of non-point-source contamination. Copyright (C) 2000 Elsevier Science B.V.

  14. Herbicide poisoning: A diagnostic challenge

    PubMed Central

    Ghosh, Supradip; Singh, Amandeep; Dewan, Himanshu; Walia, Gunwant; Bansal, Abhishek

    2012-01-01

    Despite widespread availability, reports of herbicide poisoning from India are not common. Diagnosis is often difficult in the absence of proper history, non-specific clinical features and lack of diagnostic tests. A case of Paraquat poisoning is reported where diagnosis could be established only after the recovery of the patient. The literature is reviewed. PMID:22557836

  15. Introduction to Weeds and Herbicides.

    ERIC Educational Resources Information Center

    Hartwig, Nathan L.

    This agriculture extension service publication from Pennsylvania State University is an introduction to weed control and herbicide use. An initial discussion of the characteristics of weeds includes scientific naming, weed competition with crops, weed dispersal and dormancy, and conditions affecting weed seed germination. The main body of the…

  16. Herbicides as ripeners for sugarcane

    Technology Transfer Automated Retrieval System (TEKTRAN)

    At the start of the sugarcane harvest season in Louisiana, late-September or early-October, sucrose content in sugarcane is relatively low compared to late in the harvest season. In order for early-harvested sugarcane to be profitable, chemicals, primarily herbicides, have been evaluated for their e...

  17. Up and coming organic herbicides

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In a recent national survey, weed control research was designated as the top research priority by organic producers. Organic weed control methods include crop rotations, cover crops, planting systems, mulches, mechanical methods, flaming, and organic herbicides. Although mechanical weed control th...

  18. Herbicide Effects on Plant Disease

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The effect of herbicides on plant disease is an important, but generally overlooked, aspect of integrated pest management. Furthermore, these interactions can be crucial contributors to the success or failure of the biocontrol of weeds with microbes. Indirectly, through their strong effects on pla...

  19. Transgenic Crops for Herbicide Resistance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Since their introduction in 1995, crops made resistant to the broad-spectrum herbicides glyphosate and glufosinate with transgenes are widely available and used in much of the world. As of 2008, over 80% of the transgenic crops grown world-wide have this transgenic trait. This technology has had m...

  20. Biotechnology: herbicide-resistant crops

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Transgenic, herbicide-resistant (HR) crops are planted on about 80% of the land covered by transgenic crops. More than 90% of HR crios are glyphosate-resistant (GR) crops, the others being resistant to glufosinate. The wide-scale adoption of HR crops, largely for economic reasons, has been the mos...

  1. Growth Inhibition of Pathogenic Bacteria by Sulfonylurea Herbicides

    PubMed Central

    Kreisberg, Jason F.; Ong, Nicholas T.; Krishna, Aishwarya; Joseph, Thomas L.; Wang, Jing; Ong, Catherine; Ooi, Hui Ann; Sung, Julie C.; Siew, Chern Chiang; Chang, Grace C.; Biot, Fabrice; Cuccui, Jon; Wren, Brendan W.; Chan, Joey; Sivalingam, Suppiah P.; Zhang, Lian-Hui; Verma, Chandra

    2013-01-01

    Emerging resistance to current antibiotics raises the need for new microbial drug targets. We show that targeting branched-chain amino acid (BCAA) biosynthesis using sulfonylurea herbicides, which inhibit the BCAA biosynthetic enzyme acetohydroxyacid synthase (AHAS), can exert bacteriostatic effects on several pathogenic bacteria, including Burkholderia pseudomallei, Pseudomonas aeruginosa, and Acinetobacter baumannii. Our results suggest that targeting biosynthetic enzymes like AHAS, which are lacking in humans, could represent a promising antimicrobial drug strategy. PMID:23263008

  2. Herbicidal and Cytotoxic Constituents from Aralia armata (Wall.) Seem.

    PubMed

    Miao, Hui; Sun, Yongyan; Yuan, Yunfei; Zhao, Huanhuan; Wu, Jiao; Zhang, Weiyun; Zhou, Lijuan

    2016-04-01

    Two new triterpenoids, 3β-hydroxyoleana-11,13(18)-diene-28,30-dioic acid (1) and 3-oxooleana-11,13(18)-diene-28,30-dioic acid (2), one novel triterpenoid glycoside, 3β-O-(6'-O-methyl-β-d-glucuronopyranosyl)oleana-11,13(18)-dien-28-oic acid (3) along with six known compounds (4 - 9) were isolated from the stem bark of Aralia armata (Wall.) Seem. Their structures were elucidated through extensive spectroscopic methods. The herbicidal activities of these compounds against Bidens pilosa L., an invasive weed in P. R. China, were evaluated. Compounds 3, 5, and 6 exhibited more significant herbicidal activities on B. pilosa than the positive-control pendimethalin. Their possible use as herbicidal chemicals or model compounds deserved more attention. The effects of compounds 1 - 9 on Spodoptera litura cultured cell line Sl-1 cell proliferation and its morphology were also evaluated. The results indicated that compounds 1 - 5 affected Sl-1 cell proliferation. Compound 3 showed more obvious proliferation inhibition activities on Sl-1 cell than the positive-control rotenone. With regard to the effect on morphology, compound 2 significantly changed Sl-1 cell, resulting in cell blebbing and vacuole forming. Triterpenoids aremedicinally and agriculturally important, and cytotoxicity of the three new compounds 1 - 3 deserved further studies. PMID:26948515

  3. Herbicides for Calendula

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The rising need for replacements for volatile organic compounds (VOC), which are used in the manufacture of paints, plastics, pesticides, etc., has placed demands on drying oils that may not be met by current sources. The primary source is eleostearic acid, or tung oil, which is derived from the see...

  4. Herbicides in streams. Midwestern United States

    USGS Publications Warehouse

    Goolsby, Donald A.; Thurman, E. Michael; Kolpin, Dana W.

    1991-01-01

    Results from a 2-year study of 149 streams geographically distributed across the corn-producing region of 10 midwestern States show that detectable concentrations of herbicides persist year round in most streams. Some herbicides exceeded proposed maximum contaminant levels for drinking water for periods of several weeks to several months following application. Atrazine was the most frequently detected and most persistent herbicide measured, followed by desethylatrazine and metolachlor. The seasonal distribution of atrazine indicates that aquifers contributing base flow to many of the streams are contaminated with herbicides.

  5. Hydrothermal electrocatalytic oxidation for the treatment of herbicides wastewater.

    PubMed

    Xiao, Hanshuang; Lv, Baoying; Gao, Junxia; Zhao, Guohua

    2016-05-01

    A hydrothermal electrocatalytic oxidation (HTECO) method is adopted to treat the biorefractory and toxic 2,4-dichlorophenoxyacetic acid (2,4-D) herbicides wastewater on nano-Pt/Ti electrode in the existence of H2O2. Comparisons for the removal of 2,4-D and total organic carbon (TOC) have been carried out between HTECO with individual electrochemical oxidation (EO) and hydrothermal catalytic oxidation (HTCO), showing that high mineralization efficiency was obtained in HTECO process. The possible factors resulting in the high removal efficiency in HTECO process have been studied by investigating the properties of the electrode and solution in hydrothermal condition, the amount of active radicals, the decay kinetic, and evolution of main intermediates of 2,4-D. Thus, an enhanced mechanism for HTECO method for the treatment of herbicides wastewater has been obtained. PMID:26865489

  6. SEASONAL EFFECTS ON MICROBIAL TRANSFORMATION RATES OF AN HERBICIDE IN A FRESHWATER STREAM: APPLICATION OF LABORATORY DATA TO A FIELD SITE

    EPA Science Inventory

    Seasonal effects on microbial transformation rates of an herbicide, 2,4-dichlorophenoxyacetic acid butoxyethyl ester (2,4-DBE), in a freshwater stream were investigated using low concentrations (less than 100 micrograms L(-1)) of the herbicide mixed with an inert dye, rhodamine W...

  7. Uptake and Accumulation of the Herbicides Chlorsulfuron and Clopyralid in Excised Pea Root Tissue 1

    PubMed Central

    Devine, Malcolm D.; Bestman, Hank D.; Vanden Born, William H.

    1987-01-01

    The herbicides chlorsulfuron and clopyralid were taken up rapidly by excised pea root tissue and accumulated in the tissue to concentrations ten and four times those in the external medium, respectively. Uptake was related linearly to external herbicide concentration over a wide concentration range, implying that transport across the membrane is by nonfacilitated diffusion. Uptake of both compounds was influenced by pH, with greatest uptake at low pH. The pH dependence of uptake suggests that the herbicides (both of which are weak acids) are transported across the plasma membrane in the undissociated form, and accumulate in the cytoplasm by an ion trap mechanism. Most of the absorbed herbicide effluxed from the tissue when it was transferred to herbicide-free buffer, indicating that the accumulation was not due to irreversible binding. Consequently, both herbicides remain available for transfer to the phloem. These results can explain the high reported phloem mobility of clopyralid in intact plants. The low phloem mobility of chlorsulfuron must be accounted for by factors that override its ability to accumulate in the symplast. PMID:16665689

  8. Enzyme activity and microorganisms diversity in soil contaminated with the Boreal 58 WG herbicide.

    PubMed

    Kucharski, Jan; Tomkiel, Monika; Baćmaga, Małgorzata; Borowik, Agata; Wyszkowska, Jadwiga

    2016-07-01

    Next-generation herbicides are relatively safe when used properly, but the recommended rates are relatively low, which can lead to overdosing. This study evaluated the responses of soil-dwelling microorganisms and soil enzymes to contamination with the Boreal 58 WG herbicide. The analyzed product contains active ingredients flufenacet and isoxaflutole. All tests were performed under laboratory conditions. The analyzed material was sandy clay. Boreal 58 WG was introduced to soil in four doses. Soil without the addition of the herbicide served as the control. The soil was mixed with the tested herbicide, and its moisture content was maintained at 50% of capillary water capacity. Biochemical and microbiological analyses were performed on experimental days 0, 20, 40, 80 and 160. Accidental contamination of soil with the Boreal 58 WG herbicide led to a relatively minor imbalance in the soil microbiological and biochemical profile. The herbicide dose influenced dehydrogenase activity in only 0.84%, urease activity in 2.04%, β-glucosidase activity in 8.26%, catalase activity in 12.40%, arylsulfatase activity in 12.54%, acid phosphatase activity in 42.11%, numbers of organotrophic bacteria in 18.29%, actinomyces counts in 1.31% and fungi counts in 6.86%. PMID:27050595

  9. The impact of altered herbicide residues in transgenic herbicide-resistant crops on standard setting for herbicide residues.

    PubMed

    Kleter, Gijs A; Unsworth, John B; Harris, Caroline A

    2011-10-01

    The global area covered with transgenic (genetically modified) crops has rapidly increased since their introduction in the mid-1990s. Most of these crops have been rendered herbicide resistant, for which it can be envisaged that the modification has an impact on the profile and level of herbicide residues within these crops. In this article, the four main categories of herbicide resistance, including resistance to acetolactate-synthase inhibitors, bromoxynil, glufosinate and glyphosate, are reviewed. The topics considered are the molecular mechanism underlying the herbicide resistance, the nature and levels of the residues formed and their impact on the residue definition and maximum residue limits (MRLs) defined by the Codex Alimentarius Commission and national authorities. No general conclusions can be drawn concerning the nature and level of residues, which has to be done on a case-by-case basis. International residue definitions and MRLs are still lacking for some herbicide-crop combinations, and harmonisation is therefore recommended. PMID:21898904

  10. Bacterial degradation of phenoxy herbicide mixtures 2,4-D and MCPP

    SciTech Connect

    Kyeheon Oh; Tuovinen, O.H. )

    1991-08-01

    The phenoxy herbicides 2,4-dichlorophenoxyacetic acid (2,4-D) and 2-(2-methyl-4-chlorophenoxy)propionic acid (MCPP) have auxin-like growth regulating properties and are extensively used for the control of broad-leaf angiosperm weeds. The microbiological degradation of 2,4-D by pure and mixed cultures has been examined in a number of studies. The authors have previously evaluated the concurrent microbiological degradation of 2,4-D and MCPP in stirred tank reactors. For the present paper, they examined the utilization of the two substrates by three mixed cultures that had a previous history of growth with the respective single phenoxy herbicide.

  11. Control of Butterfly Bush with Postemergence Herbicides

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Butterfly bush (Buddleja davidii) is classified as invasive in several parts of the United States. Two experiments were conducted to evaluate the effectiveness of four herbicides and two application methods on postemergence butterfly bush control. The four herbicides included: Roundup (glyphosate)...

  12. Tillage and Herbicide Influence on Pigweed Management

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cotton producers have struggled with broadleaf weed control for many years. Historically, postemergence-directed herbicides required a height differential provided using a preemergence or preplant-incorporated herbicide to suppress weed growth during the first few weeks following planting. However,...

  13. Post-emergence herbicides useful in calendula

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Easy and effective weed control is required by growers who are considering new industrial crops. Post-emergence herbicides typically are the products of choice by today’s growers. Unfortunately, post-emergence herbicides with proven safety margins are not known for calendula (Calendula officinalis),...

  14. Managing the evolution of herbicide resistance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Herbicide-resistant (HR) weeds are widespread threats to the sustainability, productivity, and profitability of many cropping systems. Efforts to combat their spread through herbicide rotation schedules have been marginally effective at best. Despite the scope of the problem, we lack sound empirical...

  15. Herbicide residues in grapes and wine.

    PubMed

    Ying, G G; Williams, B

    1999-05-01

    The persistence of several common herbicides from grapes to wine has been studied. Shiraz, Tarrango and Doradillo grapes were separately sprayed with either norflurazon, oxyfluorfen, oxadiazon or trifluralin-persistent herbicides commonly used for weed control in vineyards. The dissipation of the herbicides from the grapes was followed for 28 days following treatment. Results showed that norflurazon was the most persist herbicide although there were detectable residues of all the herbicides on both red and white grapes at the end of the study period. The penetration of herbicides into the flesh of the grapes was found to be significantly greater for white grapes than for red grapes. Small-lot winemaking experiments showed that norflurazon persisted at levels close to the initial concentration through vinification and into the finished wine. The other herbicides degraded, essentially via first-order kinetics, within the period of "first fermentation" and had largely disappeared after 28 days. The use of charcoal together with filter pads, or with diatomaceous earth was shown to be very effective in removing herbicide residues from the wine. A 5% charcoal filter removed more than 96% of the norflurazon persisting in the treated wine. PMID:10227191

  16. Glyphosate: A Once in a Century Herbicide

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Since its commercial introduction in 1974, glyphosate (N-phosphonomethyl glycine) has become the dominant herbicide worldwide. There are several reasons for its success. Glyphosate is a highly effective broad spectrum herbicide, yet it is very toxicologically and environmentally safe. Glyphosate ...

  17. Quantification of the new triketone herbicides, sulcotrione and mesotrione, and other important herbicides and metabolites, at the ng/l level in surface waters using liquid chromatography-tandem mass spectrometry.

    PubMed

    Freitas, Luciana Gomides; Götz, Christian W; Ruff, Matthias; Singer, Heinz P; Müller, Stephan R

    2004-03-01

    The LC/ESI/MSMS method allows the trace quantification (ng/l) of the new triketone herbicides, i.e. sulcotrione and mesotrione, and important herbicides and metabolites, in natural waters. Solid phase extraction (SPE) for sample enrichment is performed with OASIS (recoveries 94-112% for parent herbicides). Neutral and acidic compounds were analyzed separately with ESI in positive and negative mode, respectively. Quantification limits varied between 0.5 and 10 ng/l. The acidic herbicides detection was improved by a neutralizing post-column addition solution. The influence of ion suppression on quantification is discussed in detail. It is shown that we could overcome this problem and achieve reliable quantification using isotope labeled internal standards (ILIS) for every single analyte. The methods performance is illustrated with samples from a lake depth profile. PMID:14989481

  18. Precision Herbicide Application Technologies To Decrease Herbicide Losses in Furrow Irrigation Outflows in a Northeastern Australian Cropping System.

    PubMed

    Davis, Aaron M; Pradolin, Jordan

    2016-05-25

    This study compared water quality benefits of using precision herbicide application technologies in relation to traditional spraying approaches across several pre- and postemergent herbicides in furrow-irrigated canefarming systems. The use of shielded sprayers (herbicide banding) provided herbicide load reductions extending substantially beyond simple proportionate decreases in amount of active herbicide ingredient applied to paddocks. These reductions were due largely to the extra management control available to irrigating growers in relation to where both herbicides and irrigation water can be applied to paddocks, coupled with knowledge of herbicide toxicological and physicochemical properties. Despite more complex herbicide mixtures being applied in banded practices, banding provided capacity for greatly reduced environmental toxicity in off-paddock losses. Similar toxicological and loss profiles of alternative herbicides relative to recently regulated pre-emergent herbicides highlight the need for a carefully considered approach to integrating alternative herbicides into improved pest management. PMID:26795709

  19. Going natural: Effective weed control in squash with pelargonic acid

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pelargonic acid, a natural, but not certified organic herbicide, has been shown to be phytotoxic, acting as a contact herbicide, injuring and killing plants through cell membrane disruption. Pelargonic acid, a fatty acid also known as nonanoic acid, is a nine-carbon chained organic compound found in...

  20. Modified cellulose synthase gene from 'Arabidopsis thaliana' confers herbicide resistance to plants

    SciTech Connect

    Somerville, Chris R.; Scieble, Wolf

    2000-10-11

    Cellulose synthase ('CS'), a key enzyme in the biosynthesis of cellulose in plants is inhibited by herbicides comprising thiazolidinones such as 5-tert-butyl-carbamoyloxy-3-(3-trifluromethyl) phenyl-4-thiazolidinone (TZ), isoxaben and 2,6-dichlorobenzonitrile (DCB). Two mutant genes encoding isoxaben and TZ-resistant cellulose synthase have been isolated from isoxaben and TZ-resistant Arabidopsis thaliana mutants. When compared with the gene coding for isoxaben or TZ-sensitive cellulose synthase, one of the resistant CS genes contains a point mutation, wherein glycine residue 998 is replaced by an aspartic acid. The other resistant mutation is due to a threonine to isoleucine change at amino acid residue 942. The mutant CS gene can be used to impart herbicide resistance to a plant; thereby permitting the utilization of the herbicide as a single application at a concentration which ensures the complete or substantially complete killing of weeds, while leaving the transgenic crop plant essentially undamaged.

  1. Tandem mass spectrometry of herbicide residues in lipid-rich tissue.

    PubMed

    Headley, J V; Peru, K M; Arts, M T

    1995-12-01

    A tandem mass spectrometry procedure, originally developed for bacterial biofilms was adapted for the identification of herbicide residues in lipid-rich tissue of amphipods collected from microcosms in a prairie wetland. For this application, the amounts of tissue employed (less than 1 mg wet weight), and detection of target analytes at picogram levels, were similar to the values reported for bacterial biofilms. Described is an application of the technique for the identification of residues of the herbicide S-2,3,3-trichloroallyl diisopropyl thiocarbamate (triallate; trade name Avadex-BW). For amphipods collected from microcosms exposed to the herbicide 2-[4-(2,4-dichlorophenoxy)phenoxy]propionic acid methyl ester (diclofop-methyl, trade name Hoe Grass), there were detectable levels of only the hydrolysis product, diclofop acid, in the lipid-rich tissue. Other transformation products reported for bacterial biofilms were not observed in the amphipods. PMID:8633778

  2. Modified cellulose synthase gene from Arabidopsis thaliana confers herbicide resistance to plants

    DOEpatents

    Somerville, Chris R.; Scheible, Wolf

    2007-07-10

    Cellulose synthase ("CS"), a key enzyme in the biosynthesis of cellulose in plants is inhibited by herbicides comprising thiazolidinones such as 5-tert-butyl-carbamoyloxy-3-(3-trifluromethyl)phenyl-4-thiazolidinone (TZ), isoxaben and 2,6-dichlorobenzonitrile (DCB). Two mutant genes encoding isoxaben and TZ-resistant cellulose synthase have been isolated from isoxaben and TZ-resistant Arabidopsis thaliana mutants. When compared with the gene coding for isoxaben or TZ-sensitive cellulose synthase, one of the resistant CS genes contains a point mutation, wherein glycine residue 998 is replaced by an aspartic acid. The other resistant mutation is due to a threonine to isoleucine change at amino acid residue 942. The mutant CS gene can be used to impart herbicide resistance to a plant; thereby permitting the utilization of the herbicide as a single application at a concentration which ensures the complete or substantially complete killing of weeds, while leaving the transgenic crop plant essentially undamaged.

  3. Physiological Basis for Differential Sensitivities of Plant Species to Protoporphyrinogen Oxidase-Inhibiting Herbicides 1

    PubMed Central

    Sherman, Timothy D.; Becerril, José M.; Matsumoto, Hiroshi; Duke, Mary V.; Jacobs, Judy M.; Jacobs, Nicholas J.; Duke, Stephen O.

    1991-01-01

    With a leaf disc assay, 11 species were tested for effects of the herbicide acifluorfen on porphyrin accumulation in darkness and subsequent electrolyte leakage and photobleaching of chlorophyll after exposure to light. Protoporphyrin IX (Proto IX) was the only porphyrin that was substantially increased by the herbicide in any of the species. However, there was a wide range in the amount of Proto IX accumulation caused by 0.1 millimolar acifluorfen between species. Within species, there was a reduced effect of the herbicide in older tissues. Therefore, direct quantitative comparisons between species are difficult. Nevertheless, when data from different species and from tissues of different age within a species were plotted, there was a curvilinear relationship between the amount of Proto IX caused to accumulate during 20 hours of darkness and the amount of electrolyte leakage or chlorophyll photobleaching caused after 6 and 24 hours of light, respectively, following the dark period. Herbicidal damage plateaued at about 10 nanomoles of Proto IX per gram of fresh weight. Little difference was found between in vitro acifluorfen inhibition of protoporphyrinogen oxidase (Protox) of plastid preparations of mustard, cucumber, and morning glory, three species with large differences in their susceptibility at the tissue level. Mustard, a highly tolerant species, produced little Proto IX in response to the herbicide, despite having a highly susceptible Protox. Acifluorfen blocked carbon flow from δ-aminolevulinic acid to protochlorophyllide in mustard, indicating that it inhibits Protox in vivo. Increasing δ-aminolevulinic acid concentrations (33-333 micromolar) supplied to mustard with 0.1 millimolar acifluorfen increased Proto IX accumulation and herbicidal activity, demonstrating that mustard sensitivity to Proto IX was similar to other species. Differential susceptibility to acifluorfen of the species examined in this study appears to be due in large part to

  4. Mitigation of plant penetration into radioactive waste utilizing herbicides

    SciTech Connect

    Cox, G.R.

    1982-01-01

    This paper describes the use of herbicides as an effective method of precluding plant root penetration into buried radioactive wastes. The discussed surface applications are selective herbicides to control broadleaf vegetation in grasses; nonselective herbicides, which control all vegetation; and slow-release forms of these herbicides to prolong effectiveness.

  5. Acetamide herbicides and their degradation products in ground water and surface water of the United States, 1993-2003

    USGS Publications Warehouse

    Scribner, Elisabeth A.; Dietze, Julie E.; Thurman, Michael

    2004-01-01

    During 1993 through 2003, the U.S. Geological Survey conducted a number of studies to investigate and document the occurrence, fate, and transport of acetamide herbicides and their degradation products in ground and surface water. As part of these studies, approximately 5,100 water samples were collected and analyzed for the acetamide parent herbicides acetochlor, alachlor, dimethenamid, flufenacet, and metolachlor and their degradation products ethanesulfonic acid, oxanilic acid, and sulfinyl acetic acid. During this period, various analytical methods were developed to detect and measure concentrations of acetamide herbicides and their degradation products in ground water and surface water. Results showed that the degradation products of acetamide herbicides in ground water were detected more frequently and occurred at higher concentrations than their parent compounds. Further study showed that the acetamide herbicides and their degradation products were detected more frequently in surface water than in ground water. In general, the parent compounds were detected at similar or greater frequencies than the degradation products in surface water. The developed methods and data were valuable for acquiring information about the occurrence, fate, and transport of the herbicides and their degradation products and the importance of analyzing for both parent compounds and their degradate products in water-quality studies.

  6. Influence of frozen storage on herbicide degradation capacity in surface and subsurface sandy soils.

    PubMed

    Mortensen, Sarah K; Jacobsen, Carsten S

    2004-12-15

    The degradation of MCPA and metribuzin was investigated in laboratory batch experiments using fresh and frozen-stored soil samples from the unsaturated zone of a sandy soil. Mineralization potentials measured in fresh and frozen-stored soils were similar, and mineralization kinetics in surface and subsurface soils could be fitted using the same kinetic models. MCPA mineralization data from all three horizons were best described with the exponential growth form of the three-half-order model. During the mineralization of MCPA, growth in MCPA-degrading microbial populations was confirmed by increases in the abundance of tfdA genes following MCPA exposure. In contrast to MCPA, metribuzin mineralization followed zero-order kinetics, and very little metribuzin was mineralized (<1%) in all three of the investigated soil horizons. In addition, metribuzin dissipation and metabolite formation were also measured in surface and subsurface soils using LC-MS/MS. Differences in metribuzin dissipation were observed in the A-horizon at the beginning of the experiment and resulted in substantially different 50% disappearance time, DT50, values for frozen-stored (36 days) and fresh (<15 days) soil samples. However, the % of metribuzin remaining in fresh and frozen-stored surface soils was comparable from day 37 and thereafter. PMID:15669321

  7. Proteomics and redox-proteomics of the effects of herbicides on a wild-type wine Saccharomyces cerevisiae strain.

    PubMed

    Braconi, Daniela; Bernardini, Giulia; Possenti, Silvia; Laschi, Marcella; Arena, Simona; Scaloni, Andrea; Geminiani, Michela; Sotgiu, Michele; Santucci, Annalisa

    2009-01-01

    Several toxicological and environmental problems are associated with the extensive use of agricultural pesticides, such as herbicides. Nevertheless, little is known about the toxic effects of formulated herbicides, since many studies have been carried out using pure active molecules alone. In this work, we used as an eukaryotic model system an autochthonous wine yeast strain to investigate the effects of three commercial herbicides, currently used in the same geographical area from where this strain had been isolated. We carried out a comparative proteomic analysis to study the effects at the protein level of the herbicide-related stress, and found that the herbicides tested can alter the yeast proteome producing responses that share homologies with those observed treating yeast cells with the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) or with well-known oxidizing agents. We evaluated, through redox-proteomic techniques, protein carbonylation as a biomarker of oxidative stress. This analysis showed that herbicide-induced carbonylation is a dynamic phenomenon with degrees of selectivity. PMID:19032026

  8. Global perspective of herbicide-resistant weeds.

    PubMed

    Heap, Ian

    2014-09-01

    Two hundred and twenty weed species have evolved resistance to one or more herbicides, and there are now 404 unique cases (species × site of action) of herbicide-resistant weeds globally. ALS inhibitor-resistant weeds account for about a third of all cases (133/404) and are particularly troublesome in rice and cereals. Although 71 weed species have been identified with triazine resistance, their importance has dwindled with the shift towards Roundup Ready® crops in the USA and the reduction of triazine usage in Europe. Forty-three grasses have evolved resistance to ACCase inhibitors, with the most serious cases being Avena spp., Lolium spp., Phalaris spp., Setaria spp. and Alopecurus myosuroides, infesting more than 25 million hectares of cereal production globally. Of the 24 weed species with glyphosate resistance, 16 have been found in Roundup Ready® cropping systems. Although Conyza canadensis is the most widespread glyphosate-resistant weed, Amaranthus palmeri and Amaranthus tuberculartus are the two most economically important glyphosate-resistant weeds because of the area they infest and the fact that these species have evolved resistance to numerous other herbicide sites of action, leaving growers with few herbicidal options for their control. The agricultural chemical industry has not brought any new herbicides with novel sites of action to market in over 30 years, making growers reliant on using existing herbicides in new ways. In addition, tougher registration and environmental regulations on herbicides have resulted in a loss of some herbicides, particularly in Europe. The lack of novel herbicide chemistries being brought to market combined with the rapid increase in multiple resistance in weeds threatens crop production worldwide. PMID:24302673

  9. Hybridization using cytoplasmic male sterility, cytoplasmic herbicide tolerance, and herbicide tolerance from nuclear genes

    SciTech Connect

    Beversdorf, W.D.; Erickson, L.R.; Grant, I.

    1987-04-14

    An improved process is described for producing a substantially homogeneous population of plants of a predetermined hybrid variety of crop which is capable of undergoing self-pollination and cross-pollination. The process comprises: growing in a first planting area a substantially random population of cytoplasmic male sterile plants which exhibit cytoplasmic herbicide tolerance to at least one Type A herbicide and exhibit tolerance to at least one Type B herbicide which is attributable solely to homozygous dominant nuclear genes and male fertile plants which are homozygous recessive maintainer plants for the cytoplasmic male sterile plants and which lack the cytoplasmic herbicide tolerance to at least one Type A herbicide and exhibit tolerance to at least one Type B herbicide attributable solely to the homozygous dominant nuclear genes.

  10. Herbicide safeners: uses, limitations, metabolism, and mechanisms of action.

    PubMed

    Abu-Qare, Aqel W; Duncan, Harry J

    2002-09-01

    Several methods were examined to minimize crops injury caused by herbicides. Thus increase their selectivity. A selective herbicide is one that controls weeds at rates that do not injure the crop. Herbicides are selective in a particular crop within certain limits imposed by the herbicide, the plant, the application rate, the method and time of application, and environment conditions. Herbicide safeners are compounds of diverse chemical families. They are applied with herbicides to protect crops against their injury. Using chemical safeners offer practical, efficient and simple method of improving herbicide selectivity. This method has been applied successfully in cereal crops such as maize, rice and sorghum, against pre-emergence thiocarbamate and chloroacetanilide herbicides. Some reports indicate promising results for the development of safeners for post-emergence herbicides in broadleaved crops. Various hypotheses were proposed explaining mechanisms of action of herbicide safeners: interference with uptake and translocation of the herbicide, alteration in herbicide metabolism, and competition at site of action of the herbicide. Even though progress was made in the development of herbicide safeners and in understanding their mechanisms of action, more research is needed to elucidate clearly how these chemicals act and why their activity is restricted to particular crops and herbicides. PMID:12222792

  11. ENZYMATIC COUPLING OF THE HERBICIDE BENTAZON WITH HUMUS MONOMERS AND CHARACTERIZATION OF REACTION PRODUCTS (R823847)

    EPA Science Inventory

    To elucidate the binding mechanism of the herbicide bentazon
    (3-isopropyl-1H-2,1,3-benzothiadiazine-4(3H)-one 2,2-dioxide) with
    humic monomers in the presence of an oxidative enzyme, the reaction of bentazon
    with catechol, caffeic acid, protocatechuic...

  12. Peanut response to naturally-derived herbicides used in organic crop production

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Weed-free irrigated trials were conducted in 2004 and 2005 to quantify phytotoxic effects of herbicides with the potential to be used in organic peanut production. Clove oil and citric plus acetic acid were each applied at vegetative emergence of peanut (VE), two weeks after VE (2 wk), four weeks a...

  13. Assessment of herbicide sorption by biochars and organic matter associated with soil and sediment

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sorption of two herbicides, fluridone (FLUN) and norflurazon (NORO), by whole sediment, two types of biochars and various soil/sediment organic matter (OM) fractions including nonhydrolyzable carbon (NHC), black carbon (BC) and humic acid (HA) was examined. The single-point organic carbon (OC)-norma...

  14. Robust crop resistance to broadleaf and grass herbicides provided by aryloxyalkanoate dioxygenase transgenes.

    PubMed

    Wright, Terry R; Shan, Guomin; Walsh, Terence A; Lira, Justin M; Cui, Cory; Song, Ping; Zhuang, Meibao; Arnold, Nicole L; Lin, Gaofeng; Yau, Kerrm; Russell, Sean M; Cicchillo, Robert M; Peterson, Mark A; Simpson, David M; Zhou, Ning; Ponsamuel, Jayakumar; Zhang, Zhanyuan

    2010-11-23

    Engineered glyphosate resistance is the most widely adopted genetically modified trait in agriculture, gaining widespread acceptance by providing a simple robust weed control system. However, extensive and sustained use of glyphosate as a sole weed control mechanism has led to field selection for glyphosate-resistant weeds and has induced significant population shifts to weeds with inherent tolerance to glyphosate. Additional weed control mechanisms that can complement glyphosate-resistant crops are, therefore, urgently needed. 2,4-dichlorophenoxyacetic acid (2,4-D) is an effective low-cost, broad-spectrum herbicide that controls many of the weeds developing resistance to glyphosate. We investigated the substrate preferences of bacterial aryloxyalkanoate dioxygenase enzymes (AADs) that can effectively degrade 2,4-D and have found that some members of this class can act on other widely used herbicides in addition to their activity on 2,4-D. AAD-1 cleaves the aryloxyphenoxypropionate family of grass-active herbicides, and AAD-12 acts on pyridyloxyacetate auxin herbicides such as triclopyr and fluroxypyr. Maize plants transformed with an AAD-1 gene showed robust crop resistance to aryloxyphenoxypropionate herbicides over four generations and were also not injured by 2,4-D applications at any growth stage. Arabidopsis plants expressing AAD-12 were resistant to 2,4-D as well as triclopyr and fluroxypyr, and transgenic soybean plants expressing AAD-12 maintained field resistance to 2,4-D over five generations. These results show that single AAD transgenes can provide simultaneous resistance to a broad repertoire of agronomically important classes of herbicides, including 2,4-D, with utility in both monocot and dicot crops. These transgenes can help preserve the productivity and environmental benefits of herbicide-resistant crops. PMID:21059954

  15. Occurrence and load of selected herbicides and metabolites in the lower Mississippi River

    USGS Publications Warehouse

    Clark, G.M.; Goolsby, D.A.

    2000-01-01

    Analyses of water samples collected from the Mississippi River at Baton Rouge, Louisiana, during 1991-1997 indicate that hundreds of metric tons of herbicides and herbicide metabolites are being discharged annually to the Gulf of Mexico. Atrazine, metolachlor, and the ethane-sulfonic acid metabolite of alachlor (alachlor ESA) were the most frequently detected herbicides and, in general, were present in the largest concentrations. Almost 80% of the annual herbicide load to the Gulf of Mexico occurred during the growing season from May to August. The concentrations and loads of alachlor in the Mississippi River decreased dramatically after 1993 in response to decreased use in the basin. In contrast, the concentrations and loads of acetochlor increased after 1994, reflecting its role as a replacement for alachlor. The peak annual herbicide load occurred in 1993, when approximately 640 metric tons (t) of atrazine, 320 t of cyanazine, 215 t of metolachlor, 53 t of simazine, and 50 t of alachlor were discharged to the Gulf of Mexico. The annual loads of atrazine and cyanazine were generally 1-2% of the amount annually applied in the Mississippi River drainage basin; the annual loads of acetochlor, alachlor, and metolachlor were generally less than 1%. Despite a reduction in atrazine use, historical data do not indicate a long-term downward trend in the atrazine load to the Gulf of Mexico. Although a relation (r2=0.62) exists between the atrazine load and stream discharge during May to August, variations in herbicide use and rainfall patterns within subbasins can have a large effect on herbicide loads in the Mississippi River Basin and probably explain a large part of the annual variation in atrazine load to the Gulf of Mexico. Copyright (C) 2000 Elsevier Science B.V.

  16. Response of multiple seeded cocklebur and other cocklebur types to herbicide treatment.

    PubMed

    Abbas, Hamed K; Johnson, Bobbie J; Pantone, Dan J; Wax, Loyd M; Hine, Ron; Shier, W Thomas

    2005-07-01

    Multiple seeded cocklebur has been found in the last decade in Texas, and described as a biotype of Xanthium strumarium L with up to 25 seeds per bur instead of the usual two. The multiple seeded bur typically produces up to nine seedlings, causing concern that it may be harder to control than normal seeded common cocklebur. The efficacies of a series of fungal and conventional commercial herbicides have been compared in the greenhouse on seedlings of multiple seeded cocklebur from Texas (MSC-TX) and normal common cockleburs from Texas (NCC-TX), Arkansas (NCC-AR), Illinois (NCC-ILL) and two from Mississippi (NCC-MS#1, NCC-MS#2). Three measures of herbicidal activity (reductions in plant height and dry weight, and mortality) were used. The fungal herbicide Alternaria helianthi (Hansf) Tubaki & Nishihara at 1 x 10(5) conidia ml(-1) + 2 g liter(-1) Silwet L-77 with an 8-h dew period was an effective herbicide with all biotypes, as were the commercial chemical herbicides chlorimuron (14.8 g ha(-1)), imazaquin (29.6 g ha(-1)), sodium hydrogen methylarsonate (MSMA; 279.1 g ha(-1)) and imazethapyr (39.5 g ha(-1)). The membrane-disrupting organic arsenical MSMA was effective with all biotypes, whereas commercial chemical herbicides which act by inhibiting branched-chain amino acid synthesis (chlorimuron, imazaquin and imazethapyr) were less effective against normal seeded common cocklebur biotypes with short stature. These studies showed that multiple seeded cocklebur was at least as susceptible to the biological agent A helianthi and to the conventional commercial herbicides studied as were normal seeded cockleburs, suggesting that existing methods should be adequate to control this novel biotype. PMID:15712354

  17. Robust crop resistance to broadleaf and grass herbicides provided by aryloxyalkanoate dioxygenase transgenes

    PubMed Central

    Wright, Terry R.; Shan, Guomin; Walsh, Terence A.; Lira, Justin M.; Cui, Cory; Song, Ping; Zhuang, Meibao; Arnold, Nicole L.; Lin, Gaofeng; Yau, Kerrm; Russell, Sean M.; Cicchillo, Robert M.; Peterson, Mark A.; Simpson, David M.; Zhou, Ning; Ponsamuel, Jayakumar; Zhang, Zhanyuan

    2010-01-01

    Engineered glyphosate resistance is the most widely adopted genetically modified trait in agriculture, gaining widespread acceptance by providing a simple robust weed control system. However, extensive and sustained use of glyphosate as a sole weed control mechanism has led to field selection for glyphosate-resistant weeds and has induced significant population shifts to weeds with inherent tolerance to glyphosate. Additional weed control mechanisms that can complement glyphosate-resistant crops are, therefore, urgently needed. 2,4-dichlorophenoxyacetic acid (2,4-D) is an effective low-cost, broad-spectrum herbicide that controls many of the weeds developing resistance to glyphosate. We investigated the substrate preferences of bacterial aryloxyalkanoate dioxygenase enzymes (AADs) that can effectively degrade 2,4-D and have found that some members of this class can act on other widely used herbicides in addition to their activity on 2,4-D. AAD-1 cleaves the aryloxyphenoxypropionate family of grass-active herbicides, and AAD-12 acts on pyridyloxyacetate auxin herbicides such as triclopyr and fluroxypyr. Maize plants transformed with an AAD-1 gene showed robust crop resistance to aryloxyphenoxypropionate herbicides over four generations and were also not injured by 2,4-D applications at any growth stage. Arabidopsis plants expressing AAD-12 were resistant to 2,4-D as well as triclopyr and fluroxypyr, and transgenic soybean plants expressing AAD-12 maintained field resistance to 2,4-D over five generations. These results show that single AAD transgenes can provide simultaneous resistance to a broad repertoire of agronomically important classes of herbicides, including 2,4-D, with utility in both monocot and dicot crops. These transgenes can help preserve the productivity and environmental benefits of herbicide-resistant crops. PMID:21059954

  18. Proximity to Crops and Residential Exposure to Agricultural Herbicides in Iowa

    PubMed Central

    Ward, Mary H.; Lubin, Jay; Giglierano, James; Colt, Joanne S.; Wolter, Calvin; Bekiroglu, Nural; Camann, David; Hartge, Patricia; Nuckols, John R.

    2006-01-01

    Rural residents can be exposed to agricultural pesticides through the proximity of their homes to crop fields. Previously, we developed a method to create historical crop maps using a geographic information system. The aim of the present study was to determine whether crop maps are useful for predicting levels of crop herbicides in carpet dust samples from residences. From homes of participants in a case–control study of non-Hodgkin lymphoma in Iowa (1998–2000), we collected vacuum cleaner dust and measured 14 herbicides with high use on corn and soybeans in Iowa. Of 112 homes, 58% of residences had crops within 500 m of their home, an intermediate distance for primary drift from aerial and ground applications. Detection rates for herbicides ranged from 0% for metribuzin and cyanazine to 95% for 2,4-dichlorophenoxyacetic acid. Six herbicides used almost exclusively in agriculture were detected in 28% of homes. Detections and concentrations were highest in homes with an active farmer. Increasing acreage of corn and soybean fields within 750 m of homes was associated with significantly elevated odds of detecting agricultural herbicides compared with homes with no crops within 750 m (adjusted odds ratio per 10 acres = 1.06; 95% confidence interval, 1.02–1.11). Herbicide concentrations also increased significantly with increasing acreage within 750 m. We evaluated the distance of crop fields from the home at < 100, 101–250, 251–500, and 501–750 m. Including the crop buffer distance parameters in the model did not significantly improve the fit compared with a model with total acres within 750 m. Our results indicate that crop maps may be a useful method for estimating levels of herbicides in homes from nearby crop fields. PMID:16759991

  19. Glyphosate surfactant herbicide poisoning and management.

    PubMed

    Mahendrakar, Kranthi; Venkategowda, Pradeep M; Rao, S Manimala; Mutkule, Dnyaneshwar P

    2014-05-01

    Glyphosate is a widely used herbicide in agriculture, forestry, industrial weed control and aquatic environments. Glyphosate potential as herbicide was first reported in 1971. It is a non-selective herbicide. It can cause a wide range of clinical manifestations in human beings like skin and throat irritation to hypotension, oliguria and death. We are reporting a case of a 35-year-old male patient who was admitted to our tertiary care hospital following intentional ingestion of around 200 ml of herbicide containing glyphosate. Initially, gastric lavage done and the patient was managed with intubation and mechanical ventilation, noradrenaline and vasopressin infusion, continuous veno-venous hemodiafiltration and intravenous (IV) lipid emulsion (20% intralipid 100 ml), patient was successfully treated and discharged home. This case report emphasizes on timely systemic supportive measure as a sole method of treatment since this poison has no known specific antidote and the use of IV lipid emulsion for a successful outcome. PMID:24914265

  20. Glyphosate, other herbicides, and transformation products in Midwestern streams, 2002

    USGS Publications Warehouse

    Battaglin, W.A.; Kolpin, D.W.; Scribner, E.A.; Kuivila, K.M.; Sandstrom, M.W.

    2005-01-01

    The use of glyphosate has increased rapidly, and there is limited understanding of its environmental fate. The objective of this study was to document the occurrence of glyphosate and the transformation product aminomethylphosphonic acid (AMPA) in Midwestern streams and to compare their occurrence with that of more commonly measured herbicides such as acetochlor, atrazine, and metolachlor. Water samples were collected at sites on 51 streams in nine Midwestern states in 2002 during three runoff events: after the application of pre-emergence herbicides, after the application of post-emergence herbicides, and during harvest season. All samples were analyzed for glyphosate and 20 other herbicides using gas chromatography/mass spectrometry or high performance liquid chromatography/mass spectrometry. The frequency of glyphosate and AMPA detection, range of concentrations in runoff samples, and ratios of AMPA to glyphosate concentrations did not vary throughout the growing season as substantially as for other herbicides like atrazine, probably because of different seasonal use patterns. Glyphosate was detected at or above 0.1 μg/1 in 35 percent of pre-emergence, 40 percent of post-emergence, and 31 percent of harvest season samples, with a maximum concentration of 8.7 μg/1. AMPA was detected at or above 0.1 μg/1 in 53 percent of pre-emergence, 83 percent of post-emergence, and 73 percent of harvest season samples, with a maximum concentration of 3.6 μg/1. Glyphosate was not detected at a concentration at or above the U.S. Environmental Protection Agency's maximum contamination level (MCL) of 700 μg/1 in any sample. Atrazine was detected at or above 0.1 μg/1 in 94 percent of pre-emergence, 96 percent of post-emergence, and 57 percent of harvest season samples, with a maximum concentration of 55 μg/1. Atrazine was detected at or above its MCL (3 μg/1) in 57 percent of pre-emergence and 33 percent of post-emergence samples

  1. Electronic structure of herbicides: Atrazine and bromoxynil

    NASA Astrophysics Data System (ADS)

    Novak, Igor; Kovač, Branka

    2011-06-01

    The electronic structures of herbicides atrazine and bromoxynil have been investigated by UV photoelectron spectroscopy (UPS), quantum chemical calculations and comparison with X-ray diffraction, molecular docking and molecular dynamics studies. Their electronic and molecular structures are discussed in the context of their biological activity. This is the first report which correlates the molecular mechanism of biological activity of these herbicides with their experimentally determined electronic and molecular structures.

  2. Core-shell magnetic molecularly imprinted polymers as sorbent for sulfonylurea herbicide residues.

    PubMed

    Miao, Shan Shan; Wu, Mei Sheng; Zuo, Hai Gen; Jiang, Chen; Jin, She Feng; Lu, Yi Chen; Yang, Hong

    2015-04-15

    Sulfonylurea herbicides are widely used at lower dosage for controlling broad-leaf weeds and some grasses in cereals and economic crops. It is important to develop a highly efficient and selective pretreatment method for analyzing sulfonylurea herbicide residues in environments and samples from agricultural products based on magnetic molecularly imprinted polymers (MIPs). The MIPs were prepared by a surface molecular imprinting technique especially using the vinyl-modified Fe3O4@SiO2 nanoparticle as the supporting matrix, bensulfuron-methyl (BSM) as the template molecule, methacrylic acid (MAA) as a functional monomer, trimethylolpropane trimethacrylate (TRIM) as a cross-linker, and azodiisobutyronitrile (AIBN) as an initiator. The MIPs show high affinity, recognition specificity, fast mass transfer rate, and efficient adsorption performance toward BSM with the adsorption capacity reaching up to 37.32 mg g(-1). Furthermore, the MIPs also showed cross-selectivity for herbicides triasulfuron (TS), prosulfuron (PS), and pyrazosulfuron-ethyl (PSE). The MIP solid phase extraction (SPE) column was easier to operate, regenerate, and retrieve compared to those of C18 SPE column. The developed method showed highly selective separation and enrichment of sulfonylurea herbicide residues, which enable its application in the pretreatment of multisulfonylurea herbicide residues. PMID:25797565

  3. Protective responses induced by herbicide safeners in wheat

    PubMed Central

    Taylor, Victoria L.; Cummins, Ian; Brazier-Hicks, Melissa; Edwards, Robert

    2013-01-01

    Safeners are agrochemicals which enhance tolerance to herbicides in cereals including wheat (Triticum aestivum L.) by elevating the expression of xenobiotic detoxifying enzymes, such as glutathione transferases (GSTs). When wheat plants were spray-treated with three safener chemistries, namely cloquintocet mexyl, mefenpyr diethyl and fenchlorazole ethyl, an apparently identical subset of GSTs derived from the tau, phi and lambda classes accumulated in the foliage. Treatment with the closely related mefenpyr diethyl and fenchlorazole ethyl enhanced seedling shoot growth, but this effect was not determined with the chemically unrelated cloquintocet mexyl. Focussing on cloquintocet mexyl, treatments were found to only give a transient induction of GSTs, with the period of elevation being dose dependent. Examining the role of safener metabolism in controlling these responses, it was determined that cloquintocet mexyl was rapidly hydrolysed to the respective carboxylic acid. Studies with cloquintocet showed that the acid was equally effective at inducing GSTs as the ester and appeared to be the active safener. Studies on the tissue induction of GSTs showed that whilst phi and tau class enzymes were induced in all tissues, the induction of the lambda enzymes was restricted to the meristems. To test the potential protective effects of cloquintocet mexyl in wheat on chemicals other than herbicides, seeds were pre-soaked in safeners prior to sowing on soil containing oil and a range of heavy metals. Whilst untreated seeds were unable to germinate on the contaminated soil, safener treatments resulted in seedlings briefly growing before succumbing to the pollutants. Our results show that safeners exert a range of protective and growth promoting activities in wheat that extend beyond enhancing tolerance to herbicides. PMID:23564986

  4. METHOD 535: MEASUREMENT OF CHLOROACETANILIDE AND CHLOROACETAMIDE HERBICIDE DEGRADATES IN DRINKING WATER BY SOLID PHASE EXTRACTION AND LIQUID CHROMATOGRAPHY/TANDEM MASS SPECTROMETRY (LC/MS/MS)

    EPA Science Inventory

    Over the past several years, ethanesulfonic acid (ESA) and oxanilic acid (OA) degradation products of acetanilide/acetamide herbicides have been found in U.S. ground waters and surface waters. The substitution of the sulfonic acid or the carbonic acid for the chlorine atom great...

  5. Pea (Pisum sativum) seed production as an assay for reproductive effects due to herbicides.

    PubMed

    Olszyk, David; Pfleeger, Thomas; Lee, E Henry; Plocher, Milton

    2009-09-01

    Even though herbicide drift can affect plant reproduction, current plant testing protocols emphasize effects on vegetative growth. In this study, we determined whether a short-growing season plant can indicate potential effects of herbicides on seed production. Pea (Pisum sativum cv. Dakota) plants were grown in mineral soil in pots under greenhouse conditions. Plants were treated with a variety of herbicides (dicamba, clopyralid, glufosinate, glyphosate, 2-methyl-4-chlorophenoxyacetic acid, primisulfuron, or sulfometuron) at below standard field application rates applied at a vegetative stage of growth (approximately 14 d after emergence) or at flowering (approximately 20 d after emergence). Pea seed production was greatly reduced by sulfometuron at the minimum concentration used (0.001 x field application rate), with an effective concentration producing a 25% reduction in seed dry weight of 0.00007 x field application rate. Primisulfuron and glyphosate had a 25% reduction in seed dry weight for seed dry weight of 0.0035 and 0.0096 x field application rate, respectively. Clopyralid and dicamba reduced pea seed dry weight at a 25% reduction in seed dry weight of approximately 0.07 x field application rate. Glufosinate only reduced pea seed weight in one experiment, with a 25% reduction in seed dry weight of 0.07 and 0.008 x field application rate at vegetative growth and flowering stages, respectively. Pea seed dry weight was not affected by 2-methyl-4-chlorophenoxyacetic acid. Plant developmental stage had no consistent effect on herbicide responses. Reduced seed production occurred with some herbicides (especially acetolactate synthase inhibitors), which caused little or no reduction in plant height or shoot biomass and little visible injury. Thus, pea may be a model species to indicate seed reproductive responses to herbicides, with seed production obtained by extending plant growth for usually only 7 d longer than the period usually used in the vegetative vigor

  6. Genetically Modified Herbicide-Tolerant Crops, Weeds, and Herbicides: Overview and Impact.

    PubMed

    Bonny, Sylvie

    2016-01-01

    Genetically modified (GM) crops have been and continue to be a subject of controversy despite their rapid adoption by farmers where approved. For the last two decades, an important matter of debate has been their impact on pesticide use, particularly for herbicide-tolerant (HT) crops. Some claim that these crops bring about a decrease in herbicide use, while others claim the opposite. In fact, since 1996, most cultivated GMOs have been GMHT crops, which involve the use of an associated herbicide, generally glyphosate. In their very first years of adoption, HT crops often led to some decrease in herbicide use. However, the repetition of glyphosate-tolerant crops and of glyphosate only applications in the same fields without sufficient alternation and herbicide diversity has contributed to the appearance of glyphosate-resistant weeds. These weeds have resulted in a rise in the use of glyphosate and other herbicides. This article explores this situation and the impacts of herbicide-resistant weeds, using an interdisciplinary approach and drawing on recent data. The paper analyzes the spread of GMHT crops worldwide and their consequences on herbicide use in the USA in particular. It then addresses the global development of glyphosate-resistant weeds and their impact, particularly focusing on the USA. Finally, the last section explores how industry, farmers, and weed scientists are coping with the spread of resistant weeds. The concluding comments deal more widely with trends in GM crops. PMID:26296738

  7. Genetically Modified Herbicide-Tolerant Crops, Weeds, and Herbicides: Overview and Impact

    NASA Astrophysics Data System (ADS)

    Bonny, Sylvie

    2016-01-01

    Genetically modified (GM) crops have been and continue to be a subject of controversy despite their rapid adoption by farmers where approved. For the last two decades, an important matter of debate has been their impact on pesticide use, particularly for herbicide-tolerant (HT) crops. Some claim that these crops bring about a decrease in herbicide use, while others claim the opposite. In fact, since 1996, most cultivated GMOs have been GMHT crops, which involve the use of an associated herbicide, generally glyphosate. In their very first years of adoption, HT crops often led to some decrease in herbicide use. However, the repetition of glyphosate-tolerant crops and of glyphosate only applications in the same fields without sufficient alternation and herbicide diversity has contributed to the appearance of glyphosate-resistant weeds. These weeds have resulted in a rise in the use of glyphosate and other herbicides. This article explores this situation and the impacts of herbicide-resistant weeds, using an interdisciplinary approach and drawing on recent data. The paper analyzes the spread of GMHT crops worldwide and their consequences on herbicide use in the USA in particular. It then addresses the global development of glyphosate-resistant weeds and their impact, particularly focusing on the USA. Finally, the last section explores how industry, farmers, and weed scientists are coping with the spread of resistant weeds. The concluding comments deal more widely with trends in GM crops.

  8. Cross-resistance pattern and alternative herbicides for Cyperus difformis resistant to sulfonylurea herbicides in Korea.

    PubMed

    Kuk, Yong In; Kim, Kyung Hyun; Kwon, Oh Do; Lee, Do Jin; Burgos, Nilda R; Jung, Sunyo; Guh, Ja Ock

    2004-01-01

    A Cyperus difformis L accession from Chonnam province, Korea was tested for resistance to the sulfonylurea herbicide, imazosulfuron. The accession was confirmed to be resistant (R) and was cross-resistant to other sulfonylurea herbicides, bensulfuron-methyl, cyclosulfamuron and pyrazosulfuron-ethyl, the pyrimidinyl thiobenzoate herbicide, bispyribac-sodium, and the imidazolinone herbicide imazapyr, but not to imazaquin. Multiple resistance was tested using twelve herbicides with target sites other than acetolactate synthase (ALS). The R biotype could be controlled by other herbicides with different modes of action such as butachlor, carfentrazone-ethyl, clomeprop, dithiopyr, esprocarb, mefenacet, oxadiazon, pretilachlor, pyrazolate and thiobencarb, applied to soil at recommended rates. Several sulfonylurea herbicide-based mixtures can control both the R and S biotypes of C difformis, except sulfonylurea plus dimepiperate, molinate or pyriftalid, and pyrazolate plus butachlor. Although mixtures of sulfonylurea herbicides might be more effective, they should be avoided and used only in special cases. In terms of in vitro ALS activity, the R biotype was 1139-, 3583-, 1482-, 416-, 5- and 9-fold more resistant to bensulfuron-methyl, cyclosulfamuron, imazosulfuron, pyrazosulfuron-ethyl, bispyribac-sodium and imazapyr, respectively, than the S biotype. The in vivo ALS activity of the R biotype was also less affected by the sulfonylurea herbicides, imazosulfuron and pyrazosulfuron-ethyl, than the S biotype. Results of in vitro and in vivo ALS assays indicated that the resistance mechanism of C difformis to ALS inhibitor herbicides was primarily due to an alteration in the target enzyme, ALS. Greenhouse experiments showed delayed flowering and reduced seed production of the R biotype, which could possibly result in reduced fitness. This unusual observation needs to be confirmed in field situations. PMID:14727745

  9. The chiral herbicide beflubutamid (I): Isolation of pure enantiomers by HPLC, herbicidal activity of enantiomers, and analysis by enantioselective GC-MS.

    PubMed

    Buerge, Ignaz J; Bächli, Astrid; De Joffrey, Jean-Pierre; Müller, Markus D; Spycher, Simon; Poiger, Thomas

    2013-07-01

    For many chiral pesticides, little information is available on the properties and fate of individual stereoisomers. A basic data set would, first of all, include stereoisomer-specific analytical methods and data on the biological activity of stereoisomers. The herbicide beflubutamid, which acts as an inhibitor of carotenoid biosynthesis, is currently marketed as racemate against dicotyledonous weeds in cereals. Here, we present analytical methods for enantiomer separation of beflubutamid and two metabolites based on chiral HPLC. These methods were used to assign the optical rotation and to prepare milligram quantities of the pure enantiomers for further characterization with respect to herbicidal activity. In addition, sensitive analytical methods were developed for enantiomer separation and quantification of beflubutamid and its metabolites at trace level, using chiral GC-MS. In miniaturized biotests with garden cress, (-)-beflubutamid showed at least 1000× higher herbicidal activity (EC50, 0.50 μM) than (+)-beflubutamid, as determined by analysis of chlorophyll a in 5-day-old leaves. The agricultural use of enantiopure (-)-beflubutamid rather than the racemic compound may therefore be advantageous from an environmental perspective. In further biotests, the (+)-enantiomer of the phenoxybutanoic acid metabolite showed effects on root growth, possibly via an auxin-type mode of action, but at 100× higher concentrations than the structurally related herbicide (+)-mecoprop. PMID:22849576

  10. Reconnaissance data for glyphosate, other selected herbicides, their degradation products, and antibiotics in 51 streams in nine midwestern states, 2002

    USGS Publications Warehouse

    Scribner, Elisabeth A.; Battaglin, William A.; Dietze, Julie E.; Thurman, E.M.

    2003-01-01

    Since 1989, the U.S. Geological Survey has conducted periodic reconnaissance studies of streams in the Midwestern United States to determine the geographic and seasonal distribution of herbicide compounds. These studies have documented that large amounts of acetochlor, alachlor, atrazine, cyanazine, metolachlor, and their degradation products are flushed into streams during post-application runoff. Additional studies show that peak herbicide concentrations tend to occur during the first runoff after herbicide application and that herbicide flushes can occur during runoff for several weeks to months following application. Since the first stream study conducted in 1989, several significant changes in herbicide use have occurred. The most substantial change is the tripling in the use of glyphosate during the past 5 years. Over this same time period (1997-2001), usage of acetochlor and atrazine increased slightly, whereas alachlor, cyanazine, and metolachlor usage decreased. During 2002, 154 samples were collected from 51 streams in nine Midwestern States during three periods of runoff. This report provides a compilation of the analytical results of five laboratory methods. Results show that glyphosate was detected in 55 (36 percent) of the samples, and aminomethylphosphonic acid (a degradation product of glyphosate) was detected in 107 (69 percent) of the samples. Atrazine, the most frequently detected herbicide, was found in 93 percent of the samples, followed by metolachlor, found in 73 percent of the samples; metolachlor ethanesulfonic acid (ESA) and oxanilic acid (OXA) were the most frequently detected herbicide degradation products, both being found in more than 95 percent of the samples. The data presented here are valuable for comparison with results from the earlier reconnaissance studies.

  11. Environmental impact of herbicide regimes used with genetically modified herbicide-resistant maize.

    PubMed

    Devos, Yann; Cougnon, Mathias; Vergucht, Sofie; Bulcke, Robert; Haesaert, Geert; Steurbaut, Walter; Reheul, Dirk

    2008-12-01

    With the potential advent of genetically modified herbicide-resistant (GMHR) crops in the European Union, changes in patterns of herbicide use are predicted. Broad-spectrum, non-selective herbicides used with GMHR crops are expected to substitute for a set of currently used herbicides, which might alter the agro-environmental footprint from crop production. To test this hypothesis, the environmental impact of various herbicide regimes currently used with non-GMHR maize in Belgium was calculated and compared with that of possible herbicide regimes applied in GMHR maize. Impacts on human health and the environment were calculated through the pesticide occupational and environmental risk (POCER) indicator. Results showed that the environmental impact of herbicide regimes solely relying on the active ingredients glyphosate (GLY) or glufosinate-ammonium (GLU) is lower than that of herbicide regimes applied in non-GMHR maize. Due to the lower potential of GLY and GLU to contaminate ground water and their lower acute toxicity to aquatic organisms, the POCER exceedence factor values for the environment were reduced approximately by a sixth when GLY or GLU is used alone. However, the environmental impact of novel herbicide regimes tested may be underestimated due to the assumption that active ingredients used with GMHR maize would be used alone. Data retrieved from literature suggest that weed control efficacy is increased and resistance development delayed when GLY or GLU is used together with other herbicides in the GMHR system. Due to the partial instead of complete replacement of currently used herbicide regimes, the beneficial environmental impact of novel herbicide regimes might sometimes be reduced or counterbalanced. Despite the high weed control efficacy provided by the biotechnology-based weed management strategy, neither indirect harmful effects on farmland biodiversity through losses in food resources and shelter, nor shifts in weed communities have been

  12. Cultural control of weeds in herbicide-free annual forages

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The adoption of zero tillage systems improves soil water conservation, allowing for increased crop intensification and diversification in the semiarid northern Great Plains. Zero tillage systems rely primarily on herbicides for weed management, increasing selection pressure for herbicide resistance...

  13. Synthesis and Biological Activity Evaluation of Novel α-Amino Phosphonate Derivatives Containing a Pyrimidinyl Moiety as Potential Herbicidal Agents.

    PubMed

    Chen, Jin-Long; Tang, Wu; Che, Jian-Yi; Chen, Kai; Yan, Gang; Gu, Yu-Cheng; Shi, De-Qing

    2015-08-19

    To find novel high-activity and low-toxicity herbicide lead compounds with novel herbicidal mode of action, series of novel α-amino phosphonate derivatives containing a pyrimidinyl moiety, I, II, III, and IV, were designed and synthesized by Lewis acid (magnesium perchlorate) catalyzed Mannich-type reaction of aldehydes, amines, and phosphites. Their structures were clearly identified by spectroscopy data (IR, (1)H NMR, (31)P NMR, EI-MS) and elemental analyses. The bioassay [in vitro, in vivo (GH1 and GH2)] showed that most compounds I exhibited good herbicidal activities; for example, the activities of compounds Ib, Ic, Ig, Ii, Ik, and Im were as good as the positive control herbicides (acetochlor, atrazine, mesotrione, and glyphosate). However, their structural isomers II and III and analogues IV did not display any herbicidal activities in vivo, although some of them possessed selective inhibitory activity against Arabidopsis thaliana in vitro. Interestingly, it was found that compounds IVs, IVt, and IVl showed selective insecticidal activities against Aphis species or Plutella xylostella, respectively. Their preliminary herbicidal mode of action and structure-activity relationships were also studied. PMID:26222653

  14. Inhibition of acetyl-coenzyme A carboxylase by two classes of grass-selective herbicides

    SciTech Connect

    Rendina, A.R.; Craig-Kennard, A.C.; Beaudoin, J.D.; Breen, M.K. )

    1990-05-01

    The selective grass herbicides diclofop, haloxyfop, and trifop (((aryloxy)phenoxy)propionic acids) and alloxydim, sethoxydim, and clethodim (cyclohexanediones) are potent, reversible inhibitors of acetyl-coenzyme A carboxylase (ACC) partially purified from barley, corn, and wheat. Although inhibition of the wheat enzyme by clethodim and diclofop is noncompetitive versus each of the substrates adenosine triphosphate (ATP), HCO{sub 3}{sup {minus}}, and acetyl-coenzyme A (acetyl-CoA), diclofop and clethodim are nearly competitive versus acetyl-CoA since the level of inhibition is most sensitive to the concentration of acetyl-CoA (K{sub is} < K{sub ii}). To conclusively show whether the herbicides interact at the biotin carboxylation site or the carboxyl transfer site, the inhibition of isotope exchange and partial reactions catalyzed at each site was studied with the wheat enzyme. Only the ({sup 14}C)acetyl-CoA-malonyl-CoA exchange and decarboxylation of ({sup 14}C)malonyl-CoA reactions are strongly inhibited by clethodim and diclofop, suggesting that the herbicides interfere with the carboxyl transfer site rather than the biotin carboxylation site of the enzyme. Double-inhibition studies with diclofop and clethodim suggest that the ((aryloxy)phenoxy)propionic acid and cyclohexanedione herbicides may bind to the same region of the enzyme.

  15. Photosynthesis involvement in the mechanism of action of diphenyl ether herbicides.

    PubMed

    Ensminger, M P; Hess, F D

    1985-05-01

    Photosynthesis is not required for the toxicity of diphenyl ether herbicides, nor are chloroplast thylakoids the primary site of diphenyl ether herbicide activity. Isolated spinach (Spinacia oleracea L.) chloroplast fragments produced malonyl dialdehyde, indicating lipid peroxidation, when paraquat (1,1'-dimethyl-4,4'-bipyridinium ion) or diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea] were added to the medium, but no malonyl dialdehyde was produced when chloroplast fragments were treated with the methyl ester of acifluorfen (methyl 5-[2-chloro-4-(trifluoromethyl)phenoxy]-2-nitrobenzoic acid), oxyfluorfen [2-chloro-1-(3-ethoxy-4-nitrophenoxy)-4-(trifluoromethyl)benzene], or MC15608 (methyl 5-[2-chloro-4-(trifluoromethyl)phenoxy]-2-chlorobenzoate). In most cases the toxicity of acifluorfen-methyl, oxyfluorfen, or MC15608 to the unicellular green alga Chlamydomonas eugametos (Moewus) did not decrease after simultaneous treatment with diuron. However, diuron significantly reduced cell death after paraquat treatment at all but the highest paraquat concentration tested (0.1 millimolar). These data indicate electron transport of photosynthesis is not serving the same function for diphenyl ether herbicides as for paraquat. Additional evidence for differential action of paraquat was obtained from the superoxide scavenger copper penicillamine (copper complex of 2-amino-3-mercapto-3-methylbutanoic acid). Copper penicillamine eliminated paraquat toxicity in cucumber (Cucumis sativus L.) cotyledons but did not reduce diphenyl ether herbicide toxicity. PMID:16664206

  16. Photosynthesis Involvement in the Mechanism of Action of Diphenyl Ether Herbicides 1

    PubMed Central

    Ensminger, Michael P.; Hess, F. Dan

    1985-01-01

    Photosynthesis is not required for the toxicity of diphenyl ether herbicides, nor are chloroplast thylakoids the primary site of diphenyl ether herbicide activity. Isolated spinach (Spinacia oleracea L.) chloroplast fragments produced malonyl dialdehyde, indicating lipid peroxidation, when paraquat (1,1′-dimethyl-4,4′-bipyridinium ion) or diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea] were added to the medium, but no malonyl dialdehyde was produced when chloroplast fragments were treated with the methyl ester of acifluorfen (methyl 5-[2-chloro-4-(trifluoromethyl)phenoxy]-2-nitrobenzoic acid), oxyfluorfen [2-chloro-1-(3-ethoxy-4-nitrophenoxy)-4-(trifluoromethyl)benzene], or MC15608 (methyl 5-[2-chloro-4-(trifluoromethyl)phenoxy]-2-chlorobenzoate). In most cases the toxicity of acifluorfen-methyl, oxyfluorfen, or MC15608 to the unicellular green alga Chlamydomonas eugametos (Moewus) did not decrease after simultaneous treatment with diuron. However, diuron significantly reduced cell death after paraquat treatment at all but the highest paraquat concentration tested (0.1 millimolar). These data indicate electron transport of photosynthesis is not serving the same function for diphenyl ether herbicides as for paraquat. Additional evidence for differential action of paraquat was obtained from the superoxide scavenger copper penicillamine (copper complex of 2-amino-3-mercapto-3-methylbutanoic acid). Copper penicillamine eliminated paraquat toxicity in cucumber (Cucumis sativus L.) cotyledons but did not reduce diphenyl ether herbicide toxicity. PMID:16664206

  17. Effects of a glyphosate-based herbicide on the development of Common toads (Bufo bufo L.; Amphibia) at different temperatures

    NASA Astrophysics Data System (ADS)

    Baier, Fabian; Gruber, Edith; Spangl, Bernhard; Zaller, Johann G.

    2016-04-01

    Herbicides based on the active ingredient glyphosate are frequently applied in agriculture, horticulture and private gardens all over the world. Recently, leaching of glyphosate or its metabolite (AMPA) into water bodies inhabited by amphibians has been reported. However, very little is known about non-target effects of these herbicides on amphibians and even less is known to what extent different temperatures might alter these effects. Using climate chambers, we investigated the effects of the glyphosate-based herbicide Roundup PowerFlex® (480 g L-1 glyphosate, formulated as 588 g L-1 potassium salt) on the larval development of Common toads (Bufo bufo L.; Amphibia: Anura) under different temperature regimes (15°C vs. 20°C). We established five herbicide concentrations: 0, 1.5, 3, 4 mg acid equivalent L-1 and a 4 mg a.e. L-1 pulse treatment (totally three applications of 1.5, 1.5 and another 1 mg a.e. L-1) at each temperature in a full-factorial design. Each treatment combination was replicated five times, the experiment ran for 24 days. Results showed a highly significant effect of temperature on body length and body width but no effect of herbicide concentration on these growth parameters. Moreover, highly significant interactions between herbicide and temperature on body length and body width were observed suggesting that herbicides had different effects on different temperatures. In conclusion, although Roundup PowerFlex® at the tested concentrations appeared to have no acute toxicity to larvae of Common toads, the observed effects on tadpole morphology will potentially affect competitive interactions in spawning ponds of amphibia. Our findings of herbicide x temperature interactions might become more prevalent when human-induced climate change will lead to more extreme temperatures.

  18. Effects of the herbicide dicamba on nontarget plants and pollinator visitation.

    PubMed

    Bohnenblust, Eric W; Vaudo, Anthony D; Egan, J Franklin; Mortensen, David A; Tooker, John F

    2016-01-01

    Nearly 80% of all pesticides applied to row crops are herbicides, and these applications pose potentially significant ecotoxicological risks to nontarget plants and associated pollinators. In response to the widespread occurrence of weed species resistant to glyphosate, biotechnology companies have developed crops resistant to the synthetic-auxin herbicides dicamba and 2,4-dichlorophenoxyacetic acid (2,4-D); and once commercialized, adoption of these crops is likely to change herbicide-use patterns. Despite current limited use, dicamba and 2,4-D are often responsible for injury to nontarget plants; but effects of these herbicides on insect communities are poorly understood. To understand the influence of dicamba on pollinators, the authors applied several sublethal, drift-level rates of dicamba to alfalfa (Medicago sativa L.) and Eupatorium perfoliatum L. and evaluated plant flowering and floral visitation by pollinators. The authors found that dicamba doses simulating particle drift (≈1% of the field application rate) delayed onset of flowering and reduced the number of flowers of each plant species; however, plants that did flower produced similar-quality pollen in terms of protein concentrations. Further, plants affected by particle drift rates were visited less often by pollinators. Because plants exposed to sublethal levels of dicamba may produce fewer floral resources and be less frequently visited by pollinators, use of dicamba or other synthetic-auxin herbicides with widespread planting of herbicide-resistant crops will need to be carefully stewarded to prevent potential disturbances of plant and beneficial insect communities in agricultural landscapes. PMID:26184786

  19. Unintended effects of the herbicides 2,4-D and dicamba on lady beetles.

    PubMed

    Freydier, Laurène; Lundgren, Jonathan G

    2016-08-01

    Weed resistance to glyphosate and development of new GM crops tolerant to 2,4-dichlorophenoxyacetic acid (2,4-D) and dicamba is expected to lead to increased use of these herbicides in cropland. The lady beetle, Coleomegilla maculata is an important beneficial insect in cropland that is commonly used as an indicator species in safety evaluations of pesticides. Here, we examined the lethal and non-lethal effects of 2,4-D and dicamba active ingredients and commercial formulations to this lady beetle species, and tested for synergistic effects of the herbicides. Second instars of lady beetles were exposed to an experimental treatment, and their mortality, development, weight, sex ratio, fecundity, and mobility was evaluated. Using similar methods, a dose-response study was conducted on 2,4-D with and without dicamba. The commercial formulation of 2,4-D was highly lethal to lady beetle larvae; the LC90 of this herbicide was 13 % of the label rate. In this case, the "inactive" ingredients were a key driver of the toxicity. Dicamba active ingredient significantly increased lady beetle mortality and reduced their body weight. The commercial formulations of both herbicides reduced the proportion of males in the lady beetle population. The herbicides when used together did not act synergistically in their toxicity toward lady beetles versus when the chemistries were used independently. Our work shows that herbicide formulations can cause both lethal and sublethal effects on non-target, beneficial insects, and these effects are sometimes driven by the "inactive" ingredients. The field-level implications of shifts in weed management practices on insect management programs should receive further attention. PMID:27282375

  20. Herbicide-Resistant Crops: Utilities and Limitations for Herbicide-Resistant Weed Management

    PubMed Central

    2010-01-01

    Since 1996, genetically modified herbicide-resistant (HR) crops, particularly glyphosate-resistant (GR) crops, have transformed the tactics that corn, soybean, and cotton growers use to manage weeds. The use of GR crops continues to grow, but weeds are adapting to the common practice of using only glyphosate to control weeds. Growers using only a single mode of action to manage weeds need to change to a more diverse array of herbicidal, mechanical, and cultural practices to maintain the effectiveness of glyphosate. Unfortunately, the introduction of GR crops and the high initial efficacy of glyphosate often lead to a decline in the use of other herbicide options and less investment by industry to discover new herbicide active ingredients. With some exceptions, most growers can still manage their weed problems with currently available selective and HR crop-enabled herbicides. However, current crop management systems are in jeopardy given the pace at which weed populations are evolving glyphosate resistance. New HR crop technologies will expand the utility of currently available herbicides and enable new interim solutions for growers to manage HR weeds, but will not replace the long-term need to diversify weed management tactics and discover herbicides with new modes of action. This paper reviews the strengths and weaknesses of anticipated weed management options and the best management practices that growers need to implement in HR crops to maximize the long-term benefits of current technologies and reduce weed shifts to difficult-to-control and HR weeds. PMID:20586458

  1. Reduced herbicide leaching by in situ adsorption of herbicide-micelle formulations to soils.

    PubMed

    Katz, Haim; Mishael, Yael G

    2014-01-01

    Aiming to reduce herbicide leaching, "in situ" adsorption of herbicide-micelle formulations to soils was explored. Sulfentrazone or metolachlor were solubilized in cationic micelles, and these herbicide-micelle formulations were applied to sandy and alluvial soils. Sulfentrazone adsorption to the soils was negligible; however, its adsorption via its solubilization in micelles and their adsorption to the soil was significant and in good agreement with the Freundlich and Langmuir models. Adsorption of solubilized herbicide to the sandy soil was higher than to the alluvial soil. The low ratio between the surfactant concentration and the cation exchange capacity (CEC) of the alluvial soil brought upon micelle decomposition and reduction in herbicide adsorption. Therefore, an optimized ratio between surfactant and soil CEC was chosen to maximize herbicide retention. Even upon adding relatively low loadings of surfactant (0.075-0.3% w/w soil), herbicide leaching through the soils was significantly reduced (2-5-fold) in comparison with the commercial formulations. PMID:24295204

  2. Growth regulation and other secondary effects of herbicides

    Technology Transfer Automated Retrieval System (TEKTRAN)

    As all herbicides act on pathways or processes crucial to plants, in an inhibitory or stimulatory way, low doses of any herbicide might be used to beneficially modify plant growth, development, or composition. Glyphosate, the most used herbicide all over the world, is widely applied at low rates to ...

  3. Discovery of new herbicide modes of action with natural phytotoxins

    Technology Transfer Automated Retrieval System (TEKTRAN)

    About 20 modes of action (MOAs) are utilized by commercial herbicides, and almost 30 years have passed since the last new MOA was introduced. Rapidly increasing evolution of resistance to herbicides with these MOAs has greatly increased the need for herbicides with new MOAs. Combinatorial chemistry ...

  4. Tolerance evaluation of vegetatively established Miscanthus x giganteus to herbicides

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In spite of the recent focus on herbicide resistant weeds, herbicide resistant weeds are not new to agriculture; the first herbicide resistant weed was documented in 1957, with the first widespread resistance occurring in common groundsel with atrazine in the early 1970’s. Glyphosate resistant weed...

  5. Strengths and Weaknesses of Two New Potato Herbicides

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Outlook (dimethenamid-p) and Chateau (flumioxazin) are two new preemergence herbicides labeled for use in potatoes. Both herbicides are restricted to preemergence applications only and improve nightshade control when tank mixed with other potato herbicides. Dimethenamid-p is particularly strong on ...

  6. The aquatic ecotoxicology of triazine herbicides

    SciTech Connect

    Giddings, J.M.

    1996-10-01

    Triazine herbicides control plant growth by inhibiting photophosphorylation, but typically do not cause permanent cell damage or death. Effects on aquatic plants are reversible; photosynthesis resumes when the herbicide disappears from the water, and sometimes even while it is still present. Effects on aquatic plant communities are further ameliorated by species replacements, so the communities as a whole are less sensitive than their most sensitive species. Atrazine, a representative triazine herbicide, is toxic to aquatic plants (algae and macrophytes) at concentrations in the range of 20 to 200 {mu}g/L or less. Aquatic invertebrates and fish are much less sensitive than plants, with acute toxicity occurring at 1000 {mu}g/L or higher. Ecologically significant effects in aquatic ecosystems are likely only if plant communities are severely damaged by prolonged exposure to high atrazine concentrations.

  7. Alkylating reactivity and herbicidal activity of chloroacetamides.

    PubMed

    Jablonkai, Istvan

    2003-04-01

    The relationship between S- and N-alkylating reactivity and herbicidal activity within a series of chloroacetamides, including several commercial herbicides and newly synthesised analogues was studied. The S-alkylating reactivity of selected chloroacetamides, as well as those of atrazine and chlorfenprop-methyl, was determined by in vitro GSH conjugation at a ratio of GSH to alkylating agent of 25:1. A spectrophotometric reaction using 4-(4-nitrobenzyl)pyridine was used to characterise the N-alkylating reactivity of the chemicals. Our results indicate that a reduced level of N-alkylating reactivity correlates with an improved herbicidal efficacy at a practical rate. However, the phytoxicity of the molecules is not simply dependent on chemical reactivities, but strictly related to the molecular structure, indicating that lipophilicity, uptake, mobility and induction of detoxifying enzymes may also be decisive factors in the mode of action. PMID:12701706

  8. Exogenous lipoid pneumonia caused by herbicide inhalation.

    PubMed

    Hotta, Takamasa; Tsubata, Yukari; Okimoto, Tamio; Hoshino, Teppei; Hamaguchi, Shun-Ichi; Isobe, Takeshi

    2016-09-01

    Exogenous lipoid pneumonia is caused by aspiration or inhalation of oily substances. Generally, lipoid pneumonia has non-specific clinical and radiological presentations and may be misdiagnosed as bacterial pneumonia. Our patient, a 68-year-old man who had been diagnosed with pneumonia on three previous occasions, was admitted to our hospital with a fourth similar episode. Computed tomography of the chest revealed extensive consolidations with air bronchograms in lung fields on the right side. The bronchoalveolar lavage fluid (BALF) increased ghost-like macrophages that stained positive for lipid. Our patient reported that he had sprayed herbicide in large quantities without wearing a mask. We analysed the BALF and herbicide by gas chromatography and diagnosed exogenous lipoid pneumonia caused by inhalation of herbicide. Clinicians should be aware of lipoid pneumonia, which may present as infectious pneumonia. PMID:27516888

  9. Forecasting residual herbicide concentrations in soil

    NASA Astrophysics Data System (ADS)

    McGrath, Gavan; Scanlan, Craig; van Zwieten, Lukas; Rose, Mick; Rose, Terry

    2016-04-01

    High concentrations of herbicides remaining in soil at the time of planting can adversely impact agricultural production and lead to off-site impacts in streams and groundwater. Being able to forecast the likelihood of residual concentrations at specific times in the future offers the potential to improve environmental and economic outcomes. Here we develop a solution for the full transient probability density function for herbicide concentrations in soil as a function of rainfall variability. Quasi-analytical solutions that account for rainfall seasonality are also demonstrated. In addition, new rapid and relatively cost-effective bioassays to quantify herbicide concentrations in near real-time, offers opportunities for data assimilation approaches to improve forecast risks.

  10. Selectable markers: antibiotic and herbicide resistance.

    PubMed

    Goodwin, Julia L; Pastori, Gabriela M; Davey, Michael R; Jones, Huw D

    2005-01-01

    The low efficiencies of most plant transformation methods necessitate the use of selectable marker genes to identify those cells that successfully integrate and express transferred DNA. Genes conferring resistance to various antibiotics or herbicides are commonly used in laboratory transformation research. They encode proteins that detoxify corresponding selection agents and allow the preferential growth of transformed cells. This chapter describes the application of two selection systems on the transformation of wheat. One is based on the nptII gene and corresponding aminoglycoside antibiotics, the other is based on the bar gene and corresponding glufosinate ammonium herbicides. PMID:15310922

  11. Quantifying vapor drift of dicamba herbicides applied to soybean.

    PubMed

    Egan, J Franklin; Mortensen, David A

    2012-05-01

    Recent advances in biotechnology have produced cultivars of corn, soybean, and cotton resistant to the synthetic-auxin herbicide dicamba. This technology will allow dicamba herbicides to be applied in new crops, at new periods in the growing season, and over greatly expanded areas, including postemergence applications in soybean. From past and current use in corn and small grains, dicamba vapor drift and subsequent crop injury to sensitive broadleaf crops has been a frequent problem. In the present study, the authors measured dicamba vapor drift in the field from postemergence applications to soybean using greenhouse-grown soybean as a bioassay system. They found that when the volatile dimethylamine formulation is applied, vapor drift could be detected at mean concentrations of 0.56 g acid equivalent dicamba/ha (0.1% of the applied rate) at 21 m away from a treated 18.3 × 18.3 m plot. Applying the diglycolamine formulation of dicamba reduced vapor drift by 94.0%. With the dimethylamine formulation, the extent and severity of vapor drift was significantly correlated with air temperature, indicating elevated risks if dimethylamine dicamba is applied early to midsummer in many growing regions. Additional research is needed to more fully understand the effects of vapor drift exposures to nontarget crops and wild plants. PMID:22362509

  12. Application of electrokinetic soil flushing to four herbicides: A comparison.

    PubMed

    Vieira Dos Santos, E; Souza, F; Saez, C; Cañizares, P; Lanza, M R V; Martinez-Huitle, C A; Rodrigo, M A

    2016-06-01

    In this work, four bench-scale plants containing soil spiked with four herbicides (2,4-Dichlorophenoxyacetic acid (2,4-D), oxyfluorfen, chlorsulfuron and atrazine) undergo treatment consisting of an electrokinetic soil flushing (EKSF). Results clearly demonstrate that efficiency of EKSF depends on the chemical characteristic of the pesticide used. The amount of pesticide collected in the anode well is more significant than that collected in the cathode wells, indicating that the electromigration is much more important than drainage by electro-osmotic flux for this application. After 15 d of treatment, the 2,4-D is the pesticide most efficiently removed (95% of removal), while chlorsulfuron is the pesticide more resilient to the treatment. Additionally, volatilization was found to be a process of the major significance in the application of electrokinetic techniques to soil polluted with herbicides and because of that it should always be taken into account in the future design of full-scale processes. PMID:27016816

  13. Mode of Action Studies on Nitrodiphenyl Ether Herbicides 1

    PubMed Central

    Bowyer, John R.; Hallahan, Beverly J.; Camilleri, Patrick; Howard, Joy

    1989-01-01

    The nitrodiphenyl ether herbicide 5-[2-chloro-4-(trifluoromethyl)phenoxy]-2-nitroacetophenone oxime-o-(acetic acid, methyl ester) (DPEI) induces light- and O2-dependent lipid peroxidation and chlorophyll (Chl) bleaching in the green alga Scenedesmus obliquus. Under conditions of O2-limitation, these effects are diminished by prometyne and 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), both inhibitors of photosynthetic electron transport. Mutants in which photosynthetic electron transport is blocked are also resistant to DPEI under conditions of O2-limitation. Light- and O2-dependent lipid peroxidation and Chl bleaching are also induced by 5-[2-chloro-4-(trifluoromethyl)phenoxy]-3-methoxyphthalide (DPEII), a diphenyl ether whose redox properties preclude reduction by photosystem I. However, these effects of DPEII are also inhibited by DCMU. Under conditions of high aeration, DCMU does not protect Scenedesmus cells from Chl bleaching induced by DPEI, but does protect against paraquat. DPEI, but not paraquat, induces tetrapyrrole formation in treated cells in the dark. This is also observed in a mutant lacking photosystem I but is suppressed under conditions likely to lead to O2 limitation. Our results indicate that, in contrast to paraquat, the role of photosynthetic electron transport in diphenyl ether toxicity in Scenedesmus is not to reduce the herbicide to a radical species which initiates lipid peroxidation. Its role is probably to maintain a sufficiently high O2 concentration, through water-splitting, in the algal suspension. PMID:16666600

  14. A biosensor for organoarsenical herbicides and growth promoters

    PubMed Central

    Chen, Jian; Sun, Samio; Li, Chen-Zhong; Zhu, Yong-Guan; Rosen, Barry P.

    2014-01-01

    The toxic metalloid arsenic is widely distributed in food, water, and soil. While inorganic arsenic enters the environment primarily from geochemical sources, methylarsenicals either result from microbial biotransformation of inorganic arsenic or are introduced anthropogenically. Methylarsenicals such as monosodium methylarsonic acid (MSMA) have been extensively utilized as herbicides, and aromatic arsenicals such as roxarsone (Rox) are used as growth promoters for poultry and swine. Organoarsenicals are degraded to inorganic arsenic. The toxicological effects of arsenicals depend on their oxidation state, chemical composition, and bioavailability. Here we report that the active forms are the trivalent arsenic-containing species. We constructed a whole-cell biosensor utilizing a modified ArsR repressor that is highly selective toward trivalent methyl and aromatic arsenicals, with essentially no response to inorganic arsenic. The biosensor was adapted for in vitro detection of organoarsenicals using fluorescence anisotropy of ArsR-DNA interactions. It detects bacterial biomethylation of inorganic arsenite both in vivo and in vitro with detection limits of 10−7 M and linearity to 10−6 M for phenylarsenite and 5×10−6 M for methylarsenite. The biosensor detects reduced forms of MSMA and roxarsone and offers a practical, low cost method for detecting activate forms and breakdown products of organoarsenical herbicides and growth promoters. PMID:24359149

  15. Determination of antagonism between cyhalofop-butyl and other rice (Oryza sativa) herbicides in barnyardgrass (Echinochloa crus-galli).

    PubMed

    Ottis, Brian V; Mattice, John D; Talbert, Ronald E

    2005-05-18

    Herbicide antagonism is defined as the reduction of control of certain weeds as the result of applying mixtures of two or more herbicides. Cyhalofop-butyl, a graminicide used for postemergence grass weed control in rice, is antagonized by some rice herbicides when applied simultaneously. The result of this type of antagonism usually results in decreased control of grass weeds. Research has shown that herbicide antagonism between graminicides and other herbicides may be caused by different mechanisms as the result of activity of the tank-mix partner. Using HPLC, the objective of this experiment was to analyze the fate of cyhalofop-butyl in barnyardgrass tissue when applied alone and in combination with halosulfuron, propanil, or triclopyr. Results indicated that absorption of cyhalofop-butyl and hydrolysis to its phytotoxic metabolite, cyhalofop-acid, was rapid and that halosulfuron and triclopyr had no effect. Because of a likely interaction of propanil with an apoplastic esterase enzyme, increased levels of cyhalofop-butyl and cyhalofop-acid were detected in barnyardgrass tissue, indicating that cyhalofop-butyl metabolism was hindered by propanil. PMID:15884840

  16. Mineralization of s-triazine herbicides by a newly isolated Nocardioides species strain DN36.

    PubMed

    Satsuma, Koji

    2010-05-01

    A novel s-triazine-mineralizing bacterium-Nocardioides sp. strain DN36-was isolated from paddy field soil treated with ring-U-(14)C-labeled simetryn ([(14)C]simetryn) in a model paddy ecosystem (microcosm). In a tenfold-diluted R2A medium, strain DN36 liberated (14)CO(2) from not only [(14)C]simetryn but also three ring-U-(14)C-labeled s-triazines: atrazine, simazine, and propazine. We found that DN36 mineralized ring-U-(14)C-cyanuric acid added as an initial substrate, indicating that the bacterium mineralized s-triazine herbicides via a common metabolite, namely, cyanuric acid. Strain DN36 harbored a set of genes encoding previously reported s-triazine-degrading enzymes (TrzN-AtzB-AtzC), and it also transformed ametryn, prometryn, dimethametryn, atraton, simeton, and prometon. The findings suggest that strain DN36 can mineralize a diverse range of s-triazine herbicides. To our knowledge, strain DN36 is the first Nocardioides strain that can individually mineralize s-triazine herbicides via the ring cleavage of cyanuric acid. Further, DN36 could not grow on cyanuric acid, and the degradation seemed to occur cometabolically. PMID:20169342

  17. A Rapid and Simple Bioassay Method for Herbicide Detection

    PubMed Central

    Li, Xiu-Qing; Ng, Alan; King, Russell; Durnford, Dion G.

    2008-01-01

    Chlamydomonas reinhardtii, a unicellular green alga, has been used in bioassay detection of a variety of toxic compounds such as pesticides and toxic metals, but mainly using liquid culture systems. In this study, an algal lawn—agar system for semi-quantitative bioassay of herbicidal activities has been developed. Sixteen different herbicides belonging to 11 different categories were applied to paper disks and placed on green alga lawns in Petri dishes. Presence of herbicide activities was indicated by clearing zones around the paper disks on the lawn 2–3 days after application. The different groups of herbicides induced clearing zones of variable size that depended on the amount, mode of action, and chemical properties of the herbicides applied to the paper disks. This simple, paper-disk-algal system may be used to detect the presence of herbicides in water samples and act as a quick and inexpensive semi-quantitative screening for assessing herbicide contamination. PMID:19578512

  18. Molecular and biophysical analysis of herbicide-resistant mutants of Chlamydomonas reinhardtii: structure-function relationship of the photosystem II D1 polypeptide.

    PubMed Central

    Erickson, J M; Pfister, K; Rahire, M; Togasaki, R K; Mets, L; Rochaix, J D

    1989-01-01

    Plants and green algae can develop resistance to herbicides that block photosynthesis by competing with quinones in binding to the chloroplast photosystem II (PSII) D1 polypeptide. Because numerous herbicide-resistant mutants of Chlamydomonas reinhardtii with different patterns of resistance to such herbicides are readily isolated, this system provides a powerful tool for examining the interactions of herbicides and endogenous quinones with the photosynthetic membrane, and for studying the structure-function relationship of the D1 protein with respect to PSII electron transfer. Here we report the results of DNA sequence analysis of the D1 gene from four mutants not previously characterized at the molecular level, the correlation of changes in specific amino acid residues of the D1 protein with levels of resistance to the herbicides atrizine, diuron, and bromacil, and the kinetics of fluorescence decay for each mutant, which show that changes at two different amino acid residues dramatically slow PSII electron transfer. Our analyses, which identify a region of 57 amino acids of the D1 polypeptide involved in herbicide binding and which define a D1 binding niche for the second quinone acceptor, QB of PSII, provide a strong basis of support for structural and functional models of the PSII reaction center. PMID:2535507

  19. Enantioselective stable isotope analysis (ESIA) of polar Herbicides

    NASA Astrophysics Data System (ADS)

    Maier, Michael; Qiu, Shiran; Elsner, Martin

    2013-04-01

    The complexity of aquatic systems makes it challenging to assess the environmental fate of chiral micropolutants. As an example, chiral herbicides are frequently detected in the environment (Buser and Muller, 1998); however, hydrological data is needed to determine their degradability from concentration measurements. Otherwise declining concentrations cannot unequivocally be attributed to degradation, but could also be caused by dilution effects. In contrast, isotope ratios or enantiomeric ratios are elegant alternatives that are independent of dilution and can even deliver insights into reaction mechanisms. To combine the advantages of both approaches we developed an enatioselective stable isotope analysis (ESIA) method to investigate the fate of the chiral herbicides 4-CPP ((RS)-2-(4-chlorophenoxy)-propionic acid), mecoprop (2-(4-Chloro-2-methylphenoxy)-propionic acid) and dichlorprop (2-(2,4-Dichlorophenoxy)-propionic acid). After testing the applicable concentration range of the method, enantioselective isotope fractionation was investigated by microbial degradation using dichlorprop as a model compound. The method uses enantioselective gas-chromatography (GC) to separate enantiomers. Subsequently samples are combusted online to CO2 and carbon isotope ratios are determined for each enantiomer by isotope-ratio-mass-spectrometry (IRMS). Because the analytes contain a polar carboxyl-group, samples were derivatised prior to GC-IRMS analysis with methanolic BF3 solution. Precise carbon isotope analysis (2σ ≤0.5‰) was achieved with a high sensitivity of ≥ 7 ng C that is needed on column for one analysis. Microbial degradation of the model compound dichlorprop was conducted with Delftia acidovorans MC1 and pronounced enantiomer fractionation, but no isotope fractionation was detected. The absence of isotope fractionation can be explained by two scenarios: either the degrading enzyme has no isotopic preference, or another step in the reaction without an isotopic

  20. Response of Soybean to Halosulfuron Herbicide

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Recently, halosulfuron injury in soybean through off-target movement of halosulfuron when applied to rice fields has been reported. Sulfonylurea-tolerant (ST) soybean varieties have enhanced tolerance for sulfonylurea herbicides and might provide an option of mitigating injury to soybean from halosu...

  1. Managing weeds in potato rotations without herbicides

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Managing weeds without herbicides requires an integration of methods and strategies and a change in how weeds are perceived. Weeds should be managed in a holistic, intentional and proactive manner. Successful weed management in organic systems attempts to understand the interactions between the crop...

  2. Mustard meal as an organic herbicide

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Mustard meal (MM) is phytotoxic and a potential pre-emergent and preplant-incorporated organic herbicide for controlling germinating and emerging weed seedlings: unfortunately, MM may also adversely impact seedling survival of certain direct-seeded vegetable crops. Field research was conducted in s...

  3. Herbicide Resistance in Datura innoxia1

    PubMed Central

    Saxena, Praveen K.; King, John

    1988-01-01

    Cells resistant to the sulfonylurea herbicides chlorsulfuron and sulfometuron methyl were isolated from a predominantly haploid cell suspension culture of Datura innoxia P. Mill. Exponentially growing cell colonies (aggregates of about 40 cells) were mutagenized with ethyl methane sulfonate, subcultured for 10 days to allow growth recovery and plated on a medium containing either chlorsulfuron or sulfometuron methyl at a concentration (10−8 molar) which killed wild type cells. Surviving clones were picked up after 3 to 4 weeks, further proliferated as callus or cell suspension cultures, and tested for their resistance to both the sulfonylureas and imidazolinones, a chemically different class of herbicides. The variants were stable and showed high (100- to 1000-fold) resistance to the sulfonylureas. While some also exhibited cross resistance to imidazolinones, others showed no cross-resistance at all or, as in one case, greater sensitivity than wild type cells to the imidazolinones. Both classes of herbicides tested inhibited acetolactate synthase activity isolated from wild type cells. The acetolactate synthase of the resistant variants, however, was found to be resistant to the sulfonylureas and also to the imidazolinone(s) in those cells showing cross-resistance to the latter. The lack of cross-resistance observed in some cases provides evidence that the two groups of herbicides have slightly different sites on the acetolactate synthase molecule. Images Fig. 2 PMID:16666001

  4. Herbicide options for suppressing bermudagrass in sugarcane

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bermudagrass is a problematic weed in Louisiana sugarcane. The most effective herbicide options are limited to the fallow period prior to planting. Frequently, efforts to eliminate bermudagrass from fields during the fallow season are unsuccessful. This subjects newly planted sugarcane to competitio...

  5. Herbicide drift affects plant and arthropod communities

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Field edges, old fields, and other semi-natural habitats in agricultural landscapes support diverse plant communities that help sustain pollinators, predators, and other beneficial arthropods. These plant and arthropod communities may be at persistent ecotoxicological risk from herbicides applied to...

  6. Herbicides as probes in plant biology

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Herbicides are small molecules that inhibit specific molecular target sites within plant biochemical pathways and/or physiological processes. Inhibition of these sites often has catastrophic consequences that are lethal to plants. The affinity of these compounds for their respective target sites ...

  7. Kudzu response to foliar applied herbicides

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Chemical control is presently the most cost-effective means to control kudzu, however, many of the herbicides labeled for kudzu control have substantial non-target toxicity, poor selectivity, high cost, long soil persistence, high soil mobility and / or high use rates. The present study evaluated ot...

  8. Herbicides as stimulators regulators and ripeners

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The use of low doses of herbicide as plant growth regulators to increase sugar concentrations (ripen) in sugarcane prior to harvest plays an important role in the profitable and sustainable production of sugarcane in the U.S. as well as in other sugarcane industries around the world. Several studies...

  9. The 1975 Insecticide, Herbicide, Fungicide Quick Guide.

    ERIC Educational Resources Information Center

    Page, Bill G.; Thomson, W. T.

    This is a quick guide for choosing a chemical to use to control a certain pest on a specific crop. Information in the book was obtained from manufacturers' labels and from the USDA and FDA pesticide summary. The book is divided into four parts: (1) insecticides, (2) herbicides, (3) fungicides, and (4) conversion tables. Each of the first three…

  10. Herbicide dissipation from low density polyethylene mulch

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Field and laboratory studies were conducted to examine herbicide dissipation when applied to low density polyethylene (LDPE) mulch for dry scenarios vs. washing off with water. In field studies, halosulfuron, paraquat, carfentrazone, glyphosate, and flumioxazin were applied to black 1.25-mil LDPE at...

  11. Ammonium pelargonate as a potential organic herbicide

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Weed control is a serious concern for commercial vegetable producers because of the limited number of herbicides available for this group of minor crops and the potential for crop injury. Organic producers of vegetables have an even greater challenge since their weed control tools are limited to cu...

  12. ENVIRONMENTAL AND TOXICOLOGICAL PROPERTIES OF HERBICIDES

    EPA Science Inventory

    Herbicides comprise over 75% of all the agricultural pesticide use in the United States. This amounts to over 500 million pounds of active ingredients applied each year. The US EPA has the responsibility to register these products and label them for use such that unintended effec...

  13. Cellular membranes, the sites for the antifungal activity of the herbicide sethoxydim.

    PubMed

    Pakdaman, B S; Goltapeh, E Mohammadi; Sepehrifar, R; Pouriesa, M; Fard, M Rahimi; Moradi, F; Modarres, S A M

    2007-08-01

    The fungicidal effect of sethoxydim on the canola (Brassica napus var. Olifera) white stem rot pathogen (Sclerotinia sclerotiorum) encouraged us to conduct a series of studies on the mechanism of the antifungal activity of this herbicide commonly applied in Iranian fields under canola cultivation. Present preliminary studies on the changes in the level of Malondialdehyde (MDA) as the main product generated through peroxidation of polyunsaturated fatty acids indicated the disintegration of the fungal bilayer of plasma membrane as the result of the herbicidal treatment. Also, it was demonstrated that the amount of hydrogen peroxide in the treated samples was higher than the control samples with no herbicidal treatment. Therefore, our present results confirm the disintegration of the plasma membrane as one of the mechanism for the antifungal impact of sethoxydim. As with weed plants, the phytotoxic impact of this herbicide has been attributed to the inhibition of the first enzyme in the lipid biosynthesis pathway, acetyl-CoA carboxylase, therefore, it would be very interesting to study on this subject and the relations between the sensitivity of different fungi and their DNA and protein sequences of acetyl-CoA carboxylase. PMID:19070118

  14. Controlled release of water-soluble herbicides

    SciTech Connect

    Riggle, B.D.

    1985-01-01

    Pine kraft lignin was used to control the release of metribuzin (4-amino-6-tert-butyl-3-(methylthio)-as-triazin-5(4H)-one) and alachlor (2-chloro-2',6'-diethyl-N-methoxy-methyl acetanalide). Soil thin layer chromatography (TLC) analysis using /sup 14/C-metribuzin and /sup 14/C-alachlor demonstrated that NB-5203-58 series and PC940 series kraft lignins could retard the mobility of both herbicides after multiple soil TLC plate developments with water. Soil column chromatography analysis demonstrated that PC940C could retard the mobility of both herbicides after soil column water leaching by positioning the herbicides in the top portion of the soil column where the PC940C-herbicide mixture had been applied. There was a concentration effect where, as more PC940C was used, more /sup 14/C-labelled herbicide was retained in the top portion of the soil columns. Soil column chromatography and soil TLC plate analysis demonstrated that /sup 3/H-PC940C was immobile. Finally, PC940C significantly reduced metribuzin related phytotoxicity to field and greenhouse grown soybeans (Glycine max (L.) Merr.) which had been treated with PC940C rates of 0.77 and 1.15 L/ha and metribuzin rates of 0.42 and 0.84 kg/ha. The results for /sup 14/C-metribuzin and /sup 14/C-alachlor as well as the reduction in metribuzin related phytotoxicity to soybeans suggests that PC940C can effectively control the release of metribuzin and alachlor.

  15. Acute toxicity of Roundup® herbicide to three life stages of the freshwater shrimp Caridina nilotica (Decapoda: Atyidae)

    NASA Astrophysics Data System (ADS)

    Mensah, P. K.; Muller, W. J.; Palmer, C. G.

    Glyphosate based herbicides, including Roundup®, are frequently used in the chemical control of weeds and invading alien plant species in South Africa. These herbicides ultimately get into water courses directly or indirectly through processes such as drifting, leaching, surface runoff and foliar spray of aquatic nuisance plants. Despite their widespread use, no water quality guideline exists to protect indigenous South African freshwater organisms from the toxic effects of these herbicides. The toxicity of the herbicide Roundup® was assessed using three different life stages of the freshwater shrimp Caridina nilotica, a prevalent species in South African freshwater ecosystems. Neonate (<7 days post hatching (dph)), juvenile (>7 dph and <20 dph) and adult (>40 dph) shrimps were exposed to varying concentrations (1.5-50 mg/L acid equivalence (a.e.)) of the herbicide in 48 and 96 h acute toxicity tests in order to determine the most sensitive life-stage. The results showed neonates to be more sensitive to Roundup® than both juveniles and adults with mean 96 h LC 50 values of 2.5, 7.0 and 25.3 mg/L a.e. respectively. The estimated 96 h LC 50 of neonates is much lower than the application rate (20-30 mg/L a.e.), although the application’s impact will depend on the dilution rate of the applied concentration in the environment. All three life-stages of unexposed animals exhibited active and coordinated movement but exposed shrimps were erratic and slow in their movements, with neonates showing most of these behavioral irregularities. This study shows that low levels of the herbicide Roundup® may adversely affect C. nilotica health and survival. Thus, the herbicide should be carefully managed to minimize any negative impact on non-target freshwater organisms.

  16. Multiple Herbicide Resistance in Lolium multiflorum and Identification of Conserved Regulatory Elements of Herbicide Resistance Genes.

    PubMed

    Mahmood, Khalid; Mathiassen, Solvejg K; Kristensen, Michael; Kudsk, Per

    2016-01-01

    Herbicide resistance is a ubiquitous challenge to herbicide sustainability and a looming threat to control weeds in crops. Recently four genes were found constituently over-expressed in herbicide resistant individuals of Lolium rigidum, a close relative of Lolium multiflorum. These include two cytochrome P450s, one nitronate monooxygenase and one glycosyl-transferase. Higher expressions of these four herbicide metabolism related (HMR) genes were also observed after herbicides exposure in the gene expression databases, indicating them as reliable markers. In order to get an overview of herbicidal resistance status of L. multiflorum L, 19 field populations were collected. Among these populations, four populations were found to be resistant to acetolactate synthase (ALS) inhibitors while three exhibited resistance to acetyl-CoA carboxylase (ACCase) inhibitors in our initial screening and dose response study. The genotyping showed the presence of mutations Trp-574-Leu and Ile-2041-Asn in ALS and ACCase, respectively, and qPCR experiments revealed the enhanced expression of HMR genes in individuals of certain resistant populations. Moreover, co-expression networks and promoter analyses of HMR genes in O. sativa and A. thaliana resulted in the identification of a cis-regulatory motif and zinc finger transcription factors. The identified transcription factors were highly expressed similar to HMR genes in response to xenobiotics whereas the identified motif is known to play a vital role in coping with environmental stresses and maintaining genome stability. Overall, our findings provide an important step forward toward a better understanding of metabolism-based herbicide resistance that can be utilized to devise novel strategies of weed management. PMID:27547209

  17. Multiple Herbicide Resistance in Lolium multiflorum and Identification of Conserved Regulatory Elements of Herbicide Resistance Genes

    PubMed Central

    Mahmood, Khalid; Mathiassen, Solvejg K.; Kristensen, Michael; Kudsk, Per

    2016-01-01

    Herbicide resistance is a ubiquitous challenge to herbicide sustainability and a looming threat to control weeds in crops. Recently four genes were found constituently over-expressed in herbicide resistant individuals of Lolium rigidum, a close relative of Lolium multiflorum. These include two cytochrome P450s, one nitronate monooxygenase and one glycosyl-transferase. Higher expressions of these four herbicide metabolism related (HMR) genes were also observed after herbicides exposure in the gene expression databases, indicating them as reliable markers. In order to get an overview of herbicidal resistance status of L. multiflorum L, 19 field populations were collected. Among these populations, four populations were found to be resistant to acetolactate synthase (ALS) inhibitors while three exhibited resistance to acetyl-CoA carboxylase (ACCase) inhibitors in our initial screening and dose response study. The genotyping showed the presence of mutations Trp-574-Leu and Ile-2041-Asn in ALS and ACCase, respectively, and qPCR experiments revealed the enhanced expression of HMR genes in individuals of certain resistant populations. Moreover, co-expression networks and promoter analyses of HMR genes in O. sativa and A. thaliana resulted in the identification of a cis-regulatory motif and zinc finger transcription factors. The identified transcription factors were highly expressed similar to HMR genes in response to xenobiotics whereas the identified motif is known to play a vital role in coping with environmental stresses and maintaining genome stability. Overall, our findings provide an important step forward toward a better understanding of metabolism-based herbicide resistance that can be utilized to devise novel strategies of weed management. PMID:27547209

  18. Determination of kinetic and equilibrium regimes in the operation of polar organic chemical integrative samplers. Application to the passive sampling of the polar herbicides in aquatic environments.

    PubMed

    Mazzella, Nicolas; Dubernet, Jean-François; Delmas, François

    2007-06-22

    This work set out the laboratory calibration of the passive samplers such as polar organic chemical integrative samplers (POCISs) which preconcentrate hydrophilic organic contaminants in aqueous medium. We compared the two different configurations available (i.e. pesticide and pharmaceutical POCISs) for sampling different classes of herbicides representative of a wide range of polarity (5.34>of=log Kow>or=-1.70). The results showed that pharmaceutical configuration was probably more convenient for sampling basic, neutral or acidic herbicides. Afterward, we performed a kinetic study with the pharmaceutical POCIS only. This calibration revealed linear and integrative uptakes of several herbicides for 21 days. For some compounds like sulcotrione, mesotrione, deisopropylatrazine (DIA) and deethylatrazine (DEA), the linear uptake model was only valid for 10 days. Lastly, we observed an increase of the sampling rates with the hydrophobicity of the herbicides. PMID:17439817

  19. Comparison of extraction solvents and conditions for herbicide residues in milled rice with liquid chromatography-diode array detection analysis (LC-DAD).

    PubMed

    Niell, S; Pareja, L; Geis Asteggiante, L; Cesio, M V; Heinzen, H

    2010-02-01

    Different extraction procedures and clean-up methods were compared in order to develop a sample preparation procedure for the multi-residue analysis of six post-emergence herbicides (metsulfuron methyl, bensulfuron methyl, pyrazosulfuron ethyl, bentazone, bispyribac sodium and cyhalofop butyl) in rice grains followed by liquid chromatography-diode array detection (LC-DAD). Optimum results were obtained dispersing milled rice grain in water, followed by the addition of 1% acetic acid in acetonitrile, MgSO(4) and sodium acetate as a modification of the quick, easy, cheap, effective, rugged and safe (QuEChERS) method but no primary and secondary amine (PSA) sorbent was added due to the acidic nature of the herbicides. The method was further expanded to other post-emergence herbicides (quinclorac, clomazone and propanil). Except for quinclorac, which cannot be analysed with this method, the recoveries of the other eight herbicides were in the range 73-111%, with relative standard deviations lower than 12%. Limits of detection (LODs) ranged from 0.03 to 0.08 mg kg(-1). A single analyst can extract twelve samples in 4 h. The method presented here allows the simultaneous residue determination of the most common post-emergence herbicides employed in cultivating rice. It is simple, rapid, sensitive, and can be applied routinely to polished rice grain herbicide residue analysis. PMID:20013445

  20. Herbicide and pesticide occurrence in the soils of children's playgrounds in Sarajevo, Bosnia and Herzegovina.

    PubMed

    Sapcanin, Aida; Cakal, Mirsada; Imamovic, Belma; Salihovic, Mirsada; Pehlic, Ekrem; Jacimovic, Zeljko; Jancan, Gordan

    2016-08-01

    Pesticide pollution in Sarajevo public playgrounds is an important health and environmental issue, and the lack of information about it is causing concerns amongst the general population as well as researchers. Since children are in direct contact with surface soils on children's playgrounds, such soils should be much more carefully examined. Furthermore, herbicides and pesticides get transmitted from soil surfaces brought from outside the urban areas, or they get dispersed following their direct applications in urban areas. Infants' and children's health can be directly affected by polluted soils because of the inherent toxicity and widespread use of the different pesticides in urban environments such as playgrounds. In addition to that, the presence of chromated copper arsenate (CCA) wood preservative pesticide found as soil pollutant in playing equipment was also documented. Soil samples from playgrounds were collected and analyzed for triazines, carbamates, dithiocarbamates, phenolic herbicides and organochlorine pesticides. Samples for the determination of heavy metals Cu, Cr and As were prepared by microwave-assisted acid digestion, and the findings were determined by using an inductively coupled plasma optical emission spectrometer. Triazines, carbamates, dithiocarbamates, chlorphenoxy compounds, phenolic herbicides, organochlorine pesticides and organotin compounds were detected in playground soils and their determined concentrations (mg/kg) were respectively found as follows: <0.005, <0.05, <0.5, < 0.4, <0.1, <0.001 and <0.004. The determined contents (mg/kg) of Cu, Cr and As were in the ranges from 16.77 to 80.21, from 7.14 to 15.45 and from 3.31 to 4.43, respectively. Our preliminary results raise concerns about potential adverse effects of herbicides and pesticides on human health, which strengthens the case for a more preventative and protective approach to the uncontrolled presence of herbicides and pesticides in Sarajevo's playground soils. PMID

  1. Synthesis and herbicidal activity evaluation of novel α-amino phosphonate derivatives containing a uracil moiety.

    PubMed

    Che, Jian-yi; Xu, Xiao-yun; Tang, Zi-long; Gu, Yu-cheng; Shi, De-qing

    2016-02-15

    A series of novel α-amino phosphonate derivatives containing a uracil moiety 3a-3l were designed and synthesized by a Lewis acid (magnesium perchlorate) catalyzed the Kabachnik-Fields reaction. The bioassays {in vitro, in vivo [Glass House 1 (GH1) and Glass House 2 (GH2)]} showed that most of compounds 3 exhibited excellent and selective herbicidal activities; for example, in GH1 test, compounds 3b, 3d, 3f, 3h and 3j showed excellent and wide spectrum herbicidal activities at the dose of 1000 g/ha, and compounds 3b and 3j exhibited 100% inhibition activities against the four plants in both post- and pre-emergence treatments. Moreover, most of compounds 3 showed higher inhibition against Amaranthus retroflexus and Digitaria sanguinalis than Glyphosate did in pre-emergence treatment. In GH2 test, the four compounds (3b, 3d, 3h and 3j) exhibited 100% inhibition against Solanum nigrum, Amaranthus retroflexus and Ipomoea hederacea in post-emergence treatment and displayed 100% inhibition against Solanum nigrum, Amaranthus retroflexus in pre-emergence treatment at the rate of 250 g/ha, and compound 3b showed the best and broad spectrum herbicidal activities against the six test plants. However, the four compounds displayed weaker herbicidal activities against Lolium perenne and Echinochloa crus-galli than the other four plants at the rate of 250 g/ha in both pre- and post-emergence treatments. So, compounds 3 can be used as a lead compound for further structure optimization for developing potential selective herbicidal agent. Their preliminary structure-activity relationships were also investigated. PMID:26786699

  2. Synonymous mutation gene design to overexpress ACCase in creeping bentgrass to obtain resistance to ACCase-inhibiting herbicides.

    PubMed

    Heckart, Douglas L; Schwartz, Brian M; Raymer, Paul L; Parrott, Wayne A

    2016-08-01

    Overexpression of a native gene can cause expression of both introduced and native genes to be silenced by posttranscriptional gene silencing (PTGS) mechanisms. PTGS mechanisms rely on sequence identity between the transgene and native genes; therefore, designing genes with mutations that do not cause amino acid changes, known as synonymous mutations, may avoid PTGS. For proof of concept, the sequence of acetyl-coA carboxylase (ACCase) from creeping bentgrass (Agrostis stolonifera L.) was altered with synonymous mutations. A native bentgrass ACCase was cloned and used as a template for the modified gene. Wild-type (WT) and modified genes were further modified with a non-synonymous mutation, coding for an isoleucine to leucine substitution at position 1781, known to confer resistance to ACCase-inhibiting herbicides. Five-hundred calli of creeping bentgrass 'Penn A-4' were inoculated with Agrobacterium containing either the WT or modified genes, with or without the herbicide-resistance mutation. Six herbicide-resistant-transgenic events containing the modified gene with the 1781 mutation were obtained. Transcription of the modified ACCase was confirmed in transgenic plants, showing that gene-silencing mechanisms were avoided. Transgenic plants were confirmed to be resistant to the ACCase-inhibiting herbicide, sethoxydim, providing evidence that the modified gene was functional. The result is a novel herbicide-resistance trait and shows that overexpression of a native enzyme with a gene designed with synonymous mutations is possible. PMID:27116460

  3. Inheritance and molecular characterization of broad range tolerance to herbicides targeting acetohydroxyacid synthase in sunflower.

    PubMed

    Sala, Carlos A; Bulos, Mariano

    2012-02-01

    Ahasl1 is a multilallelic locus where all the induced and natural mutations for herbicide tolerance were described thus far in sunflower (Helianthus annuus L.). The allele Ahasl1-1 confers moderate tolerance to imidazolinone (IMI), Ahasl1-2, and Ahasl1-3 provides high levels of tolerance solely to sulfonylurea (SU) and IMI, respectively. An Argentinean wild sunflower population showing plants with high level of tolerance to either an IMI and a SU herbicide was discovered and used to develop an inbred line designated RW-B. The objectives of this work were to determine the relative level and pattern of cross-tolerance to different AHAS-inhibiting herbicides, the mode of inheritance, and the molecular basis of herbicide tolerance in this line. Slight or no symptoms observed after application of different herbicides indicated that RW-B possesses a completely new pattern of tolerance to AHAS-inhibiting herbicides in sunflower. Biomass response to increasing doses of metsulfuron or imazapyr demonstrated a higher level of tolerance in RW-B with respect to Ahasl1-1/Ahasl1-1 and Ahasl1-2/Ahasl1-2 lines. On the basis of genetic analyses and cosegregation test, it was concluded that tolerance to imazapyr in the original population is inherited as a single, partially dominant nuclear gene and that this gene is controlling the tolerance to four different AHAS-inhibiting herbicides. Pseudo-allelism test permitted us to conclude that the tolerant allele present in RW-B is an allelic variant of Ahasl1-1 and was designated as Ahasl1-4. Nucleotide and deduced amino acid sequence indicated that the Ahasl1-4 allele sequence of RW-B has a leucine codon (TTG) at position 574 (relative to the Arabidopsis thaliana AHAS sequence), whereas the enzyme from susceptible lines has a tryptophan residue (TGG) at this position. The utilization of this new allele in the framework of weed control and crop rotation is discussed. PMID:21959907

  4. Maize, switchgrass, and ponderosa pine biochar added to soil increased herbicide sorption and decreased herbicide efficacy.

    PubMed

    Clay, Sharon A; Krack, Kaitlynn K; Bruggeman, Stephanie A; Papiernik, Sharon; Schumacher, Thomas E

    2016-08-01

    Biochar, a by-product of pyrolysis made from a wide array of plant biomass when producing biofuels, is a proposed soil amendment to improve soil health. This study measured herbicide sorption and efficacy when soils were treated with low (1% w/w) or high (10% w/w) amounts of biochar manufactured from different feedstocks [maize (Zea mays) stover, switchgrass (Panicum vigatum), and ponderosa pine (Pinus ponderosa)], and treated with different post-processing techniques. Twenty-four hour batch equilibration measured sorption of (14)C-labelled atrazine or 2,4-D to two soil types with and without biochar amendments. Herbicide efficacy was measured with and without biochar using speed of seed germination tests of sensitive species. Biochar amended soils sorbed more herbicide than untreated soils, with major differences due to biochar application rate but minor differences due to biochar type or post-process handling technique. Biochar presence increased the speed of seed germination compared with herbicide alone addition. These data indicate that biochar addition to soil can increase herbicide sorption and reduce efficacy. Evaluation for site-specific biochar applications may be warranted to obtain maximal benefits without compromising other agronomic practices. PMID:27153402

  5. Isolation and characterization of Bradyrhizobium sp. SR1 degrading two β-triketone herbicides.

    PubMed

    Romdhane, Sana; Devers-Lamrani, Marion; Martin-Laurent, Fabrice; Calvayrac, Christophe; Rocaboy-Faquet, Emilie; Riboul, David; Cooper, Jean-François; Barthelmebs, Lise

    2016-03-01

    In this study, a bacterial strain able to use sulcotrione, a β-triketone herbicide, as sole source of carbon and energy was isolated from soil samples previously treated with this herbicide. Phylogenetic study based on16S rRNA gene sequence showed that the isolate has 100 % of similarity with several Bradyrhizobium and was accordingly designated as Bradyrhizobium sp. SR1. Plasmid profiling revealed the presence of a large plasmid (>50 kb) in SR1 not cured under nonselective conditions. Its transfer to Escherichia coli by electroporation failed to induce β-triketone degrading capacity, suggesting that degrading genes possibly located on this plasmid cannot be expressed in E. coli or that they are not plasmid borne. The evaluation of the SR1 ability to degrade various synthetic (mesotrione and tembotrione) and natural (leptospermone) triketones showed that this strain was also able to degrade mesotrione. Although SR1 was able to entirely dissipate both herbicides, degradation rate of sulcotrione was ten times higher than that of mesotrione, showing a greater affinity of degrading-enzyme system to sulcotrione. Degradation pathway of sulcotrione involved the formation of 2-chloro-4-mesylbenzoic acid (CMBA), previously identified in sulcotrione degradation, and of a new metabolite identified as hydroxy-sulcotrione. Mesotrione degradation pathway leads to the accumulation of 4-methylsulfonyl-2-nitrobenzoic acid (MNBA) and 2-amino-4 methylsulfonylbenzoic acid (AMBA), two well-known metabolites of this herbicide. Along with the dissipation of β-triketones, one could observe the decrease in 4-hydroxyphenylpyruvate dioxygenase (HPPD) inhibition, indicating that toxicity was due to parent molecules, and not to the formed metabolites. This is the first report of the isolation of bacterial strain able to transform two β-triketones. PMID:25903192

  6. Herbicide Metabolites in Surface Water and Groundwater: Introduction and Overview

    USGS Publications Warehouse

    Thurman, E.M.; Meyer, M.T.

    1996-01-01

    Several future research topics for herbicide metabolites in surface and ground water are outlined in this chapter. They are herbicide usage, chemical analysis of metabolites, and fate and transport of metabolites in surface and ground water. These three ideas follow the themes in this book, which are the summary of a symposium of the American Chemical Society on herbicide metabolites in surface and ground water. First, geographic information systems allow the spatial distribution of herbicide-use data to be combined with geochemical information on fate and transport of herbicides. Next these two types of information are useful in predicting the kinds of metabolites present and their probable distribution in surface and ground water. Finally, methods development efforts may be focused on these specific target analytes. This chapter discusses these three concepts and provides an introduction to this book on the analysis, chemistry, and fate and transport of herbicide metabolites in surface and ground water.

  7. Adsorption of herbicides using activated carbons

    SciTech Connect

    Derbyshire, F.; Jagtoyen, M.; Lafferty, C.; Kimber, G.

    1996-12-31

    This paper describes the results of research in which novel activated carbons have been examined for their efficacy in water treatment and, specifically, for the adsorption of a common herbicide and wood preservative, sodium pentachlorophenolate. To place this work in context, the introduction will discuss first some of the considerations of using activated carbons for water treatment, and then certain aspects of the authors research that has led to this particular topic.

  8. Phytotoxicity of Delayed Applications of Dinitroaniline Herbicides in Strip-Tillage Peanut Production

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dinitroaniline herbicides are typically applied preplant incorporated or preemergence (PRE) immediately after seeding peanut. Situations frequently arise where dinitroaniline herbicides are not applied in a timely manner in strip-tillage peanut production. In these cases, dinitroaniline herbicides...

  9. Phytotoxicity of four photosystem II herbicides to tropical seagrasses.

    PubMed

    Flores, Florita; Collier, Catherine J; Mercurio, Philip; Negri, Andrew P

    2013-01-01

    Coastal waters of the Great Barrier Reef (GBR) are contaminated with agricultural pesticides, including the photosystem II (PSII) herbicides which are the most frequently detected at the highest concentrations. Designed to control weeds, these herbicides are equally potent towards non-target marine species, and the close proximity of seagrass meadows to flood plumes has raised concerns that seagrasses may be the species most threatened by herbicides from runoff. While previous work has identified effects of PSII herbicides on the photophysiology, growth and mortality in seagrass, there is little comparative quantitative toxicity data for seagrass. Here we applied standard ecotoxicology protocols to quantify the concentrations of four priority PSII herbicides that inhibit photochemistry by 10, 20 and 50% (IC10, IC20 and IC50) over 72 h in two common seagrass species from the GBR lagoon. The photosystems of seagrasses Zosteramuelleri and Haloduleuninervis were shown to be generally more sensitive to the PSII herbicides Diuron, Atrazine, Hexazinone and Tebuthiuron than corals and tropical microalgae. The herbicides caused rapid inhibition of effective quantum yield (∆F/F m '), indicating reduced photosynthesis and maximum effective yields (Fv/Fm ) corresponding to chronic damage to PSII. The PSII herbicide concentrations which affected photosynthesis have been exceeded in the GBR lagoon and all of the herbicides inhibited photosynthesis at concentrations lower than current marine park guidelines. There is a strong likelihood that the impacts of light limitation from flood plumes and reduced photosynthesis from PSII herbicides exported in the same waters would combine to affect seagrass productivity. Given that PSII herbicides have been demonstrated to affect seagrass at environmental concentrations, we suggest that revision of environmental guidelines and further efforts to reduce PSII herbicide concentrations in floodwaters may both help protect seagrass meadows of

  10. Phytotoxicity of Four Photosystem II Herbicides to Tropical Seagrasses

    PubMed Central

    Flores, Florita; Collier, Catherine J.; Mercurio, Philip; Negri, Andrew P.

    2013-01-01

    Coastal waters of the Great Barrier Reef (GBR) are contaminated with agricultural pesticides, including the photosystem II (PSII) herbicides which are the most frequently detected at the highest concentrations. Designed to control weeds, these herbicides are equally potent towards non-target marine species, and the close proximity of seagrass meadows to flood plumes has raised concerns that seagrasses may be the species most threatened by herbicides from runoff. While previous work has identified effects of PSII herbicides on the photophysiology, growth and mortality in seagrass, there is little comparative quantitative toxicity data for seagrass. Here we applied standard ecotoxicology protocols to quantify the concentrations of four priority PSII herbicides that inhibit photochemistry by 10, 20 and 50% (IC10, IC20 and IC50) over 72 h in two common seagrass species from the GBR lagoon. The photosystems of seagrasses Zosteramuelleri and Haloduleuninervis were shown to be generally more sensitive to the PSII herbicides Diuron, Atrazine, Hexazinone and Tebuthiuron than corals and tropical microalgae. The herbicides caused rapid inhibition of effective quantum yield (∆F/Fm′), indicating reduced photosynthesis and maximum effective yields (Fv/Fm) corresponding to chronic damage to PSII. The PSII herbicide concentrations which affected photosynthesis have been exceeded in the GBR lagoon and all of the herbicides inhibited photosynthesis at concentrations lower than current marine park guidelines. There is a strong likelihood that the impacts of light limitation from flood plumes and reduced photosynthesis from PSII herbicides exported in the same waters would combine to affect seagrass productivity. Given that PSII herbicides have been demonstrated to affect seagrass at environmental concentrations, we suggest that revision of environmental guidelines and further efforts to reduce PSII herbicide concentrations in floodwaters may both help protect seagrass meadows of

  11. Chromatographic methods for analysis of triazine herbicides.

    PubMed

    Abbas, Hana Hassan; Elbashir, Abdalla A; Aboul-Enein, Hassan Y

    2015-01-01

    Gas chromatography (GC) and high-performance liquid chromatography (HPLC) coupled to different detectors, and in combination with different sample extraction methods, are most widely used for analysis of triazine herbicides in different environmental samples. Nowadays, many variations and modifications of extraction and sample preparation methods such as solid-phase microextraction (SPME), hollow fiber-liquid phase microextraction (HF-LPME), stir bar sportive extraction (SBSE), headspace-solid phase microextraction (HS-SPME), dispersive liquid-liquid microextraction (DLLME), dispersive liquid-liquid microextraction based on solidification of floating organic droplet (DLLME-SFO), ultrasound-assisted emulsification microextraction (USAEME), and others have been introduced and developed to obtain sensitive and accurate methods for the analysis of these hazardous compounds. In this review, several analytical properties such as linearity, sensitivity, repeatability, and accuracy for each developed method are discussed, and excellent results were obtained for the most of developed methods combined with GC and HPLC techniques for the analysis of triazine herbicides. This review gives an overview of recent publications of the application of GC and HPLC for analysis of triazine herbicides residues in various samples. PMID:25849823

  12. Toxicity of herbicides in highway runoff.

    PubMed

    Huang, Xinjiang; Fong, Stephanie; Deanovic, Linda; Young, Thomas M

    2005-09-01

    Previous field monitoring at two highway sites found highway-applied herbicides in storm water runoff at maximum concentrations ranging from 10 microg/L for glyphosate and diuron to as high as 200 microg/L for oryzalin. To determine whether these herbicides at these concentrations can cause any toxicity to aquatic organisms, a standard toxicity study was conducted. Storm water was collected along Highway 37, Sonoma County, California, USA, and the herbicides isoxaben, oryzalin, diuron, clopyralid, and glyphosate were spiked into the storm water at the highest concentrations observed during the five previous field-monitoring campaigns. Three different toxicity studies were conducted and the results showed the following: No significant reduction in reproduction or increase in mortality relative to the control for an 8-d Ceriodaphnia (water flea) toxicity test; no significant increase in mortality or decrease in biomass compared to the control during a 7-d Pimephales (fish) toxicity test; and, in a 96-h Selenastrum (algae) toxicity test, both the 10-microg/L diuron treatment and the combined 50-microg/L isoxaben plus 200-microg/L oryzalin treatment produced significant (p < 0.05) reductions in algal growth compared to the controls, although the 30-microg/L clopyralid or 10-microg/L glyphosate treatments did not exhibit any toxic effects. PMID:16193763

  13. Synthesis and biological activity of enantiomeric pairs of phosphosulfonate herbicides.

    PubMed

    Spangler, L A; Mikolajczyk, M; Burdge, E L; Kielbasiński, P; Smith, H C; Lyzwa, P; Fisher, J D; Omelańczuk, J

    1999-01-01

    The phosphosulfonates are a new class of soil-active herbicides which control a variety of annual grass and broadleaf weeds. Chirality at the phosphorus atom afforded the opportunity to explore stereospecific requirements for herbicidal activity. Chiral (hydroxymethyl)phosphinate intermediates were enzymatically resolved (Pseudomonas fluorescens lipase) from the racemic mixtures and then used to prepare two pairs of enantiomeric phosphosulfonates. Biological testing of the enantiomeric phosphosulfonate herbicides demonstrated that, in each case, the herbicidal activity was attributed to the (+) enantiomer and that the (+) enantiomer is more active than the racemate. PMID:10563892

  14. Assessment of herbicide leaching risk in two tropical soils of Reunion Island (France).

    PubMed

    Bernard, H; Chabalier, P F; Chopart, J L; Legube, B; Vauclin, M

    2005-01-01

    Application of organic chemicals to a newly irrigated sugarcane (Saccharum officinarum L.) area located in the semiarid western part of Reunion Island has prompted local regulatory agencies to determine their potential to contaminate ground water resources. For that purpose, simple indices known as the ground water ubiquity score (Gustafson index, GUS), the retardation factor (RF), the attenuation factor (AF), and the log-transformed attenuation factor (AFT) were employed to assess the potential leaching of five herbicides in two soil types. The herbicides were alachlor [2-chloro-2',6'-diethyl-N-(methoxy-methy) acetanilide], atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-1,3,5-triazine], diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea], 2,4-D [(2,4-dichlorophenoxy) acetic-acid], and triclopyr [((3,5,6-trichloro-2-pyridyl)oxy) acetic-acid]. The soil types were Vertic (BV) and Andepts (BA) Inceptisols, which are present throughout the Saint-Gilles study area on Reunion Island. To calculate the indices, herbicide sorption (K(oc)) and dissipation (half-life, DT50) properties were determined from controlled batch experiments. Water fluxes below the root zone were estimated by a capacity-based model driven by a rainfall frequency analysis performed on a 13-yr data series. The results show a lower risk of herbicide leaching than in temperate regions due to the tropical conditions of the study area. Higher temperatures and the presence of highly adsorbent soils may explain smaller DT50 and higher K(oc) values than those reported in literature concerning temperate environments. Based on the RF values, only 2,4-D and triclopyr appear mobile in the BV soil, with all the other herbicides being classified from moderately to very immobile in both soils. The AFT values indicate that the potential leaching of the five herbicides can be considered as unlikely, except during the cyclonic period (about 40 d/yr) when there is a 2.5% probability of recharge rates equal to or

  15. Carrier-mediated extraction of bipyridilium herbicides across the hydrophobic liquid membrane.

    PubMed

    Mulugeta, Mesay; Megersa, Negussie

    2004-09-01

    Supported liquid membrane (SLM) method for preconcentration and enrichment of the two bipyridilium herbicides, namely diquat and paraquat, from environmental water samples has been developed. The permanently charged cationic herbicides were extracted from a flowing aqueous solution to a stagnant acidic acceptor solution across a liquid membrane containing 40% (v/v) di-(2-ethylhexyl) phosphoric acid dissolved in di-n-hexyl ether. The mass transfer of analytes is driven by the counter-coupled transport of hydrogen ions from the acceptor to the donor phase. The efficiency of the extraction process depends on the donor solution pH, the amount of the mobile carrier added to the liquid membrane and the concentration of the counter ion in the acceptor solution. The applicability of the method for extraction of these quaternary ammonium herbicides from environmental waters was also investigated by spiking analyte sample solutions in river water. With 24h sample enrichment concentrations of diquat and paraquat down to ca. 10ng/L could be detected in environmental waters. PMID:18969573

  16. Broad 4-hydroxyphenylpyruvate dioxygenase inhibitor herbicide tolerance in soybean with an optimized enzyme and expression cassette.

    PubMed

    Siehl, Daniel L; Tao, Yumin; Albert, Henrik; Dong, Yuxia; Heckert, Matthew; Madrigal, Alfredo; Lincoln-Cabatu, Brishette; Lu, Jian; Fenwick, Tamara; Bermudez, Ericka; Sandoval, Marian; Horn, Caroline; Green, Jerry M; Hale, Theresa; Pagano, Peggy; Clark, Jenna; Udranszky, Ingrid A; Rizzo, Nancy; Bourett, Timothy; Howard, Richard J; Johnson, David H; Vogt, Mark; Akinsola, Goke; Castle, Linda A

    2014-11-01

    With an optimized expression cassette consisting of the soybean (Glycine max) native promoter modified for enhanced expression driving a chimeric gene coding for the soybean native amino-terminal 86 amino acids fused to an insensitive shuffled variant of maize (Zea mays) 4-hydroxyphenylpyruvate dioxygenase (HPPD), we achieved field tolerance in transgenic soybean plants to the HPPD-inhibiting herbicides mesotrione, isoxaflutole, and tembotrione. Directed evolution of maize HPPD was accomplished by progressively incorporating amino acids from naturally occurring diversity and novel substitutions identified by saturation mutagenesis, combined at random through shuffling. Localization of heterologously expressed HPPD mimicked that of the native enzyme, which was shown to be dually targeted to chloroplasts and the cytosol. Analysis of the native soybean HPPD gene revealed two transcription start sites, leading to transcripts encoding two HPPD polypeptides. The N-terminal region of the longer encoded peptide directs proteins to the chloroplast, while the short form remains in the cytosol. In contrast, maize HPPD was found almost exclusively in chloroplasts. Evolved HPPD enzymes showed insensitivity to five inhibitor herbicides. In 2013 field trials, transgenic soybean events made with optimized promoter and HPPD variant expression cassettes were tested with three herbicides and showed tolerance to four times the labeled rates of mesotrione and isoxaflutole and two times the labeled rates of tembotrione. PMID:25192697

  17. Preparative-scale synthesis of two metabolites isolated from soil treated with zoxium fungicide and kerb herbicide.

    PubMed

    Michelotti, Enrique L; Borrell, José I; Roemmele, Renee; Matallana, Josep L; Teixidó, Jordi; Bryman, Lois M

    2002-01-30

    The preparation in multigram scale of two metabolites 3-(3,5-dichloro-4-methyl-benzoylamino)-2-hydroxy-3-methyl-pentanoic acid and 3-(3,5-dichloro-benzoylamino)-3-methyl-2-oxo-butyric acid isolated from soil treated with either Zoxium fungicide or Kerb herbicide was efficiently accomplished using a common 5-step synthetic process starting from easily available raw materials. PMID:11804519

  18. DNA Analysis of Herbarium Specimens of the Grass Weed Alopecurus myosuroides Reveals Herbicide Resistance Pre-Dated Herbicides

    PubMed Central

    Délye, Christophe; Deulvot, Chrystel; Chauvel, Bruno

    2013-01-01

    Acetyl-CoA carboxylase (ACCase) alleles carrying one point mutation that confers resistance to herbicides have been identified in arable grass weed populations where resistance has evolved under the selective pressure of herbicides. In an effort to determine whether herbicide resistance evolves from newly arisen mutations or from standing genetic variation in weed populations, we used herbarium specimens of the grass weed Alopecurus myosuroides to seek mutant ACCase alleles carrying an isoleucine-to-leucine substitution at codon 1781 that endows herbicide resistance. These specimens had been collected between 1788 and 1975, i.e., prior to the commercial release of herbicides inhibiting ACCase. Among the 734 specimens investigated, 685 yielded DNA suitable for PCR. Genotyping the ACCase locus using the derived Cleaved Amplified Polymorphic Sequence (dCAPS) technique identified one heterozygous mutant specimen that had been collected in 1888. Occurrence of a mutant codon encoding a leucine residue at codon 1781 at the heterozygous state was confirmed in this specimen by sequencing, clearly demonstrating that resistance to herbicides can pre-date herbicides in weeds. We conclude that point mutations endowing resistance to herbicides without having associated deleterious pleiotropic effects can be present in weed populations as part of their standing genetic variation, in frequencies higher than the mutation frequency, thereby facilitating their subsequent selection by herbicide applications. PMID:24146749

  19. Underlying Resistance Mechanisms in the Cynosurus echinatus Biotype to Acetyl CoA Carboxylase-Inhibiting Herbicides.

    PubMed

    Fernández, Pablo; Alcántara-de la Cruz, Ricardo; Cruz-Hipólito, Hugo; Osuna, María D; De Prado, Rafael

    2016-01-01

    Hedgehog dogtail (Cynosurus echinatus) is an annual grass, native to Europe, but also widely distributed in North and South America, South Africa, and Australia. Two hedgehog dogtail biotypes, one diclofop-methyl (DM)-resistant and one DM-susceptible were studied in detail for experimental dose-response resistance mechanisms. Herbicide rates that inhibited shoot growth by 50% (GR50) were determined for DM, being the resistance factor (GR50R/GR50S) of 43.81. When amitrole (Cyt. P450 inhibitor) was applied before treatment with DM, the R biotype growth was significantly inhibited (GR50 of 1019.9 g ai ha(-1)) compared with the GR50 (1484.6 g ai ha(-1)) found for the R biotype without pretreatment with amitrole. However, GR50 values for S biotype do not vary with or without amitrole pretreatment. Dose-response experiments carried out to evaluate cross-resistance, showed resistance to aryloxyphenoxypropionate (APP), cyclohexanedione (CHD) and phenylpyrazoline (PPZ) inhibiting herbicides. Both R and S biotypes had a similar (14)C-DM uptake and translocation. The herbicide was poorly distributed among leaves, the rest of the shoot and roots with unappreciable acropetal and/or basipetal DM translocation at 96 h after treatment (HAT). The metabolism of (14)C-DM, D-acid and D-conjugate metabolites were identified by thin-layer chromatography. The results showed that DM resistance in C. echinatus is likely due to enhanced herbicide metabolism, involving Cyt. P450 as was demonstrated by indirect assays (amitrole pretreatment). The ACCase in vitro assays showed that the target site was very sensitive to APP, CHD and PPZ herbicides in the C. echinatus S biotype, while the R biotype was insensitive to the previously mentioned herbicides. DNA sequencing studies confirmed that C. echinatus cross-resistance to ACCase inhibitors has been conferred by specific ACCase double point mutations Ile-2041-Asn and Cys-2088-Arg. PMID:27148285

  20. Underlying Resistance Mechanisms in the Cynosurus echinatus Biotype to Acetyl CoA Carboxylase-Inhibiting Herbicides

    PubMed Central

    Fernández, Pablo; Alcántara-de la Cruz, Ricardo; Cruz-Hipólito, Hugo; Osuna, María D.; De Prado, Rafael

    2016-01-01

    Hedgehog dogtail (Cynosurus echinatus) is an annual grass, native to Europe, but also widely distributed in North and South America, South Africa, and Australia. Two hedgehog dogtail biotypes, one diclofop-methyl (DM)-resistant and one DM-susceptible were studied in detail for experimental dose-response resistance mechanisms. Herbicide rates that inhibited shoot growth by 50% (GR50) were determined for DM, being the resistance factor (GR50R/GR50S) of 43.81. When amitrole (Cyt. P450 inhibitor) was applied before treatment with DM, the R biotype growth was significantly inhibited (GR50 of 1019.9 g ai ha-1) compared with the GR50 (1484.6 g ai ha-1) found for the R biotype without pretreatment with amitrole. However, GR50 values for S biotype do not vary with or without amitrole pretreatment. Dose-response experiments carried out to evaluate cross-resistance, showed resistance to aryloxyphenoxypropionate (APP), cyclohexanedione (CHD) and phenylpyrazoline (PPZ) inhibiting herbicides. Both R and S biotypes had a similar 14C-DM uptake and translocation. The herbicide was poorly distributed among leaves, the rest of the shoot and roots with unappreciable acropetal and/or basipetal DM translocation at 96 h after treatment (HAT). The metabolism of 14C-DM, D-acid and D-conjugate metabolites were identified by thin-layer chromatography. The results showed that DM resistance in C. echinatus is likely due to enhanced herbicide metabolism, involving Cyt. P450 as was demonstrated by indirect assays (amitrole pretreatment). The ACCase in vitro assays showed that the target site was very sensitive to APP, CHD and PPZ herbicides in the C. echinatus S biotype, while the R biotype was insensitive to the previously mentioned herbicides. DNA sequencing studies confirmed that C. echinatus cross-resistance to ACCase inhibitors has been conferred by specific ACCase double point mutations Ile-2041-Asn and Cys-2088-Arg. PMID:27148285

  1. Herbicides and herbicide degradation products in upper midwest agricultural streams during august base-flow conditions

    USGS Publications Warehouse

    Kalkhoff, S.J.; Lee, K.E.; Porter, S.D.; Terrio, P.J.; Thurman, E.M.

    2003-01-01

    Herbicide concentrations in streams of the U.S. Midwest have been shown to decrease through the growing season due to a variety of chemical and physical factors. The occurrence of herbicide degradation products at the end of the growing season is not well known. This study was conducted to document the occurrence of commonly used herbicides and their degradation products in Illinois, Iowa, and Minnesota streams during base-flow conditions in August 1997. Atrazine, the most frequently detected herbicide (94%), was present at relatively low concentrations (median 0.17 μg L−1). Metolachlor was detected in 59% and cyanazine in 37% of the samples. Seven of nine compounds detected in more than 50% of the samples were degradation products. The total concentration of the degradation products (median of 4.4 μg L−1) was significantly greater than the total concentration of parent compounds (median of 0.26 μg L−1). Atrazine compounds were present less frequently and in significantly smaller concentrations in streams draining watersheds with soils developed on less permeable tills than in watersheds with soils developed on more permeable loess. The detection and concentration of triazine compounds was negatively correlated with antecedent rainfall (April–July). In contrast, acetanalide compounds were positively correlated with antecedant rainfall in late spring and early summer that may transport the acetanalide degradates into ground water and subsequently into nearby streams. The distribution of atrazine degradation products suggests regional differences in atrazine degradation processes.

  2. Sarmentine, a natural herbicide from Piper species with multiple herbicide mechanisms of action

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sarmentine, 1-(1-pyrrolidinyl)-(2E,4E)-2,4-decadien-1-one, is a natural amide isolated from the fruits of Piper species. The compound has a number of interesting biological properties, including its broad-spectrum activity on weeds as a contact herbicide. Initial studies highlighted a similarity in ...

  3. Racer as a potential organic herbicide: Application volumes and herbicide rates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Racer (40% ammonium pelargonate/ammonium nonanoate) is labeled for non-food use and efforts are currently underway to label it as a bio-herbicide for organically grown food crops. The main component of Racer is ammonium pelargonate which occurs in nature and is primarily formed from biodegradation ...

  4. Herbicide volatilization trumps runoff losses, a multi-year investigation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Surface runoff and volatilization are two processes critical to herbicide off-site transport. To determine the relevance of these off-site transport mechanisms, runoff and turbulent vapor fluxes were simultaneously monitored on the same site for eight years. Site location, herbicide formulations, ...

  5. Confirmation of resistance to herbicides and evaluation of resistance levels

    Technology Transfer Automated Retrieval System (TEKTRAN)

    As cases of resistance to herbicides escalate worldwide, there is increasing demand from growers to test for weed resistance and how to manage it. Scientists have developed resistance testing protocols for numerous herbicides and weed species. Growers need immediate answers and scientists are faced ...

  6. Are Herbicide Resistant Crops The Answer To Controlling Cascuta?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Herbicide tolerant crop technology could provide new management strategies for the control of parasitic plants. Three herbicide-tolerant oilseed rape genotypes were used to examine the response of attached C. campestris to glyphosate, imazamox and glufosinate. C. campestris was allowed to establi...

  7. TOXICITY, BIOCONCENTRATION, AND METABOLISM OF FIVE HERBICIDES IN FRESHWATER FISH

    EPA Science Inventory

    Acute and early life-stage toxicities were determined for the herbicides alachlor, bromacil, dinoseb, diuron, and propanil with the fathead minnow (Pimephales promelas). Uptake, bioconcentration potential, and elimination of 14C-labeled herbicides were studied in the same species...

  8. Weed resistance challenges and management under herbicide resistant cropping systems

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Over the last six decades, herbicides have been the mainstay of weed management in cropping systems around the world, especially in the Western Hemisphere. A direct consequence of intensive use of herbicides is the development of resistance in weed populations. The extreme popularity of transgenic g...

  9. Growth Regulator Herbicides Prevent Invasive Annual Grass Seed Production

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Auxinic herbicides, such as 2,4-D and dicamba, that act as plant growth regulators are commonly used for broadleaf weed control in cereal crops (e.g. wheat, barley), grasslands, and non-croplands. If applied at later growth stages, while cereals are developing reproductive parts, the herbicides can...

  10. ACETANILIDE HERBICIDE DEGRADATION PRODUCTS BY LC/MS

    EPA Science Inventory

    Acetanilide herbicides are frequently applied in the U.S. on crops (corn, soybeans, popcorn, etc.) to control broadleaf and annual weeds. The acetanilide and acetamide herbicides currently registered for use in the U.S. are alachlor, acetochlor, metolachlor, propachlor, flufen...

  11. Thirteen year summary of field-scale herbicide volatilization

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Once lost to the atmosphere, herbicide transport can result in unintended re-deposition to inhabited areas, streams, rivers, and lakes. To better understand factors governing herbicide volatilization and to determine its impact relative to other loss pathways, field-scale turbulent volatilization fl...

  12. Herbicide resistant crops: history, development, and current technologies

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Advances in biotechnology have led to development and commercialization of several herbicide-resistant crops (HRCs) in the mid-1990s. HRCs survive herbicide treatment that previously would have killed the crop along with targeted weeds. Both transgenic (created through stable integration of a foreig...

  13. Factors Influencing Observed Tillage Impacts on Herbicide Transport

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The widespread use and potential human health effects of the herbicides atrazine and glyphosate have generated interest in establishing how no-tillage impacts loading of these herbicides to runoff water in comparison to other tillage practices. In this study, potentially confounding factors such as ...

  14. Herbicide-resistant crop biotechnology: potential and pitfalls

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Herbicide-resistant crops are an important agricultural biotechnology that can enable farmers to effectively control weeds without harming their crops. Glyphosate-resistant (i.e. Roundup Ready) crops have been the most commercially successful varieties of herbicide-resistant crops and have been plan...

  15. Spatial variation in sorption and dissipation is herbicide-dependent

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In eroded landforms, soil properties that influence herbicide fate are highly variable with landscape position. Understanding the variation in herbicide sorption and dissipation is essential to characterize weed control efficacy and availability for off-site transport. We evaluated the sorption and/...

  16. Kudzu Suppression by Herbicides in Two-Year Field trials

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Herbicides are currently the principle means of halting the spread of kudzu (Pueraria montana var lobata) and reclaiming kudzu-infested lands. The efficacy of several herbicides on this invasive weed has been well-established, but these chemicals can be prohibitively expensive, come with significan...

  17. Crop competitive ability contributes to herbicide performance in sweet corn

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Crop variety effect on herbicide performance is not well characterized, particularly for sweet corn, a crop that varies greatly among hybrids in competitive ability with weeds. Field studies were used to determine the effect of crop competitive ability on season-long herbicide performance in sweet c...

  18. Post-directed application of potential organic herbicides for onions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Organic onion producers need appropriate herbicides that can effectively provide post-emergent weed control. Research was conducted in southeast Oklahoma (Atoka County, Lane, OK) to determine the impact of potential organic herbicides on weed control efficacy, crop injury, and yields. The experime...

  19. Herbicide Leaching Column for a Weed Science Teaching Laboratory.

    ERIC Educational Resources Information Center

    Ahrens, W. H.

    1986-01-01

    Presents an experiment which enables weed science students to observe first-hand the process of herbicide leaching in soils. Features of this technique which demonstrate the movement of herbicide within a column of soil are outlined. Diagrams are provided of the apparatus employed in the exercise. (ML)

  20. Cross and Multiple Herbicide Resistance in Palmer amaranth (Amaranthus palmeri)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Resistance of Palmer amaranth (PA) to ALS inhibitor herbicides was discovered in Georgia in 2000 and resistance to glyphosate was in 2005. A study was conducted to evaluate two different families of ALS herbicides, imazapic (imidazolinone) and diclosulam (sulfonanilides) for absorption and mobility ...

  1. Rationale for a natural products approach to herbicide discovery

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Weeds continue to evolve resistance to all the known modes of herbicidal action, but no herbicide with a new target site has been commercialized in nearly 20 years. The so-called ‘new chemistries’ are simply molecules belonging to new chemical classes that have the same mechanisms of action as olde...

  2. Manuka oil a natural herbicide with preemergence activity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Natural herbicides approved in organic agriculture are primarily non-selective burn-down essential oils applied POST. Multiple applications are often required due to their low efficacy. To address this problem, the in vivo herbicidal activity of manuka oil, the essential oil distilled from Leptosp...

  3. POTENTIAL ENVIRONMENTAL RISKS ASSOCIATED WITH THE NEW SULFONYLUREA HERBICIDES

    EPA Science Inventory

    The first sulfonylurea herbicide, chlorsulfuron was introduced in 1982. embers of this new herbicide class are known for their high toxicity toward plant growth, low application rate, extremely low toxicity to humans and other animals, and phytotoxicity reported due to the inhibi...

  4. Herbicide Incorporation by Irrigation and Tillage Impact on Runoff Loss

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Runoff from farm fields is a common source of herbicide residues detected in surface waters. Soil incorporation by post-herbicide application irrigation has the potential to reduce runoff risks and improve weed control efficacy. To assess runoff impacts, we conducted rainfall simulations following p...

  5. Circadian response of annual weeds in a natural setting to high and low application rates of four herbicides with different modes of actions.

    PubMed

    Miller, Ryan P; Martinson, Krishona B; Sothern, Robert B; Durgan, Beverly R; Gunsolus, Jeffrey L

    2003-03-01

    Four herbicides [glyphosate (GLYT), an amino acid synthesis inhibitor; glufosinate (GLUF), a glutamine synthetase inhibitor; fomesafen (FOME), a protoporphyrinogen oxidase inhibitor, and chlorimuron ethyl (CLIM), an acetolactate synthase inhibitor] were used to examine the influence of time of day of application on the control of a variety of annual broadleaf weeds in field studies conducted in Minnesota (five studies on GLYT and GLUF, three studies on FOME and CLIM). All herbicides were applied with an adjuvant at recommended high and low (half or quarter strength) rates every 3h between 06:00 and 24:00h local time. Visual ratings of percent weed control evaluated at 14d were analyzed by herbicide and application rate for each study and across studies for time-of-day effect by analysis of variance (ANOVA) and single cosinor. A circadian response to each herbicide was found, with greatest weed control observed between 09:00 and 18:00h. Increasing the herbicide application rate did not overcome the time-of-day effect (ANOVA: p < or = 0.008 for time-of-day effect for each herbicide and application rate). The least-squares fit of a 24h cosine was significant (p < or = 0.001) for each herbicide and application rate, with double amplitudes of 18-82% (units = % visual control) and estimated peaks (acrophases) near midday between 12:40 and 13:35h. Analysis of residuals obtained from multiple regression that included weed height, herbicide rate, temperature, and relative humidity as independent factors also found a significant time-effect by both ANOVA and cosinor for each herbicide and rate, with acrophases advancing significantly by 3 to 7h for GLYT and GLUF, but not for FOME or CLIM. These results suggest that the four herbicides, while belonging to different families with different modes of action, may reveal different peak times of efficacy when adjusting for environmental factors. Nonetheless, each displays similar circadian patterns when influenced by these factors

  6. Residual and contact herbicide transport through field lysimeters via preferential flow.

    PubMed

    Malone, R W; Shipitalo, M J; Wauchope, R D; Sumner, H

    2004-01-01

    Usage of glyphosate [N-(phosphonomethyl)-glycine] and glufosinate [2-amino-4-(hydroxy-methylphosphinyl)butanoic acid] may reduce the environmental impact of agriculture because they are more strongly sorbed to soil and may be less toxic than many of the residual herbicides they replace. Preferential flow complicates the picture, because due to this process, even strongly sorbed chemicals can move quickly to ground water. Therefore, four monolith lysimeters (8.1 m(2) by 2.4 m deep) were used to investigate leaching of contact and residual herbicides under a worst-case scenario. Glufosinate, atrazine (6-chloro-N(2)-ethyl-N(4)-isopropyl-1,3,5-triazine-2,4-diamine), alachlor [2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl) acetamide], and linuron (3-3,4-dichlorophenyl-1-methoxy-1-methylurea) were applied in 1999 before corn (Zea mays L.) planting and glyphosate, alachlor, and metribuzin [4-amino-6-(1,1-dimethylethyl)-3-(methylthio)-1,2,4-triazin-5(4H)-one] were applied in 2000 before soybean [Glycine max (L.) Merr.] planting. A high-intensity rainfall was applied shortly after herbicide application both years. Most alachlor, metribuzin, atrazine, and linuron losses occurred within 1.1 d of rainfall initiation and the peak concentration of the herbicides coincided (within 0.1 d of rainfall initiation in 2000). More of the applied metribuzin leached compared with alachlor during the first 1.1 d after rainfall initiation (2.2% vs. 0.035%, P < 0.05). In 1999, 10 of 24 discrete samples contained atrazine above the maximum contaminant level (atrazine maximum contaminant level [MCL] = 3 mug L(-1)) while only one discrete sample contained glufosinate (19 mug L(-1), estimated MCL = 150 mug L(-1)). The results indicate that because of preferential flow, the breakthrough time of herbicides was independent of their sorptive properties but the transport amount was dependent on the herbicide properties. Even with preferential flow, glyphosate and glufosinate were not transported to

  7. Groundwater resources impact assessment for triazine herbicides

    SciTech Connect

    Waldman, E.; Barrett, M.R.; Behl, E.

    1996-10-01

    The Environmental Fate and Ground Water Branch of EPA`s Office of Pesticide Programs (OPP) has conducted a Water Resources Impact Assessment of the potential for triazine herbicides to be transported to ground and surface waters (only ground-water is discussed in this paper). The herbicides discussed in this document include atrazine, cyanazine, simazine, and prometon. Part of OPP`s regulatory mission is to prevent contamination of ground and surface water resources resulting from the normal use of registered pesticides. OPP has recently produced several resource documents to support such activities at the federal, state, and local levels (e.g., the Pesticides and Ground-Water Strategy and the Pesticides in Ground Water Database). This Water Resources Impact Assessment will also be useful in assisting state and regional agencies in customizing risk reduction strategies and to implement proposed pollution prevention measures. Major conclusions include: Atrazine is the most frequently detected pesticide in ground water in virtually the entire Midwestern United States, and especially in Nebraska, Iowa, Illinois, and Indiana. The Pesticides in Ground Water Database 1992 Report indicates that atrazine has been detected in 32 out of the 40 states that have reported monitoring data, and in 1,512 wells (6%) of the wells sampled. Based on EPA`s National Pesticide Survey (NPS), 4.7% of rural domestic drinking water wells in the U.S. (490,000 wells) are estimated to contain atrazine, mostly at concentrations less than 0.12 {mu}g/L (the MCL for atrazine is 3 {mu}g/L). Triazine herbicides other than atrazine (simazine, cyanazine, and prometon) have had much less impact on ground-water quality than atrazine, primarily because they are less intensively used.

  8. Adsorption of herbicides using activated carbons

    SciTech Connect

    Derbyshire, F.; Jagtoyan, M.; Lafferty, C.; Kimber, G.

    1996-10-01

    This work describes development of a series of novel activated carbon materials and their testing for possible water treatment applications by studying the adsorption of sodium pentachlorphenolate, PCP (a common herbicide/wood preservative). Although the application of activated carbons is an established technology for the treatment of public water supplies, there is a growing need for materials with higher selectivity and adsorptive capacities as well as high abrasion resistance. The materials that will be discussed include extruded wood-derived carbons with novel pore size distributions and high hardness, as well as activated carbon fiber composites. Comparisons will be made with commercial granular water treatment carbons.

  9. Effects of herbicide applications in wheat fields

    PubMed Central

    Varshney, Sugandha; Hayat, Shamshul; Alyemeni, Mohammed Nasser; Ahmad, Aqil

    2012-01-01

    The present review encompasses the physiological and yield constraints of herbicide applications with special reference to wheat productivity. Post-independence lagging of Indian agriculture to feed its population led to haphazard use of chemical pesticides and weedicides which deteriorated the productivity pay-off particularly of wheat and rice. Past some decades witnessed the potential use of certain phytohormones in augmenting abiotic stress to get rid of yield gap and productivity constraints. We summed up with reviewing the potential role of these natural regulators in overcoming above mentioned drawbacks to substitute or to integrate these chemicals with the use of plant hormones. PMID:22516826

  10. Fate of Herbicides and Their Degradation Products Entering a Forested Riparian Buffer Following Herbicides Application to an Adjacent Corn Field

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The fate of two herbicides, atrazine and metolachlor, were followed as they entered and moved through a forested riparian wetland located in the mid-Atlantic coastal plain of Maryland. The herbicides were applied as pre-emergent treatments to a 20-ha corn field directly upgradient of the riparian w...

  11. Proteomic and histopathological response in the gills of Poecilia reticulata exposed to glyphosate-based herbicide.

    PubMed

    Rocha, Thiago Lopes; Santos, Ana Paula Rezende Dos; Yamada, Áureo Tatsumi; Soares, Célia Maria de Almeida; Borges, Clayton Luiz; Bailão, Alexandre Melo; Sabóia-Morais, Simone Maria Teixeira

    2015-07-01

    Glyphosate-based herbicides (GBH) are one of the most used herbicide nowadays, whilst there is growing concern over their impact on aquatic environment. Since data about the early proteomic response and toxic mechanisms of GBH in fish is very limited, the aim of this study was to investigate the early toxicity of GBH in the gills of guppies Poecilia reticulata using a proteomic approach associated with histopathological index. Median lethal concentration (LC50,96 h) was determined and LC50,96h values of guppies exposed to GBH were 3.6 ± 0.4 mg GLIL(-1). Using two-dimensional gel electrophoresis associated with mass spectrometry, 14 proteins regulated by GBH were identified, which are involved in different cell processes, as energy metabolism, regulation and maintenance of cytoskeleton, nucleic acid metabolism and stress response. Guppies exposed to GBH at 1.82 mg GLIL(-1) showed time-dependent histopathological response in different epithelial and muscle cell types. The histopathological indexes indicate that GBH cause regressive, vascular and progressive disorders in the gills of guppies. This study helped to unravel the molecular and tissue mechanisms associated with GBH toxicity, which are potential biomarkers for biomonitoring water pollution by herbicides. PMID:26141659

  12. 2,4-D resistance in wild radish: reduced herbicide translocation via inhibition of cellular transport

    PubMed Central

    Goggin, Danica E.; Cawthray, Gregory R.; Powles, Stephen B.

    2016-01-01

    Resistance to auxinic herbicides is increasing in a range of dicotyledonous weed species, but in most cases the biochemical mechanism of resistance is unknown. Using 14C-labelled herbicide, the mechanism of resistance to 2,4-dichlorophenoxyacetic acid (2,4-D) in two wild radish (Raphanus raphanistrum L.) populations was identified as an inability to translocate 2,4-D out of the treated leaf. Although 2,4-D was metabolized in wild radish, and in a different manner to the well-characterized crop species wheat and bean, there was no difference in metabolism between the susceptible and resistant populations. Reduced translocation of 2,4-D in the latter was also not due to sequestration of the herbicide, or to reduced uptake by the leaf epidermis or mesophyll cells. Application of auxin efflux or ABCB transporter inhibitors to 2,4-D-susceptible plants caused a mimicking of the reduced-translocation resistance phenotype, suggesting that 2,4-D resistance in the populations under investigation could be due to an alteration in the activity of a plasma membrane ABCB-type auxin transporter responsible for facilitating long-distance transport of 2,4-D. PMID:26994475

  13. Remediation of waters contaminated with ionic herbicides by sorption on polymerin.

    PubMed

    Sannino, F; Iorio, M; De Martino, A; Pucci, M; Brown, C D; Capasso, R

    2008-02-01

    This study investigated the sorption of paraquat and 2,4-D on polymerin, the humic acid-like fraction of olive mill wastewater. Effects of pH, contact time, initial concentration and sorbent dosage on the sorption of both herbicides were studied. The sorption mechanism of paraquat on polymerin was consistent with the ion exchange of this herbicide with Ca, Mg and K natively occurring in the sorbent; in contrast, 2,4-D was bound to polymerin by hydrogen bonding. Simulated wastewaters contaminated with paraquat were purified after three sorption cycles on polymerin renewed at each cycle, at a solid/liquid ratio of 0.5, whereas those containing 2,4-D showed a maximal residue removal of 44% after two sorption cycles at the same ratio. The possible application of this model to other water-soluble herbicides, as well as the possible exploitation of polymerin as a bio-filter for the decontamination of pollution point sources is briefly discussed. PMID:17904611

  14. 2,4-D resistance in wild radish: reduced herbicide translocation via inhibition of cellular transport.

    PubMed

    Goggin, Danica E; Cawthray, Gregory R; Powles, Stephen B

    2016-05-01

    Resistance to auxinic herbicides is increasing in a range of dicotyledonous weed species, but in most cases the biochemical mechanism of resistance is unknown. Using (14)C-labelled herbicide, the mechanism of resistance to 2,4-dichlorophenoxyacetic acid (2,4-D) in two wild radish (Raphanus raphanistrum L.) populations was identified as an inability to translocate 2,4-D out of the treated leaf. Although 2,4-D was metabolized in wild radish, and in a different manner to the well-characterized crop species wheat and bean, there was no difference in metabolism between the susceptible and resistant populations. Reduced translocation of 2,4-D in the latter was also not due to sequestration of the herbicide, or to reduced uptake by the leaf epidermis or mesophyll cells. Application of auxin efflux or ABCB transporter inhibitors to 2,4-D-susceptible plants caused a mimicking of the reduced-translocation resistance phenotype, suggesting that 2,4-D resistance in the populations under investigation could be due to an alteration in the activity of a plasma membrane ABCB-type auxin transporter responsible for facilitating long-distance transport of 2,4-D. PMID:26994475

  15. Mode of Action Studies on a Chiral Diphenyl Ether Peroxidizing Herbicide

    PubMed Central

    Hallahan, Beverly J.; Camilleri, Patrick; Smith, Alison; Bowyer, John R.

    1992-01-01

    The nitrodiphenyl ether herbicide 5-[2-chloro-4-(trifluoromethyl)phenoxy]-2-nitroacetophenone oxime-O-(acetic acid, methyl ester) (DPEI) induced an abnormal accumulation of protoporphyrin IX in darkness in the green alga Chlamydomonas reinhardtii, as determined by high-performance liquid chromatography and spectrofluorimetry. It also inhibited the increase in cell density of the alga in light-grown cultures with an I50 (concentration required to decrease cell density increase to 50% of the noninhibited control value) of 0.16 μm. The relative ability of four peroxidizing diphenyl ether herbicides to cause tetrapyrrole accumulation in C. reinhardtii correlated qualitatively with their ability to inhibit the increase in cell density in light-grown cultures. The purified S(−) enantiomer of the optically active phthalide DPE 5-[2-chloro-4-(trifluoromethyl)phenoxy]-3-methylphthalide (DPEIII), which has greater herbicidal activity than the R(+) isomer, induces a 4- to 5-fold greater tetrapyrrole accumulation than the R(+) isomer. The I50 for inhibition of increase in cell density in light-grown cultures of C. reinhardtii by the S(−) isomer (0.019 μm) is less than 25% of that for the R(+) isomer. DPEIII inhibits protoporphyrinogen IX oxidase activity in pea (Pisum sativum) etioplast lysates, with the S(−) enantiomer showing considerably greater potency than the R(+) isomer and the racemic mixture showing a potency intermediate between the two. The results indicate that the site at which DPEs inhibit protoporphyrinogen IX oxidase shows chiral discrimination and provide further evidence for the link between inhibition of this enzyme, protoporphyrin IX accumulation, and the phytotoxicity of DPE herbicides. PMID:16653107

  16. Research methods in weed science: herbicide absorption and translocation in plants using radioisotopes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Herbicide absorption and translocation in plants is a key component in the study of herbicide physiology, mode of action, selectivity, resistance mechanisms, and in the registration process. Radioactive herbicides have been in use for over half-a-century in the research and study of herbicide absorp...

  17. Real World of Industrial Chemistry: The Challenge of Herbicides for Aquatic Weeds.

    ERIC Educational Resources Information Center

    Martin, Dean F.; Martin, Barbara B.

    1985-01-01

    Discusses problems in selecting the correct herbicide for use in controlling aquatic weeds, considering specificity, size of the market, fear of trace contaminants, and herbicide resistance in weeds. Also summarizes some successful herbicides, providing a table listing mode of action of some herbicides used for control of aquatic plants. (JN)

  18. Spatial variation in sorption-desorption of the herbicide saflufenacil in an eroded prairie landscape

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Herbicide interactions with soil determine their availability for plant uptake, transport, and degradation. The kinetics and extent of herbicide partitioning and transformation in soil are affected by properties of the herbicide and of the soil. The herbicide saflufenacil was registered in the US in...

  19. Washoff of Residual Photosystem II Herbicides from Sugar Cane Trash under a Rainfall Simulator.

    PubMed

    Dang, Aaditi; Silburn, Mark; Craig, Ian; Shaw, Melanie; Foley, Jenny

    2016-05-25

    Herbicides are often applied to crop residues, but their fate has not been well studied. We measured herbicide washoff from sugar cane trash during simulated rainfall, at 1, 8, and 40 days after spraying (DAS), to provide insight into herbicide fate and for use in modeling. Herbicides included are commonly used in the sugar industry, either in Australia or in Brazil. Concentrations of all herbicides and applied Br tracer in washoff declined exponentially over time. The rate of washoff during rainfall declined with increasing DAS. Cumulative washoff as a function of rainfall was similar for most herbicides, although the most soluble herbicides did have more rapid washoff. Some but not all herbicides became more resistant to washoff with increasing DAS. Of the total mass washed off, 80% washed off in the first 30 mm (∼40 min) of rainfall for most herbicides. Little herbicide remained on the trash after rainfall, implying nearly complete washoff. PMID:26964670

  20. Protocols for Robust Herbicide Resistance Testing in Different Weed Species.

    PubMed

    Panozzo, Silvia; Scarabel, Laura; Collavo, Alberto; Sattin, Maurizio

    2015-01-01

    Robust protocols to test putative herbicide resistant weed populations at whole plant level are essential to confirm the resistance status. The presented protocols, based on whole-plant bioassays performed in a greenhouse, can be readily adapted to a wide range of weed species and herbicides through appropriate variants. Seed samples from plants that survived a field herbicide treatment are collected and stored dry at low temperature until used. Germination methods differ according to weed species and seed dormancy type. Seedlings at similar growth stage are transplanted and maintained in the greenhouse under appropriate conditions until plants have reached the right growth stage for herbicide treatment. Accuracy is required to prepare the herbicide solution to avoid unverifiable mistakes. Other critical steps such as the application volume and spray speed are also evaluated. The advantages of this protocol, compared to others based on whole plant bioassays using one herbicide dose, are related to the higher reliability and the possibility of inferring the resistance level. Quicker and less expensive in vivo or in vitro diagnostic screening tests have been proposed (Petri dish bioassays, spectrophotometric tests), but they provide only qualitative information and their widespread use is hindered by the laborious set-up that some species may require. For routine resistance testing, the proposed whole plant bioassay can be applied at only one herbicide dose, so reducing the costs. PMID:26167668

  1. Herbicidal treatments for control of Cannabis sativa L.

    PubMed

    Horowitz, M

    1977-01-01

    In order to test herbicides for the destruction of illicit stands of cannabis (Cannabis sativa L.) a series of commercially available herbicides were sprayed on glasshouse-grown plants having 2 to 6 leaves. The following herbicides caused complete kill or severe injury to cannabis plants: (a) herbicides with root and foliage activity--ametryn, atrazine, metribuzin, prometryn, terbutryne, diuron, fluometuron, linuron, methabenzthiazuron, phenobenzuron, ethofumesate, karbutilate, methazole and oxadiazon; and (b) foliar-acting herbicides with brief or no soil persistence--amitrole, bentazon, 2,4-D, diquat + paraquat, glyphosate and phenmedipham. In field experiments herbicides of the latter group, and ioxynil, metribuzin, and a MSMA-cacodylate mixture, caused death or severe damage to young cannabis plants. Glyphosate, ioxynil and bentazon destroyed developed cannabis plants. In glasshouse and field experiments the following herbicides applied to young cannabis plants caused marked deformations of stems, leaves and/or inflorescences: barban, butralin, dalapon, difenzoquat, dinitramine, diphenamid, IPC, napropamide, penoxalin, triffuralin, and U-27267. PMID:585583

  2. Herbicide interchange between a stream and the adjacent alluvial aquifer

    USGS Publications Warehouse

    Wang, W.; Squillace, P.

    1994-01-01

    Herbicide interchange between a stream and the adjacent alluvial aquifer and quantification of herbicide bank storage during high streamflow were investigated at a research site on the Cedar River flood plain, 10 km southeast of Cedar Rapids, Iowa. During high streamflow in March 1990, alachlor, atrazine, and metolachlor were detected at concentrations above background in water from wells as distant as 20, 50, and 10 m from the river's edge, respectively. During high streamflow in May 1990, alachlor, atrazine, cyanazine, and metolachlor were detected at concentrations above background as distant as 20, 50, 10, and 20 m from the river's edge, respectively. Herbicide bank storage took place during high streamflow when hydraulic gradients were from the river to the alluvial aquifer and the laterally infiltrating river water contained herbicide concentrations larger than background concentrations in the aquifer. The herbicide bank storage can be quantified by multiplying herbicide concentration by the "effective area" that a well represented and an assumed porosity of 0.25. During March 1990, herbicide bank storage values were calculated to be 1.7,79, and 4.0 mg/m for alachlor, atrazine, and metolachlor, respectively. During May 1990, values were 7.1, 54, 11, and 19 mg/m for alachlor, atrazine, cyanazine, and metolachlor, respectively. ?? 1994 American Chemical Society.

  3. Adsorption of sugar beet herbicides to Finnish soils.

    PubMed

    Autio, Sari; Siimes, Katri; Laitinen, Pirkko; Rämö, Sari; Oinonen, Seija; Eronen, Liisa

    2004-04-01

    Three sugar beet herbicides, ethofumesate, phenmedipham and metamitron, are currently used on conventional sugar beet cultivation, while new varieties of herbicide resistant (HR) sugar beet, tolerant of glyphosate or glufosinate-ammonium, are under field testing in Finland. Little knowledge has so far been available on the adsorption of these herbicides to Finnish soils. The adsorption of these five herbicides was studied using the batch equilibrium method in 21 soil samples collected from different depths. Soil properties like organic carbon content, texture, pH and partly the phosphorus and oxide content of the soils were tested against the adsorption coefficients of the herbicides. In general, the herbicides studied could be arranged according to their adsorption coefficients as follows: glyphosate>phenmedipham>ethofumesate approximately glufosinate-ammonium>metamitron, metamitron meaning the highest risk of leaching. None of the measured soil parameters could alone explain the adsorption mechanism of these five herbicides. The results can be used in model assessments of risk for leaching to ground water resulting from weed control of sugar beet in Finland. PMID:14761694

  4. Molecular and phenotypic characterization of Als1 and Als2 mutations conferring tolerance to acetolactate synthase herbicides in soybean

    PubMed Central

    Walter, Kay L; Strachan, Stephen D; Ferry, Nancy M; Albert, Henrik H; Castle, Linda A; Sebastian, Scott A

    2014-01-01

    BACKGROUND Sulfonylurea (SU) herbicides are effective because they inhibit acetolactate synthase (ALS), a key enzyme in branched-chain amino acid synthesis required for plant growth. A soybean line known as W4-4 was developed through rounds of seed mutagenesis and was demonstrated to have a high degree of ALS-based resistance to both post-emergence and pre-emergence applications of a variety of SU herbicides. This report describes the molecular and phenotypic characterization of the Als1 and Als2 mutations that confer herbicide resistance to SUs and other ALS inhibitors. RESULTS The mutations are shown to occur in two different ALS genes that reside on different chromosomes: Als1 (P178S) on chromosome 4 and Als2 (W560L) on chromosome 6 (P197S and W574L in Arabidopsis thaliana). CONCLUSION Although the Als1 and Als2 genes are unlinked, the combination of these two mutations is synergistic for improved tolerance of soybeans to ALS-inhibiting herbicides. © 2014 DuPont Pioneer. Pest Management Science published by JohnWiley & Sons Ltd on behalf of Society of Chemical Industry. PMID:24425499

  5. Herbicide contamination and dispersion pattern in lowland springs.

    PubMed

    Laini, Alex; Bartoli, Marco; Lamastra, Lucrezia; Capri, Ettore; Balderacchi, Matteo; Trevisan, Marco

    2012-11-01

    Herbicides reduce the diversity of flora and fauna in freshwater ecosystems and also contaminate groundwater due to leaching. Herbicide contamination can be a serious threat for all groundwater-dependent ecosystems (GDE), altering their chemical and biological quality. Successful management to protect GDE is dependent on detailed knowledge of the hydrogeological and hydrochemical features of the surrounding environment. We consider the possible diffuse contamination by herbicides of groundwater and of GDE as lowland springs, semi-artificial ecosystems with elevated biodiversity. The main objectives of the present work were thus: (1) to map herbicide contamination in lowland springs, (2) to evaluate the potential risk for biota and (3) to quantify the extent of the area from which the herbicide use can affect the water quality of lowland springs. In June and August 2009, nearly 23 springs within the Po River Plain (Northern Italy) were sampled and analyzed for five herbicides used to control weeds in maize. Hydrogeological properties, half-lives of the herbicides and their concentrations in both groundwater and springs were used to quantify the area from which the contamination could originate. Such evaluation was performed by means of GIS techniques. Terbuthylazine were the only herbicide found, together with its metabolite desethylterbuthylazine. In 16 out of 84 measurements, their concentrations were above the threshold for drinking water; however, they were always below the ecotoxicological end-points of aquatic flora and fauna. Spatial analyses reveal that the theoretical area from which herbicides can contaminate spring water is within a distance varying between a few and 1800 m. Our findings indicate that conservation plans should focus on the fields adjacent to or surrounding the springs and should address the optimization of irrigation practices, restoration of buffer strips, crop rotation and in general more sustainable agricultural practices in the

  6. Factors affecting weed control with pelargonic acid

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pelargonic acid is a fatty acid naturally occurring in many plants and animals, and present in many foods we consume. Producers and researchers are interested in pelargonic acid as a broad-spectrum post-emergence or burn-down herbicide. The objective of this research was to determine the effect of p...

  7. Triazine herbicide resistance in the photosynthetic bacterium Rhodopseudomonas sphaeroides

    SciTech Connect

    Brown, A.E.; Gilbert, C.W.; Guy, R.; Arntzen, C.J.

    1984-10-01

    The photoaffinity herbicide azidoatrazine (2-azido-4-ethylamino-6-isopropylamino-s-triazine) selectively labels the L subunit of the reaction center of the photosynthetic bacterium Rhodopseudomonas sphaeroides. Herbicide-resistant mutants retain the L subunit and have altered binding properties for methylthio- and chloro-substituted triazines as well as altered equilibrium constants for electron transfer between primary and secondary electron acceptors. We suggest that a subtle alteration in the L subunit is responsible for herbicide resistance and that the L subunit is the functional analog of the 32-kDa Q/sub B/ protein of chloroplast membranes. 42 references, 6 figures, 1 table.

  8. Determination of the herbicide fluroxypyr in oil matrices.

    PubMed

    Muhamad, Halimah B; Ai, Tan Yew; Sahid, Ismail B

    2008-02-01

    The purpose of this study was to develop a method for the determination of fluroxypyr (4-amino-3,5-dichloro-6-fluro2-pyridyloxyacetic acid) residue in palm oil namely crude palm oil (CPO) and crude palm kernel oil (CPKO). The method involves the extraction of the herbicide from the oil matrix followed by low temperature precipitation and finally quantification of the residues using the high performance liquid chromatography (HPLC). The extraction efficiency of the method was evaluated by conducting recovery studies. The recovery of fluroxypyr from the fortified CPO samples ranged from 78%-111% with the relative values for the coefficient of variation ranging from 1.4 to 8.6%. Furthermore, the recovery of fluroxypyr from the spiked CPKO samples ranged from 91-107% with the relative values for the coefficient of variation ranging from 0.6 to 4.5%. The minimum detection limit of fluroxypyr in CPO and CPKO was 0.05 microg/g. The method was used to determine fluroxypyr residues from the field-treated samples of CPO and CPKO. When fluroxypyr was used for weed control in oil palm plantations no residue was detected in CPO and CPKO irrespective of the sampling interval and the dosage applied at the recommended or double the manufacturer's recommended dosage. PMID:18246505

  9. Removal of clomazone herbicide from a synthetic effluent by electrocoagulation.

    PubMed

    Benincá, Cristina; Vargas, Fernanda T; Martins, Manoel L; Gonçalves, Fábio F; Vargas, Rodrigo P; Freire, Flavio B; Zanoelo, Everton F

    2016-01-01

    The aim of this work was to investigate the kinetics of removal of clomazone herbicide from an aqueous solution by electrocoagulation. The experiments were performed in a cylindrical batch reactor with six aluminum electrodes in monopolar mode, arranged in series and connected to a digital DC power. The aqueous solution (tap water + clomazone) with initial pH close to 7.9 was always treated at ambient temperature (≈20 °C) and atmospheric pressure for 5,400 s. For a confidence level of 95% the rate constant of electrocoagulation and the efficiency of removal of clomazone at equilibrium were 2.1 × 10(-3) ± 0.5 × 10(-3) s(-1) and 97.7 ± 2.2%, respectively. The final chemical oxygen demand was 88% lower than that measured initially, while turbidity and apparent color were totally removed from the synthetic solution at a rate close to that of formation of aluminum hydroxides. Some reaction intermediates, such as benzonitrile-2-chloro and 2-chloro-hex-2,4-diene-1,6-dioic-acid determined by gas chromatography mass spectrometry (GC-MS) analysis, explain the ratio of equilibrium to initial total organic carbon approximately between 0.6 and 0.8 at a probability of 95%. PMID:27332840

  10. Pelargonic acid - a potential organic aquatic herbicide for duckweed management

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Duckweed (Lemna spp.) are small, free floating aquatic plants that flourish on stagnant, or slow moving, water surfaces throughout the continental U.S. Members of the genus are among the smallest flowering plants, providing food for fish and fowl, but their aggressive growth and invasive habit make...

  11. Characterization of a strain of Sphingobacterium sp. and its degradation to herbicide mefenacet.

    PubMed

    Ye, Yang-fang; Min, Hang; Du, Yu-feng

    2004-01-01

    A bacterium (designated strain Y1) degrading acetanilide herbicide mefenacet was isolated from aerobic sludge. Based on the analyses of partial 16S rRNA gene, cellular fatty acid and BIOLOG-GN, and general physiological and biochemical characteristics, strain Y1 was identified as Sphingobacterium multivolum. Strain Y1 was able to degrade mefenacet used as sources of carbon and energy. Degradation of mefenacet was accompanied by producing the metabolites N-methylaniline and an unidentified compound with molecular weight 205, indicating a metabolic pathway of mefenacet initiated by hydrolysis of amido bond. PMID:15137667

  12. Genetic mapping of non-target site resistance to a sulfonylurea herbicide (Envoke®) in Upland cotton (Gossypium hirsutum L.)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Acetolactate synthase (ALS) is responsible for a rate limiting step in the synthesis of essential branched chain amino acids. Resistance to ALS-inhibiting herbicides, such as trifloxysulfuron sodium (Envoke®), can be due to mutations in the target gene itself. Alternatively, plants may exhibit herb...

  13. Compositional equivalence of DAS-444Ø6-6 (AAD-12 + 2mEPSPS + PAT) herbicide-tolerant soybean and nontransgenic soybean.

    PubMed

    Lepping, Miles D; Herman, Rod A; Potts, Brian L

    2013-11-20

    Soybeans from transgenic event DAS-444Ø6-6 are the first to express three proteins that provide tolerance to broad-spectrum herbicides. DAS-444Ø6-6 soybean expresses the aryloxyalkanoate dioxygenase-12 (AAD-12) enzyme from the soil bacterium Delftia acidovorans , which provides tolerance to the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D); the double-mutant 5-enolpyruvylshikimate-3-phosphate synthase (2mEPSPS) enzyme encoded by a modified version of the epsps gene from maize ( Zea mays ), which provides tolerance to the herbicide glyphosate; and the phosphinothricin acetyltransferase (PAT) enzyme from Streptomyces viridochromogenes , which provides tolerance to the herbicide glufosinate. The purpose of this study was to determine if the nutrient and antinutrient composition of forage and grain from DAS-444Ø6-6 soybean are similar to those of nontransgenic soybean. Forage was analyzed for proximates, fiber, and minerals; grain analyses further included vitamins, amino acid and fatty acid profiles, and antinutrients and bioactive components (lectin, phytic acid, raffinose, stachyose, trypsin inhibitor, and isoflavones). Results indicate that DAS-444Ø6-6 soybean is compositionally equivalent to nontransgenic soybean. Findings are consistent with similar studies for other input traits, as endogenous plant metabolic pathways that influence composition are expected to be less affected by transgenesis compared with traditional plant-breeding methods. PMID:24191699

  14. The herbicide Glyphosate affects nitrification in the Elbe estuary, Germany

    NASA Astrophysics Data System (ADS)

    Sanders, Tina; Lassen, Stephan

    2015-04-01

    The Elbe River is one of the biggest European rivers discharging into the North Sea. It also transports high amounts of nutrients and pollutants like pesticides. Important source regions of both nutrients and pollutants are located within the river catchment, which is dominated by agricultural land-use. From these agricultural soils, pesticides can be carried via the river and estuary into the North Sea. Glyphosate (N-(phosphonomethyl) glycine) is the most commonly used herbicide worldwide and mainly used to regulate unwanted plant growth and for the expedition of crop ripening. In Germany, ~ 6000 tons of glyphosate are applied yearly in agriculture and private use. Glyphosate is degradable by microorganisms and has a half-life in water of 35 to 60 days. This herbicide specifically inhibits 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS), an enzyme that catalyzes the biosynthesis of essential aromatic amino acids in plants, fungi, and bacteria. Nitrifying bacteria, which play an important role in the internal nitrogen cycling in the Elbe estuary, also possess this enzyme. The aim of our study was to quantify the concentration of glyphosate in water and sediment samples of the Elbe to get an overview about relevant environmental levels and to assess the impact of glyphosate on inhibition of nitrifying activities. To quantify the effect of glyphosate on nitrification activity, natural samples as well as pure cultures of Nitrosomonas europea (strain Nm50) were incubated with different concentrations of glyphosate over a period of some weeks. The nitrifying activity was determined according to changes of the nitrite and nitrate concentration as well as the cell number. Glyphosate was detectable in water and sediment samples in the Elbe estuary with up to 5 ppb mainly in the Port of Hamburg region. In both incubation experiments an inhibiting effect of glyphosate on nitrification could be shown. The incubated natural water sample was affected by a glyphosate

  15. Herbicides in ground water beneath Nebraska's Management Systems Evaluation Area.

    PubMed

    Spalding, Roy F; Exner, Mary E; Snow, Daniel D; Cassada, David A; Burbach, Mark E; Monson, Stephen J

    2003-01-01

    Profiles of ground water pesticide concentrations beneath the Nebraska Management Systems Evaluation Area (MSEA) describe the effect of 20 yr of pesticide usage on ground water in the central Platte Valley of Nebraska. During the 6-yr (1991-1996) study, 14 pesticides and their transformation products were detected in 7848 ground water samples from the unconfined water table aquifer. Triazine and acetamide herbicides applied on the site and their transformation products had the highest frequencies of detection. Atrazine [6-chloro-N-ethyl-N'-(1-methylethyl)-1,3,5-triazine-2,4,-diamine] concentrations decreased with depth and ground water age determined with 3H/3He dating techniques. Assuming equivalent atrazine input during the past 20 yr, the measured average changes in concentration with depth (age) suggest an estimated half-life of >10 yr. Hydrolysis of atrazine and deethylatrazine (DEA; 2-chloro-4-amino-6-isopropylamino-s-triazine) to hydroxyatrazine [6-hydroxy-N-ethyl-N'-(1-methylethyl)-1,3,5-triazine-2,4-diamine] appeared to be the major degradation route. Aqueous hydroxyatrazine concentrations are governed by sorption on the saturated sediments. Atrazine was detected in the confined Ogallala aquifer in ultra-trace concentrations (0.003 microg L(-1)); however, the possibility of introduction during reverse circulation drilling of these deep wells cannot be eliminated. In fall 1997 sampling, metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl) acetamide] was detected in 57% of the 230 samples. Metolachlor oxanilic acid [(2-ethyl-6-methylphenyl)(2-methoxy-1-methylethyl) amino]oxo-acetic acid] was detected in most samples. In ground water profiles, concentrations of metolachlor ethane sulfonic acid [2-[(ethyl-6-methylphenyl)(2-methoxy-1-methylethyl)amino]-2-oxo-ethanesulfonic acid] exceeded those of deethylatrazine. Alachlor [2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl)acetamide] was detected in <1% of the samples; however, alachlor

  16. A silviculture application of the glyphosate-based herbicide VisionMAX to wetlands has limited direct effects on amphibian larvae.

    PubMed

    Edge, Christopher B; Thompson, Dean G; Hao, Chunyan; Houlahan, Jeff E

    2012-10-01

    Herbicides are commonly used in agriculture and silviculture to reduce interspecific competition among plants and thereby enhance crop growth, quality, and volume. Internationally, glyphosate-based herbicides are the most widely used herbicides in both of these sectors. Laboratory and mesocosm studies have demonstrated that some formulations are toxic to amphibian larvae below concentrations that approximate predicted maximal or "worst-case" exposure scenarios. However, field studies have not found evidence of toxicity at these concentrations. The authors conducted a replicated field experiment involving 10 naturalized wetlands split in half with an impermeable plastic barrier to assess the direct toxicity of a glyphosate formulation commonly used in silviculture (VisionMAX™). The herbicide formulation was applied directly to the surface of one side of each wetland at one of two target aqueous exposure rates (high = 2,880, low = 550 µg acid equivalents [a.e.]/L), and the other side was left as an untreated control. The survival and growth of green frog larvae (Lithobates clamitans) were assessed for two years following herbicide treatment. The herbicide did not have a negative impact on survival or growth of L. clamitans larvae at either treatment level. In fact, mean larval abundance was typically greater in the treated sides than in control sides within the year of herbicide application. These results indicate that typical silviculture use of VisionMAX poses negligible risk to larval amphibians, likely because the combined effects of sorption and degradation in natural wetlands limit the exposure magnitude and duration. PMID:22833320

  17. Detection of bromacil herbicide in ponderosa pine

    SciTech Connect

    Ferenbaugh, R.W.; Spall, W.D.; LaCombe, D.M.

    1981-08-01

    Bromacil is a substituted uracil herbicide, 5-bromo-3-sec-butyl-6-methyluracil. Because it is readily absorbed through the root system of plants, bromacil usually is applied to the soil as an aqueous solution or suspension during or just before periods of active plnt growth. Until recently, bromacil was used as part of a vegetation control program along roadways at the Los Alamos National Laboratory. The prescribed method of application was to spray a four-foot wide strip of bromacil solution along the edges of roadways with a spray-bar. During the late spring and early summer of 1978, bromacil was determined to be the proximate cause of damage to numerous trees at substantial distances away from roadways at Los Alamos. This paper describes the investigation that was undertaken to determine the cause of the tree mortality.

  18. [Microbial degradation of glyphosate herbicides (review)].

    PubMed

    Sviridov, A V; Shushkova, T V; Ermakova, I T; Ivanova, E V; Epiktetov, D O; Leont'evskii, A A

    2015-01-01

    This review analyzes the issues associated with biodegradation of glyphosate (N-(phosphonomethyl)glycine), one of the most widespread herbicides. Glyphosate can accumulate in natural environments and can be toxic not only for plants but also for animals and bacteria. Microbial transformation and mineralization ofglyphosate, as the only means of its rapid degradation, are discussed in detail. The different pathways of glyphosate catabolism employed by the known destructing bacteria representing different taxonomic groups are described. The potential existence of alternative glyphosate degradation pathways, apart from those mediated by C-P lyase and glyphosate oxidoreductase, is considered. Since the problem of purifying glyphosate-contaminated soils and water bodies is a topical issue, the possibilities of applying glyphosate-degrading bacteria for their bioremediation are discussed. PMID:26027353

  19. CACODYLIC ACID (DMAV): METABOLISM AND CARCINOGENIC MODE OF ACTION

    EPA Science Inventory

    The cacodylic acid (DMAV) issue paper discusses the metabolism and pharmacokinetics of the various arsenical chemicals; evaluates the appropriate dataset to quantify the potential cancer risk to the organic arsenical herbicides; provides an evaluation of the mode of carcinogenic...

  20. Response of avian communities to herbicide-induced vegetation changes

    USGS Publications Warehouse

    Morrison, M.L.; Meslow, E.C.

    1984-01-01

    The relationships between avian communities and herbicide modification of vegetation were analyzed on early-growth clear-cuts in western Oregon that had received phenoxy herbicide treatment 1 or 4 years previously. For both 1 and 4 years post-spray, vegetation development was greater in the third height interval (> 3.0 m) on untreated sites. All measures of vegetative diversity on untreated sites exceeded those on treated sites. Overall density and diversity of birds were similar between treated and untreated sites. Several bird species altered their foraging behavior on treated sites, i.e., birds using deciduous trees increased use of shrubs on treated sites. The primary effect of herbicide application was a reduction in the complexity of vegetation, a condition due primarity to the removal of deciduous trees. Small patches of deciduous trees scattered in clear-cuts treated with phenoxy herbicides can maintain an avian community similar to that on untreated sites.

  1. SWEET CORN CULTIVAR INFLUENCES BIOLOGICALLY EFFECTIVE HERBICIDE DOSE [ABSTRACT

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Competitive crop cultivars are considered a component of integrated weed management systems; however specific knowledge of interactions among crop cultivars and other management tactics, such as biologically effective herbicide dose, is limited. Observed variation in crop tolerance and weed supp...

  2. Investigation of Anaerobic Herbicide Degradation in Agricultural Soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Anaerobic microbial pesticide degradation has received little attention, particularly in agricultural soils that receive routine inputs of halogenated herbicides. Seasonal rainfall in many regions can produce zones of periodic anaerobiosis in soil. Redox gradients within soil aggregates can also for...

  3. Herbicidal agents from actinomycetes against selected crop plants and weeds.

    PubMed

    Dhanasekaran, Dharumadurai; Thajuddin, Nooruddin; Panneerselvam, Annamalai

    2010-04-01

    About 64 total actinomycetes were isolated from various coastal soils. Sixteen actinomycete isolates were screened for herbicidal principles. Out of these, five potent isolates were selected for characterisation and identification. Based on their morphological, biochemical and physiological characteristics, the actinomycete isolates were identified as Glyomyces, Saccharomonospra and Streptomyces sp. The Streptomycetes isolates were tested for herbicidal principles by germination inhibition assay. About 10 crop seeds were tested for herbicidal activity with Streptomycetes isolates. The crop seeds did not show growth inhibition. Four weed seeds were tested for herbicidal activity with Streptomyces isolates. Streptomyces inhibits the growth of Echinochilora crusgalli, but it could not inhibit the growth of Echinochilora colonum, Parthenium sp., or Ageratum conizoites. The present study concludes that Streptomyces isolates will be a bioherbicide against E. crusgalli. Further study is required to confirm the activity of Streptomyces isolates against E. crusgalli under field conditions. PMID:20182949

  4. Impacts of forest herbicides on wildlife: Toxicity and habitat alteration

    USGS Publications Warehouse

    Morrison, M.L.; Meslow, E.C.

    1983-01-01

    This paper begins with a review of both laboratory and field studies on tbe possible direct toxic effects of herbicides on terrestrial vertebrates, primarily birds and mammals. Alteration of the palatability of forage and changes in reproductive success are also discussed. Emphasis is placed on the use of herbicides in forestry; studies dealing with agricultural systems are referenced where appropriate. The indirect effects of herbicides on wildlife-habitat are then conceptualized and quantified using data from a 3-year study on effects of phenoxy and glyphosate herbicides on bird and small mammal communities in western Oregon. Data on density and habitat use are presented and compared with data available from other geographic regions.

  5. Commercial Herbicides Can Trigger the Oxidative Inactivation of Acetohydroxyacid Synthase.

    PubMed

    Lonhienne, Thierry; Nouwens, Amanda; Williams, Craig M; Fraser, James A; Lee, Yu-Ting; West, Nicholas P; Guddat, Luke W

    2016-03-18

    Acetohydroxyacid synthase (AHAS) inhibitors are highly successful commercial herbicides. New kinetic data show that the binding of these compounds leads to reversible accumulative inhibition of AHAS. Crystallographic data (to a resolution of 2.17 Å) for an AHAS-herbicide complex shows that closure of the active site occurs when the herbicidal inhibitor binds, thus preventing exchange with solvent. This feature combined with new kinetic data shows that molecular oxygen promotes an accumulative inhibition leading to the conclusion that the exceptional potency of these herbicides is augmented by subversion of an inherent oxygenase side reaction. The reactive oxygen species produced by this reaction are trapped in the active site, triggering oxidation reactions that ultimately lead to the alteration of the redox state of the cofactor flavin adenine dinucleotide (FAD), a feature that accounts for the observed reversible accumulative inhibition. PMID:26924714

  6. Oxidative damage mediated by herbicides on yeast cells.

    PubMed

    Braconi, Daniela; Possenti, Silvia; Laschi, Marcella; Geminiani, Michela; Lusini, Paola; Bernardini, Giulia; Santucci, Annalisa

    2008-05-28

    Agricultural herbicides are among the most commonly used pesticides worldwide, posing serious concerns for both humans, exposed to these chemicals through many routes, and the environment. To clarify the effects of three herbicides as commercial formulations (namely, Pointer, Silglif, and Proper Energy), parameters related to oxidative issues were investigated on an autochthonous wine yeast strain. It was demonstrated that herbicides were able to affect the enzymatic activities of catalase and superoxide dismutase, as well as to induce carbonylation and thiol oxidation as post-translational modifications of proteins. Saccharomyces cerevisiae is an optimal model system to study responses to xenobiotics and oxidative stress. Thus, the results obtained could further the understanding of mechanisms underlying the toxicity of herbicides. PMID:18442254

  7. Ragweed Parthenium (Parthenium hysterophorus) Control with Preemergence and Postemergence Herbicides

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Field and greenhouse experiments were conducted during 2005 and 2006 at Stoneville, MS to determine control of ragweed parthenium with several preemergence (PRE) and postemergence (POST) herbicides registered for use in corn, cotton, peanut, rice, and soybean. Norflurazon, pendimethalin, clomazone, ...

  8. Combined herbicide and saline stress differentially modulates hormonal regulation and antioxidant defense system in Oryza sativa cultivars.

    PubMed

    Islam, Faisal; Ali, Basharat; Wang, Jian; Farooq, Muhammad A; Gill, Rafaqat A; Ali, Shafaqat; Wang, Danying; Zhou, Weijun

    2016-10-01

    Plants are simultaneously exposed to a combination of biotic and abiotic stresses in field conditions. Crops respond to the combined stress in a unique way which cannot be understood by extrapolating the results of individual stress. In the present study, effects of individual and combined stress of herbicide (2,4-dichlorophenoxyacetic acid) and salinity (NaCl) on two Oryza sativa cultivars (ZJ 88 and XS 134) were investigated. Both herbicide and saline stress affected the plant growth differentially and produced oxidative stress in rice cultivars. Interestingly, the combination of herbicide and salinity showed a significant protection to both rice cultivars by reducing ROS (H2O2, O2(-)) and lipid peroxidation through modulation of enzymatic (SOD, POD, CAT and APX) and non-enzymatic (TSP, sugars, phenolic and proline) antioxidants. In addition, active regulation of transcript levels of genes encoding Na(+) and K(+) (OsHKT1;5, OsLti6a,b, OsHKT2;1, OsSOS1, OsCNGC1, OsNHX1 and OsAKT1) transporter proteins reduced sodium and enhanced potassium accumulation under combined stress, resulted a better growth and ionic homeostasis in both rice cultivars. The production of ABA and IAA was significantly higher in cultivar XS 134 compared to cultivar ZJ 88 under control conditions. However, combined herbicide and saline stress enhanced the accumulation of phytohormones (IAA and ABA) and transcription of ethylene in cultivar ZJ 88, which might be one of the factors responsible for poor salt tolerance in sensitive cultivar. These findings indicated that herbicide application under saline stress confers tolerance to salinity in rice cultivars, likely by reducing oxidative damage, modulating mineral absorption, upgradation of antioxidant defense and by dynamic regulation of key genes involved in Na(+) and K(+) homeostasis in plants. PMID:27258572

  9. Allergic contact dermatitis due to a herbicide (barban).

    PubMed Central

    Hogan, D J; Lane, P R

    1985-01-01

    Canadian farmers are using increasing amounts of herbicides. Often they do not use adequate skin protection. Two cases of severe allergic contact dermatitis due to the herbicide barban are described. Patch testing with various substances, including barban, confirmed the diagnosis. Sensitization studies in guinea pigs and in one of the authors showed that barban is a potent sensitizer. It is recommended that if skin contact with barban occurs the skin be washed immediately with soap and water. Images Fig. 1 PMID:3971254

  10. Protoporphyrin IX Content Correlates with Activity of Photobleaching Herbicides

    PubMed Central

    Becerril, Jose M.; Duke, Stephen O.

    1989-01-01

    Several laboratories have demonstrated recently that photobleaching herbicides such as acifluorfen and oxadiazon cause accumulation of protoporphyrin IX (PPIX), a photodynamic pigment capable of herbicidal activity. We investigated, in acifluorfen-treated tissues, the in vivo stability of PPIX, the kinetics of accumulation, and the correlation between concentration of PPIX and herbicidal damage. During a 20 hour dark period, PPIX levels rose from barely detectable concentrations to 1 to 2 nanomoles per 50 cucumber (Cucumis sativus L.) cotyledon discs treated with 10 micromolar acifluorfen. When placed in 500 micromoles per square meter per second PAR, PPIX levels decayed logarithmically, with an initial half-life of about 2.5 hours. PPIX levels at each time after exposure to light correlated positively with the cellular damage that occurred during the following 1 hour in both green and yellow (tentoxin-treated) cucumber cotyledon tissues. PPIX levels in discs incubated for 20 hours in darkness correlated positively with the acifluorfen concentration in which they were incubated. In cucumber, the level of herbicidal damage caused by several p-nitrodiphenyl other herbicides, a p-chlorodiphenylether herbicide, and oxadiazon correlated positively with the amount of PPIX induced to accumulate by each of the herbicide treatments. Similar results were obtained with acifluorfen-treated pigweed and velvetleaf primary leaf tissues. In cucumber, PPIX levels increased within 15 and 30 minutes after exposure of discs to 10 micromolar acifluorfen in the dark and light, respectively. These data strengthen the view that PPIX is responsible for all or a major part of the photobleaching activity of acifluorfen and related herbicides. PMID:16666869

  11. Impact of dry-wet and freeze-thaw events on pesticide mineralizing populations and their activity in wetland ecosystems: A microcosm study.

    PubMed

    Vandermeeren, Pieter; Baken, Stijn; Vanderstukken, Ruben; Diels, Jan; Springael, Dirk

    2016-03-01

    Riparian wetlands are proposed to mitigate diffuse pollution of surface water by pesticides in agricultural landscapes. Wetland ecosystems though are highly dynamic environments and seasonal disturbances such as freezing and drying can affect microbial population sizes in the sediment and their functionality including pesticide biodegradation, which has hardly been studied. This study examined the effect of artificially induced dry-wet or freeze-thaw events on the mineralization of the pesticides isoproturon (IPU) and 2-methoxy-4-chlorophenoxy acetic acid (MCPA) in wetland microcosms, either without or with prior enrichment of IPU/MCPA degrading populations. Without prior enrichment, mineralization of IPU and MCPA was significantly reduced after exposure to especially freeze-thaw events, as evidenced by lower mineralization rates and longer lag times compared to non-exposed microcosms. However, herbicide mineralization kinetics correlated poorly with cell numbers of herbicide mineralizers as estimated by a most probable number (MPN) approach and the number of IPU and MCPA mineralizers was unexpectedly higher in freeze-thaw and dry-wet cycle exposed setups compared to the control setups. This suggested that the observed effects of season-bound disturbances were due to other mechanisms than decay of pesticide mineralizers. In addition, in systems in which the growth of pesticide mineralizing bacteria was stimulated by amendment of IPU and MCPA, exposure to a freeze-thaw or dry-wet event only marginally affected the herbicide mineralization kinetics. Our results show that season bound environmental disturbances can affect pesticide mineralization kinetics in wetlands but that this effect can depend on the history of pesticide applications. PMID:26714290

  12. Simultaneous detection and quantitation of highly water-soluble herbicides in serum using ion-pair liquid chromatography-tandem mass spectrometry.

    PubMed

    Wang, Kuang-Chuan; Chen, Shih-Ming; Hsu, Jung-Fa; Cheng, Sheaw-Guey; Lee, Ching-Kuo

    2008-12-15

    We report the simultaneous screening of highly polar, water-soluble, and less-volatile herbicides, including glyphosate, glufosinate, paraquat, and diquat, in serum using liquid chromatography-mass spectrometry. The herbicides were separated by solid-phase extraction using a Strata-XC cartridge. A heptafluorobutyric acid solution was chosen as the mobile phase for ion-pair liquid chromatography. Mass spectrometry was used for analysis and was optimized for operation in the positive mode for all analytes. The serum specimens were screened for the presence of the herbicides at the following concentrations: 5 ng/mL for glyphosate, 2 ng/mL for glufosinate, 1 ng/mL for diquat, and 5 ng/mL for paraquat. This is the first report on the simultaneous detection of these compounds. PMID:19022710

  13. Work plan for determining the occurrence of glyphosate, its transformation product AMPA, other herbicide compounds, and antibiotics in midwestern United States streams, 2002

    USGS Publications Warehouse

    Battaglin, W.A.; Thurman, E.M.; Kolpin, D.W.; Scribner, E.A.; Sandstrom, M.W.; Kuivila, K.M.

    2003-01-01

    The objective of this study is to determine the distribution of glyphosate and its primary transformation product aminomethylphosphonic acid (AMPA) in midwestern streams during post-application and harvest-season runoff events. Water samples will be collected in 2002 during two post-herbicide-application runoff events and one harvest-season runoff event from 53 sites on streams in the Midwestern United States. All samples will be analyzed at the U.S. Geological Survey Organic Geochemistry Research Laboratory in Lawrence, Kansas, for glyphosate and 20 other herbicides. Samples will also be analyzed for a glyphosate transformation product (AMPA) and 26 other herbicide transformation products, using GC/MS or HPLC/MS. Selected samples will be analyzed for 36 antibiotics or antibiotic transformational products. Results from this study will represent the first broad-scale investigation of glyphosate and AMPA in U.S. water resources.

  14. Mobility and efficacy of 2,4-D herbicide from slow-release delivery systems based on organo-zeolite and organo-bentonite complexes.

    PubMed

    Shirvani, Mehran; Farajollahi, Edris; Bakhtiari, Somayeh; Ogunseitan, Oladele A

    2014-01-01

    This research aimed to develop slow-release formulations (SRFs) of 2,4-dichlorophenoxyacetic acid (2,4-D) using zeolite and bentonite minerals modified with cetyltrimethylammonium (CTMA) surfactant. Adsorption-desorption, greenhouse bioassay and column experiments were carried out to assess the potential of the SRFs to control weeds while reducing the herbicide leaching losses to deep layers of soil. The results showed that only 6.5 mmol 2,4-D kg(-1) was retained by Na-bent, and the herbicide was not adsorbed by Na-zeol at all. The surface modification with CTMA surfactant, however, improved the 2,4-D adsorption capacity of the zeolite and bentonite up to 207.5 and 415.8 mmol kg(-1), respectively. The synthesized organo-minerals slowly released the retained 2,4-D discharging 22 to 64% of the adsorbed 2,4-D to the solution phase within 7 days. The SRFs significantly (P = 0.05) reduced the herbicide mobility within the soil columns keeping a great portion of the herbicide active ingredient in the upper 5 cm soil layer. The SRFs were significantly (P = 0.05) as effective as the free technical herbicide in weed control without harming the ryegrass as the main plant. Therefore, the synthesized SRFs could be considered as useful tools for weed control in sustainable agriculture. PMID:24502212

  15. Simulating the dissipation of two herbicides using micro paddy lysimeters.

    PubMed

    Nhung, Dang Thi Tuyet; Phong, Thai Khanh; Watanabe, Hirozumi; Iwafune, Takashi; Thuyet, Dang Quoc

    2009-11-01

    A set of packed micro paddy lysimeters, placed in a greenhouse, was used to simulate the dissipation of two herbicides, simetryn and thiobencarb, in a controlled environment. Data from a field monitoring study in 2003, including the soil condition and water balances, were used in the simulation. The herbicides were applied and monitored over a period of 21 d. The water balances under two water management scenarios, intermittent irrigation management (AI) and continuous irrigation management (CI), were simulated. In the AI scenario, the pattern of herbicide dissipation in the surface water of the field were simulated, following the first-order kinetics. In the CI scenario, similarity was observed in most lysimeter and field concentrations, but there were differences in some data points. Dissipation curves of both herbicides in the surface water of the two simulated scenarios were not significantly different (P>0.05) from the field data except for intercept of the thiobencarb curve in the CI scenario. The distribution of simetryn and thiobencarb in the soil profile after simulation were also similar to the field data. The highest concentrations of both herbicides were found on the topsoil layer at 0-2.5 cm depth. Only a small amount of herbicides moved down to the deeper soil layers. Micro paddy lysimeters are thus a good alternative for the dissipation study of pesticides in the paddy environment. PMID:19811801

  16. Herbicidal treatments for control of Papaver somniferum L.

    PubMed

    Horowitz, M

    1980-01-01

    Fifty-five commercially available herbicides were evaluated for possible use to destroy illicit opium poppy crops (Papaver somniferum). In the first stage, herbicides were sprayed on poppy plants grown in containers. The following compounds killed poppy plants: (a) herbicides with typical foliar activity--amitrole, bromoxynil, 2,4-D, glyphosate, ioxynil and paraquat; and (b) herbicides with root and foliar activity--the triazines ametryn, atrazine, metribuzin, prometryn, simazine and terbutryn; the substituted ureas benzthiazuron, chloroxuron, diuron, fluometuron, linuron, methabenzthiazuron, neburon and phenobenzuron; and the miscellaneous compounds karbutilate, methazole, oxadiazon and pyrazon. Severe but sublethal injury was caused by cycloate, EPTC, molinate, pobulate, cacodylate + MSMA, ethofumesate, perfluidone and phenmedipham. Abnormal development of vegetative or reproductive parts of the plant was induced by benefin, butralin, dinitramine, pendimethalin, trifluralin, diphenamid, napropamide, dalapon and propham. Efficient herbicides with negligible persistence in soil at the doses applied were evaluated on poppy plants in the field at various stages of growth. Small plants were severely injured by 2,4-D, killed rapidly by bromoxynil, ioxynil, paraquat (in mixture + diquat), and more slowly by glyphosate and metribuzin. The resistance to herbicides increased with the age of the poppy plant. Severe damage with partial kill of developed plants was obtained with bromoxynil, ioxynil, glyphosate, and paraquat + diquat; the last treatment produced the fastest effect. PMID:6905769

  17. Surface water-ground water interaction: Herbicide transport into municipal collector wells

    USGS Publications Warehouse

    Verstraeten, Ingrid M.; Carr, J.D.; Steele, G.V.; Thurman, E.M.; Bastian, K.C.; Dormedy, D.F.

    1999-01-01

    During spring runoff events, herbicides in the Platte River are transported through an alluvial aquifer into collector wells located on an island in the river in 6 to 7 d. During two spring runoff events in 1995 and 1996, atrazine [2-chloro-4-ethylamino-6-isopropylamino-s-triazine] concentrations in water from these wells reached approximately 7 ??g/L, 70 times more than the background concentration in ground water. Concentrations of herbicides and metabolites in the collector wells generally were one-half to one-fifth the concentrations of herbicides in the river for atrazine, alachlor [2-chloro-2'-6'-diethyl-N-(methoxymethyl)-acetanilide], alachlor ethane-sulfonic acid (ESA) [2-((2,6-diethylphenyl) (methoxymethyl)amino)-2- oxoethane-sulfonic acid], metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N- (2-methoxy-1-methylethyl)acetamide], cyanazine [2-((4-chloro-6-(ethyl-amino)- 1,3,5 triazin-2-yl)-amino)-2-methylpropionitrile], and acetochlor [2-chloro- N-(ethoxymethyl)-N-(2-ethyl-6methyl-phenyl) acetamide], suggesting that 20 to 50% river water could be present in the water from the collector wells, assuming no degradation. The effect of the river on the quality of water from the collector wells can be reduced through selective management of horizontal laterals of the collector wells. The quality of the water from the collector wells is dependent on the (i) selection of the collector well used, (ii) number and selection of laterals used, (iii) chemical characteristics of the contaminant, and (iv) relative mixing of the Platte River and a major upstream tributary.

  18. Establishment of Bacterial Herbicide Degraders in a Rapid Sand Filter for Bioremediation of Phenoxypropionate-Polluted Groundwater.

    PubMed

    Feld, Louise; Nielsen, Tue Kjærgaard; Hansen, Lars Hestbjerg; Aamand, Jens; Albers, Christian Nyrop

    2016-02-01

    In this study, we investigated the establishment of natural bacterial degraders in a sand filter treating groundwater contaminated with the phenoxypropionate herbicides (RS)-2-(4-chloro-2-methylphenoxy)propanoic acid (MCPP) and (RS)-2-(2,4-dichlorophenoxy)propanoic acid (DCPP) and the associated impurity/catabolite 4-chlorophenoxypropanoic acid (4-CPP). A pilot facility was set up in a contaminated landfill site. Anaerobic groundwater was pumped up and passed through an aeration basin and subsequently through a rapid sand filter, which is characterized by a short residence time of the water in the filter. For 3 months, the degradation of DCPP, MCPP, and 4-CPP in the sand filter increased to 15 to 30% of the inlet concentration. A significant selection for natural bacterial herbicide degraders also occurred in the sand filter. Using a most-probable-number (MPN) method, we found a steady increase in the number of culturable phenoxypropionate degraders, reaching approximately 5 × 10(5) degraders per g sand by the end of the study. Using a quantitative PCR targeting the two phenoxypropionate degradation genes, rdpA and sdpA, encoding stereospecific dioxygenases, a parallel increase was observed, but with the gene copy numbers being about 2 to 3 log units higher than the MPN. In general, the sdpA gene was more abundant than the rdpA gene, and the establishment of a significant population of bacteria harboring sdpA occurred faster than the establishment of an rdpA gene-carrying population. The identities of the specific herbicide degraders in the sand filter were assessed by Illumina MiSeq sequencing of 16S rRNA genes from sand filter samples and from selected MPN plate wells. We propose a list of potential degrader bacteria involved in herbicide degradation, including representatives belonging to the Comamonadaceae and Sphingomonadales. PMID:26590282

  19. Establishment of Bacterial Herbicide Degraders in a Rapid Sand Filter for Bioremediation of Phenoxypropionate-Polluted Groundwater

    PubMed Central

    Feld, Louise; Nielsen, Tue Kjærgaard; Hansen, Lars Hestbjerg; Aamand, Jens

    2015-01-01

    In this study, we investigated the establishment of natural bacterial degraders in a sand filter treating groundwater contaminated with the phenoxypropionate herbicides (RS)-2-(4-chloro-2-methylphenoxy)propanoic acid (MCPP) and (RS)-2-(2,4-dichlorophenoxy)propanoic acid (DCPP) and the associated impurity/catabolite 4-chlorophenoxypropanoic acid (4-CPP). A pilot facility was set up in a contaminated landfill site. Anaerobic groundwater was pumped up and passed through an aeration basin and subsequently through a rapid sand filter, which is characterized by a short residence time of the water in the filter. For 3 months, the degradation of DCPP, MCPP, and 4-CPP in the sand filter increased to 15 to 30% of the inlet concentration. A significant selection for natural bacterial herbicide degraders also occurred in the sand filter. Using a most-probable-number (MPN) method, we found a steady increase in the number of culturable phenoxypropionate degraders, reaching approximately 5 × 105 degraders per g sand by the end of the study. Using a quantitative PCR targeting the two phenoxypropionate degradation genes, rdpA and sdpA, encoding stereospecific dioxygenases, a parallel increase was observed, but with the gene copy numbers being about 2 to 3 log units higher than the MPN. In general, the sdpA gene was more abundant than the rdpA gene, and the establishment of a significant population of bacteria harboring sdpA occurred faster than the establishment of an rdpA gene-carrying population. The identities of the specific herbicide degraders in the sand filter were assessed by Illumina MiSeq sequencing of 16S rRNA genes from sand filter samples and from selected MPN plate wells. We propose a list of potential degrader bacteria involved in herbicide degradation, including representatives belonging to the Comamonadaceae and Sphingomonadales. PMID:26590282

  20. Determination of the herbicide glyphosate and its metabolite in biological specimens by gas chromatography-mass spectrometry. A case of poisoning by roundup herbicide.

    PubMed

    Hori, Yasushi; Fujisawa, Manami; Shimada, Kenji; Hirose, Yasuo

    2003-04-01

    In Japan, poisonings by the glyphosate (GLYP)-containing herbicide Roundup and the gluphosinate (GLUF)-based herbicide BASTA have been increasing since about 1987. We applied the gas chromatography-mass spectrometry (GC-MS) method of analysis, on which we have already reported in regard to the determination of the blood serum level of GLUF and its metabolite, for the determination of serum and urinary levels of GLYP and its metabolite aminomethyl phosphonic acid (AMPA). Derivatization using N-methyl-N-(tert-butyldimethylsilyl) trifluoroacetamide was completed at a temperature of 80 degrees C after 30 min, and the detection limit of GLYP was 10 pg using m/z 454 and that of AMPA was 1 pg using m/z 396. The full mass spectra of 100 pg GLYP and of 10 pg AMPA were obtained easily. In extractions for which the Isolute HAX cartridge was employed, the mean recovery rate of GLYP and AMPA added to serum to yield concentrations of 10-0.1 microg/mL (n = 5) was 91.6 +/- 10.6% (or better), whereas that of GLYP and AMPA added to urine to yield concentrations of 100-1.0 microg/mL (n = 10) was 93.3 +/- 6.6% (or better), both of which were good rates. Also, using this method of analysis, the presence of GLYP was identified in the full mass spectra obtained from the serum of a patient who may or may not have ingested Roundup. PMID:12731658

  1. 78 FR 35265 - Notice of Receipt of Requests To Voluntarily Cancel Certain Pesticide Registrations

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-12

    ... interest to a wide range of stakeholders including environmental, human health, and agricultural advocates... name 000264-00668 Liberty ATZ Herbicide.. Atrazine, Glufosinate. 000264-00784 Renounce 20WP Cyfluthrin... Prentox Larva-Lur Propoxur. Contains Propoxur. 009779-00262 MCPA Amine Herbicide... MCPA,...

  2. Scythe (57% pelargonic acid) broadcast application for broadleaf weed control in spring-transplanted onions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Although previous studies yielded important information concerning use of pelargonic acid as a potential organic herbicide, further research is indicated to increase the understanding of the relationship among application volumes, weed species, and weed maturity on herbicidal efficacy and crop injur...

  3. Degradation of chloroacetanilide herbicides and bacterial community composition in lab-scale wetlands.

    PubMed

    Elsayed, Omniea Fawzy; Maillard, Elodie; Vuilleumier, Stéphane; Millet, Maurice; Imfeld, Gwenaël

    2015-07-01

    Degradation of chloroacetanilide herbicides rac-metolachlor, acetochlor, and alachlor, as well as associated bacterial populations, were evaluated in vertical upflow wetland columns using a combination of hydrochemical and herbicide analyses, and DNA-based approaches. Mass dissipation of chloroacetanilides, continuously supplied at 1.8-1.9 μM for 112 days, mainly occurred in the rhizosphere zone under nitrate and sulphate-reducing conditions, and averaged 61±14%, 52±12% and 29±19% for acetochlor, alachlor and rac-metolachlor, respectively. Metolachlor enantiomer fractions of 0.494±0.009 in the oxic zone and 0.480±0.005 in the rhizosphere zone indicated preferential biodegradation of the S-enantiomer. Chloroacetanilide ethane sulfonic acid and oxanilic acid degradates were detected at low concentrations only (0.5 nM), suggesting extensive degradation and the operation of yet unknown pathways for chloroacetanilide degradation. Hydrochemical parameters and oxygen concentration were major drivers of bacterial composition, whereas exposure to chloroacetanilides had no detectable impact. Taken together, the results underline the importance of anaerobic degradation of chloroacetanilides in wetlands, and highlight the potential of complementary chemical and biological approaches to characterise processes involved in the environmental dissipation of chloroacetanilides. PMID:25817759

  4. Metabolism-Based Herbicide Resistance and Cross-Resistance in Crop Weeds: A Threat to Herbicide Sustainability and Global Crop Production1

    PubMed Central

    Yu, Qin; Powles, Stephen

    2014-01-01

    Weedy plant species that have evolved resistance to herbicides due to enhanced metabolic capacity to detoxify herbicides (metabolic resistance) are a major issue. Metabolic herbicide resistance in weedy plant species first became evident in the 1980s in Australia (in Lolium rigidum) and the United Kingdom (in Alopecurus myosuroides) and is now increasingly recognized in several crop-weed species as a looming threat to herbicide sustainability and thus world crop production. Metabolic resistance often confers resistance to herbicides of different chemical groups and sites of action and can extend to new herbicide(s). Cytochrome P450 monooxygenase, glycosyl transferase, and glutathione S-transferase are often implicated in herbicide metabolic resistance. However, precise biochemical and molecular genetic elucidation of metabolic resistance had been stalled until recently. Complex cytochrome P450 superfamilies, high genetic diversity in metabolic resistant weedy plant species (especially cross-pollinated species), and the complexity of genetic control of metabolic resistance have all been barriers to advances in understanding metabolic herbicide resistance. However, next-generation sequencing technologies and transcriptome-wide gene expression profiling are now revealing the genes endowing metabolic herbicide resistance in plants. This Update presents an historical review to current understanding of metabolic herbicide resistance evolution in weedy plant species. PMID:25106819

  5. Balance between herbicidal activity and toxicity effect: a case study of the joint effects of triazine and phenylurea herbicides on Selenastrum capricornutum and Photobacterium phosphoreum.

    PubMed

    Ge, Hongming; Lin, Zhifen; Yao, Zhifeng; Gao, Ya; Cong, Yongping; Yu, Hongxia

    2014-05-01

    The use of herbicide mixtures has become a cost-effective strategy against the evolution of herbicide resistance to protect global food production. Much research has focused on investigating either the herbicidal activities or the toxicity effects of herbicides; however, few of them have investigated both factors. This study investigates the balance between herbicidal activity for Selenastrum capricornutum and toxicity effect toward Photobacterium phosphoreum by determining the joint effects of triazine (simetryn, atrazine, prometon and prometryn) and phenylurea (fenuron, monuron, monolinuron and diuron) herbicides. The results showed that among the four triazines, only simetryn exhibited a unique effect (formation of a pi-sigma bond with the D1 microalga protein and an H-bond with the Luc photobacterial protein); and among 16 triazine-phenylurea binary mixtures, only the mixtures containing simetryn resulted in TU1 values (herbicidal activities of mixtures on S. capricornutum) >TU2 values (toxicity effects of mixtures on P. phosphoreum). However, the other 12 mixtures, which did not contain simetryn, showed the opposite result (TU1herbicide mixtures was proposed. Meanwhile, some suggestions are provided firstly for herbicide combinations based on the balance between herbicidal activity and toxicity effect, which will encourage thoughtful efforts for how to best combine herbicides in a sustainable way. PMID:24681700

  6. Isolation from Agricultural Soil and Characterization of a Sphingomonas sp. Able To Mineralize the Phenylurea Herbicide Isoproturon

    PubMed Central

    Sørensen, Sebastian R.; Ronen, Zeev; Aamand, Jens

    2001-01-01

    A soil bacterium (designated strain SRS2) able to metabolize the phenylurea herbicide isoproturon, 3-(4-isopropylphenyl)-1,1-dimethylurea (IPU), was isolated from a previously IPU-treated agricultural soil. Based on a partial analysis of the 16S rRNA gene and the cellular fatty acids, the strain was identified as a Sphingomonas sp. within the α-subdivision of the proteobacteria. Strain SRS2 was able to mineralize IPU when provided as a source of carbon, nitrogen, and energy. Supplementing the medium with a mixture of amino acids considerably enhanced IPU mineralization. Mineralization of IPU was accompanied by transient accumulation of the metabolites 3-(4-isopropylphenyl)-1-methylurea, 3-(4-isopropylphenyl)-urea, and 4-isopropyl-aniline identified by high-performance liquid chromatography analysis, thus indicating a metabolic pathway initiated by two successive N-demethylations, followed by cleavage of the urea side chain and finally by mineralization of the phenyl structure. Strain SRS2 also transformed the dimethylurea-substituted herbicides diuron and chlorotoluron, giving rise to as-yet-unidentified products. In addition, no degradation of the methoxy-methylurea-substituted herbicide linuron was observed. This report is the first characterization of a pure bacterial culture able to mineralize IPU. PMID:11722885

  7. Broad 4-Hydroxyphenylpyruvate Dioxygenase Inhibitor Herbicide Tolerance in Soybean with an Optimized Enzyme and Expression Cassette[W][OPEN

    PubMed Central

    Siehl, Daniel L.; Tao, Yumin; Albert, Henrik; Dong, Yuxia; Heckert, Matthew; Madrigal, Alfredo; Lincoln-Cabatu, Brishette; Lu, Jian; Fenwick, Tamara; Bermudez, Ericka; Sandoval, Marian; Horn, Caroline; Green, Jerry M.; Hale, Theresa; Pagano, Peggy; Clark, Jenna; Udranszky, Ingrid A.; Rizzo, Nancy; Bourett, Timothy; Howard, Richard J.; Johnson, David H.; Vogt, Mark; Akinsola, Goke; Castle, Linda A.

    2014-01-01

    With an optimized expression cassette consisting of the soybean (Glycine max) native promoter modified for enhanced expression driving a chimeric gene coding for the soybean native amino-terminal 86 amino acids fused to an insensitive shuffled variant of maize (Zea mays) 4-hydroxyphenylpyruvate dioxygenase (HPPD), we achieved field tolerance in transgenic soybean plants to the HPPD-inhibiting herbicides mesotrione, isoxaflutole, and tembotrione. Directed evolution of maize HPPD was accomplished by progressively incorporating amino acids from naturally occurring diversity and novel substitutions identified by saturation mutagenesis, combined at random through shuffling. Localization of heterologously expressed HPPD mimicked that of the native enzyme, which was shown to be dually targeted to chloroplasts and the cytosol. Analysis of the native soybean HPPD gene revealed two transcription start sites, leading to transcripts encoding two HPPD polypeptides. The N-terminal region of the longer encoded peptide directs proteins to the chloroplast, while the short form remains in the cytosol. In contrast, maize HPPD was found almost exclusively in chloroplasts. Evolved HPPD enzymes showed insensitivity to five inhibitor herbicides. In 2013 field trials, transgenic soybean events made with optimized promoter and HPPD variant expression cassettes were tested with three herbicides and showed tolerance to four times the labeled rates of mesotrione and isoxaflutole and two times the labeled rates of tembotrione. PMID:25192697

  8. Finding minimal herbicide concentrations in ground water? Try looking for their degradates

    USGS Publications Warehouse

    Kolpin, D.W.; Thurman, E.M.; Linhart, S.M.

    2000-01-01

    Extensive research has been conducted regarding the occurrence of herbicides in the hydrologic system, their fate, and their effects on human health and the environment. Few studies, however, have considered herbicide transformation products (degradates). In this study of Iowa ground water, herbicide degradates were frequently detected. In fact, herbicide degradates were eight of the 10 most frequently detected compounds. Furthermore, a majority of a herbicide's measured concentration was in the form of its degradates — ranging from 55 to over 99%. The herbicide detection frequencies and concentrations varied significantly among the major aquifer types sampled. These differences, however, were much more pronounced when herbicide degradates were included. Aquifer types presumed to have the most rapid recharge rates (alluvial and bedrock/karst region aquifers) were those most likely to contain detectable concentrations of herbicide compounds. Two indirect estimates of ground-water age (depth of well completion and dissolved-oxygen concentration) were used to separate the sampled wells into general vulnerability classes (low, intermediate, and high). The results show that the herbicide detection frequencies and concentrations varied significantly among the vulnerability classes regardless of whether or not herbicide degradates were considered. Nevertheless, when herbicide degradates were included, the frequency of herbicide compound detection within the highest vulnerability class approached 90%, and the median total herbicide residue concentration increased over an order of magnitude, relative to the parent compounds alone, to 2 μg/l. The results from this study demonstrate that obtaining data on herbicide degradates is critical for understanding the fate of herbicides in the hydrologic system. Furthermore, the prevalence of herbicide degradates documented in this study suggests that to accurately determine the overall effect on human health and the environment of

  9. Degradates provide insight to spatial and temporal trends of herbicides in ground water

    USGS Publications Warehouse

    Kolpin, D.W.; Schnoebelen, D.J.; Thurman, E.M.

    2004-01-01

    During 2001, 86 municipal wells in Iowa were sampled and analyzed for 21 herbicide parent compounds and 24 herbicide degradates. The frequency of detection increased from 17% when only herbicide parent compounds were considered to 53% when both herbicide parents and degradates were considered. Thus, the transport of herbicide compounds to ground water is substantially underestimated when herbicide degradates are not considered. A significant difference in the results among the major aquifer types was apparent only when both herbicide parent compounds and their degradates were considered. In addition, including herbicide degradates greatly improved the statistical relation to the age of the water being sampled. When herbicide parent compounds are considered, only 40% of the wells lacking a herbicide detection could be explained by the age of the water predating herbicide use. However, when herbicide degradates were also considered, 80% of the ground water samples lacking a detection could be explained by the age of the water predating herbicide use. Finally, a temporal pattern in alachlor concentrations in ground water could only be identified when alachlor degradates were considered.

  10. Herbicides and transformation products in surface waters of the Midwestern United States

    USGS Publications Warehouse

    Battaglin, W.A.; Thurman, E.M.; Kalkhoff, S.J.; Porter, S.D.

    2003-01-01

    Most herbicides applied to crops are adsorbed by plants or transformed (degraded) in the soil, but small fractions are lost from fields and either move to streams in overland runoff, near surface flow, or subsurface drains, or they infiltrate slowly to ground water. Herbicide transformation products (TPs) can be more or less mobile and more or less toxic in the environment than their source herbicides. To obtain information on the concentrations of selected herbicides and TPs in surface waters of the Midwestern United States, 151 water samples were collected from 71 streams and five reservoir outflows in 1998. These samples were analyzed for 13 herbicides and 10 herbicide TPs. Herbicide TPs were found to occur as frequently or more frequently than source herbicides and at concentrations that were often larger than their source herbicides. Most samples contained a mixture of more than 10 different herbicides or TPs. The ratios of TPs to herbicide concentrations can be used to determine the source of herbicides in streams. Results of a two-component mixing model suggest that on average 90 percent or more of the herbicide mass in Midwestern streams during early summer runoff events originates from the runoff and 10 percent or less comes from increased ground water discharge.

  11. Influence of herbicide-resistant canola on the environmental impact of weed management.

    PubMed

    Brimner, Theresa A; Gallivan, Gordon James; Stephenson, Gerald R

    2005-01-01

    The growth of herbicide-resistant canola varieties increased from 10% of the canola area in Canada in 1996, when the technology was first introduced, to 80% in 2000. From 1995 to 2000, the amount of herbicide active ingredient applied per hectare of canola declined by 42.8% and the Environmental Impact (EI) per hectare, calculated using the Environmental Impact Quotient for individual herbicides and the amounts of active ingredients applied, declined 36.8%. The amount of herbicide active ingredient per hectare applied to conventional canola was consistently higher than that applied to herbicide-resistant canola each year between 1996 and 2000. Similarly, the EI of herbicide use per hectare in conventional canola was higher than that of herbicide-resistant canola during the same time period. Since 1996, herbicide use has shifted from broadcast applications of soil-active herbicides to post-emergence applications of herbicides with broad-spectrum foliar activity. The decline in herbicide use and EI since the introduction of herbicide-resistant varieties was due to increased use of chemicals with lower application rates, a reduced number of applications and a decreased need for herbicide combinations. PMID:15593073

  12. Herbicide Phosphinothricin Causes Direct Stimulation Hormesis

    PubMed Central

    Dragićević, Milan; Platiša, Jelena; Nikolić, Radomirka; Todorović, Slađana; Bogdanović, Milica; Mitić, Nevena; Simonović, Ana

    2013-01-01

    Herbicide phosphinothricin (PPT) inhibits glutamine synthetase (GS), a key enzyme in nitrogen assimilation, thus causing ammonia accumulation, glutamine depletion and eventually plant death. However, the growth response of Lotus corniculatus L. plants immersed in solutions with a broad range of PPT concentrations is biphasic, with pronounced stimulating effect on biomass production at concentrations ≤ 50 μM and growth inhibition at higher concentrations. The growth stimulation at low PPT concentrations is a result of activation of chloroplastic isoform GS2, while the growth suppression is caused by inhibition of both cytosolic GS1 and GS2 at higher PPT concentrations. Since the results are obtained in cell-free system (e.g. protein extracts), to which the principles of homeostasis are not applicable, this PPT effect is an unambiguous example of direct stimulation hormesis. A detailed molecular mechanism of concentration-dependent interaction of both PPT and a related GS inhibitor, methionine sulfoximine, with GS holoenzymes is proposed. The mechanism is in concurrence with all experimental and literature data. PMID:23983663

  13. Microorganisms capable of metabolizing the herbicide metolachlor.

    PubMed Central

    Saxena, A; Zhang, R W; Bollag, J M

    1987-01-01

    We screened several strains of microorganisms and microbial populations for their ability to mineralize or transform the herbicide metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)-acetami de] because such cultures would potentially be useful in the cleanup of contaminated sites. Although we used various inocula and enrichment culture techniques, we were not able to isolate microorganisms that could mineralize metolachlor. However, strains of Bacillus circulans, Bacillus megaterium, Fusarium sp., Mucor racemosus, and an actinomycete were found to transform metolachlor. Several metabolites could be determined with high-performance liquid chromatography. The tolerance of the strains to high concentrations of metolachlor was also evaluated for the usefulness of the strains for decontamination. Tolerance of the actinomycete to metolachlor concentrations over 200 ppm (200 micrograms/ml) was low and could not be increased by doubling the sucrose concentration in the growth medium or by using a large biomass as inoculum. However, a Fusarium sp. could grow and transform metolachlor up to a concentration of 300 ppm. PMID:3105457

  14. Pedobacter nanyangensis sp. nov., isolated from herbicide-contaminated soil.

    PubMed

    Zhang, Hao; Zhang, Jing; Song, Man; Cheng, Ming-gen; Wu, Ya-dong; Guo, Su-hui; Li, Qiang; Hong, Qing; Huang, Xing

    2015-10-01

    A Gram-stain-negative, strictly aerobic, non-spore-forming, motile, rod-shaped bacterium, designated Q-4T, was isolated from a herbicide-contaminated soil sample in Nanyang, Henan province, China. Strain Q-4T grew optimally in the LB medium without NaCl supplement at a pH range of 6.0–7.0 and a temperature of 30 °C. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain Q-4T was most closely related to ‘Pedobacter zeaxanthinifaciens’ TDMA-5 (97.4 % 16S rRNA gene sequence similarity), followed by Pedobacter xixiisoli S27T (95.8 %). The genomic DNA G+C content of strain Q-4T was 41.8 mol%. MK-7 was the major respiratory quinone. Phosphatidylethanolamine and phosphoaminolipid were the major polar lipids. The major fatty acids were iso-C15 : 0, iso-C17 : 0 3-OH, C16 : 1ω6c and/or C16 : 1ω7c (summed feature 3) and C16 : 1ω7c/C16 : 1ω6c (summed feature 3). Strain Q-4T showed low DNA–DNA relatedness with ‘P. zeaxanthinifaciens’ TDMA-5 (21.4 ± 0.6 %). Physiological and biochemical characteristics are able to distinguish strain Q-4T from the most closely related species of the genus Pedobacter. On the basis of genotypic and phenotypic data, strain Q-4T is considered to represent a novel species of the genus Pedobacter, for which the name Pedobacter nanyangensis sp. nov. is proposed. The type strain is Q-4T ( = KCTC 42442T = ACCC 19798T). PMID:26297219

  15. Reducing the risks of herbicide resistance: best management practices and recommendations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Herbicides are the foundation of weed control in commercial crop production. However, herbicide-resistant weed populations are developing rapidly in response to selection pressure. Critical practices include reducing selection through diversification of weed control techniques, minimizing spread of ...

  16. Bioactivity of Several Herbicides on the Nanogram Level Under Different Soil Moisture Conditions.

    PubMed

    Jung, S C; Kuk, Y I; Senseman, S A; Ahn, H G; Seong, C N; Lee, D J

    2015-01-01

    In this study, a double-tube centrifuge method was employed to determine the effects of soil moisture on the bioactivity of cafenstrole, pretilachlor, benfuresate, oxyfluorfen and simetryn. In general, the available herbicide concentration in soil solution (ACSS) showed little change as soil moisture increased for herbicides. The total available herbicide in soil solution (TASS) typically increased as soil moisture increased for all herbicides. The relationship between TASS and % growth rate based on dry weight showed strong linear relationships for both cafenstrole and pretilachlor, with r2 values of 0.95 and 0.84, respectively. Increasing TASS values were consistent with increasing herbicide water solubility, with the exception of the ionizable herbicide simetryn. Plant absorption and % growth rate exhibited a strong linear relationship with TASS. According to the results suggested that TASS was a better predictor of herbicidal bioactivity than ACSS for all herbicides under unsaturated soil moisture conditions. PMID:26328425

  17. ASSESSING THE RISKS OF NON-TARGET TERRESTRIAL PLANTS FROM HERBICIDES

    EPA Science Inventory

    Use of chemical herbicides to reduce weed competition is a major contributing factor to the high productivity of conventional intensive agricultural cropping systems. However, because of their inherent phytotoxicity, movement of herbicides from target crops and soils can adverse...

  18. Redstem filaree control in sugarbeets with micro-rate herbicide treatments

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Field experiments were conducted at the University of Wyoming Powell Research and Extension Center to evaluate redstem filaree control and sugarbeet response to several herbicide treatments. Preplant herbicides used were ethofumesate and pyrazon applied alone or in combination. Postemergence herbici...

  19. HERBICIDE AND NITRATE IN SURFACE AND GROUNDWATER: RESULTS FROM THE IOWA MSEA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Iowa Management System Evaluation Area (MSEA) program sponsored multidisciplinary research at plot, field and watershed scales. Water monitoring studies targeting herbicide and nitrate transport were conducted in different hydrogeologic settings. In central and northeast Iowa, herbicides were tr...

  20. Triazolopyrimidines as a New Herbicidal Lead for Combating Weed Resistance Associated with Acetohydroxyacid Synthase Mutation.

    PubMed

    Liu, Yu-Chao; Qu, Ren-Yu; Chen, Qiong; Yang, Jing-Fang; Cong-Wei, Niu; Zhen, Xi; Yang, Guang-Fu

    2016-06-22

    Acetohydroxyacid synthase (AHAS; also known as acetolactate synthase; EC 2.2.1.6, formerly EC 4.1.3.18) is the first common enzyme in the biosynthetic pathway leading to the branched-chain amino acids in plants and a wide range of microorganisms. Weed resistance to AHAS-inhibiting herbicides, increasing at an exponential rate, is becoming a global problem and leading to an urgent demand of developing novel compounds against both resistant and wild AHAS. In the present work, a series of novel 2-aroxyl-1,2,4-triazolopyrimidine derivatives (a total of 55) were designed and synthesized with the aim to discover an antiresistant lead compound. Fortunately, the screening results indicated that many of the newly synthesized compounds showed a better, even excellent, inhibition effect against both the wild-type Arabidopsis thaliana AHAS and P197L mutants. Among them, compounds 5-3 to 5-17, compounds 5-19 to 5-26, compounds 5-28 to 5-45, and compound 5-48 have the lower values of resistance factor (RF) and display a potential power to overcome resistance associated with the P197L mutation in the enzyme levels. Further greenhouse in vivo assay showed that compounds 5-15 and 5-20 displayed "moderate" to "good" herbicidal activity against both the wild type-and the resistant (P197L mutation) Descurainia sophia, even at a rate as low as 0.9375 (g of ai/ha). The above results indicated that these two compounds could be used as new leads for the future development of antiresistance herbicides. PMID:27265721

  1. Catchment-scale herbicides transport: Theory and application

    NASA Astrophysics Data System (ADS)

    Bertuzzo, E.; Thomet, M.; Botter, G.; Rinaldo, A.

    2013-02-01

    This paper proposes and tests a model which couples the description of hydrologic flow and transport of herbicides at catchment scales. The model accounts for streamflow components' age to characterize short and long term fluctuations of herbicide flux concentrations in stream waters, whose peaks exceeding a toxic threshold are key to exposure risk of aquatic ecosystems. The model is based on a travel time formulation of transport embedding a source zone that describes near surface herbicide dynamics. To this aim we generalize a recently proposed scheme for the analytical derivation of travel time distributions to the case of solutes that can be partially taken up by transpiration and undergo chemical degradation. The framework developed is evaluated by comparing modeled hydrographs and atrazine chemographs with those measured in the Aabach agricultural catchment (Switzerland). The model proves reliable in defining complex transport features shaped by the interplay of long term processes, related to the persistence of solute components in soils, and short term dynamics related to storm inter-arrivals. The effects of stochasticity in rainfall patterns and application dates on concentrations and loads in runoff are assessed via Monte Carlo simulations, highlighting the crucial role played by the first rainfall event occurring after herbicide application. A probabilistic framework for critical determinants of exposure risk to aquatic communities is defined. Modeling of herbicides circulation at catchment scale thus emerges as essential tools for ecological risk assessment.

  2. Effects of the herbicide imazapyr on juvenile Oregon spotted frogs

    USGS Publications Warehouse

    Yahnke, Amy E.; Grue, Christian E.; Hayes, Marc P.; Troiano, Alexandra T.

    2013-01-01

    Conflict between native amphibians and aquatic weed management in the Pacific Northwest is rarely recognized because most native stillwater-breeding amphibian species move upland during summer, when herbicide application to control weeds in aquatic habitats typically occurs. However, aquatic weed management may pose a risk for aquatic species present in wetlands through the summer, such as the Oregon spotted frog (OSF, Rana pretiosa), a state endangered species in Washington. Acute toxicity of herbicides used to control aquatic weeds tends to be low, but the direct effects of herbicide tank mixes on OSFs have remained unexamined. We exposed juvenile OSFs to tank mixes of the herbicide imazapyr, a surfactant, and a marker dye in a 96-h static-renewal test. The tank mix was chosen because of its low toxicity to fish and its effectiveness in aquatic weed control. Concentrations were those associated with low-volume (3.5 L/ha) and high-volume (7.0 L/ha) applications of imazapyr and a clean-water control. Following exposure, frogs were reared for two months in clean water to identify potential latent effects on growth. Endpoints evaluated included feeding behavior, growth, and body and liver condition indices. We recorded no mortalities and found no significant differences for any end point between the herbicide-exposed and clean-water control frogs. The results suggest that imazapyr use in wetland restoration poses a low risk of direct toxic effects on juvenile OSFs.

  3. Phenylurea herbicide sorption to biochars and agricultural soil

    PubMed Central

    WANG, DAOYUAN; MUKOME, FUNGAI N. D.; YAN, DENGHUA; WANG, HAO; SCOW, KATE M.; PARIKH, SANJAI J.

    2016-01-01

    Biochar is increasingly been used as a soil amendment to improve water holding capacity, reduce nutrient leaching, increase soil pH and also as a means to reduce contamination through sorption of heavy metals or organic pollutants. The sorption behavior of three phenylurea herbicides (monuron, diuron, linuron) on five biochars (Enhanced Biochar, Hog Waste, Turkey Litter, Walnut Shell and Wood Feedstock) and an agricultural soil (Yolo silt loam) was investigated using a batch equilibration method. Sorption isotherms of herbicides to biochars were well described by the Freundlich model (R2 = 0.93 -- 0.97). The adsorption KF values ranged from 6.94 to 1306.95 mg kg−1 and indicated the sorption of herbicides in the biochars and Yolo soil was in the sequence of linuron > diuron > monuron and walnut shell biochar > wood feedstock biochar > turkey litter biochar > enhanced biochar > hog waste biochar > Yolo soil. These data show that sorption of herbicides to biochar can have both positive (reduced off-site transport) and negative (reduced herbicide efficacy) implications and specific biochar properties, such as H/C ratio and surface area, should be considered together with soil type, agriculture chemical and climate condition in biochar application to agricultural soil to optimize the system for both agricultural and environmental benefits. PMID:26065514

  4. EEI pulls out of herbicide fight: utilities plan alliance

    SciTech Connect

    Utroska, D.

    1980-07-01

    The Edison Electric Institute has decided it will not go into battle against the Environmental Protection Agency over the agency's suspension and possible cancellation of the herbicide 2,4,5-T. The herbicide is used extensively by electric utilities for woody brush control along transmission and distribution rights-of-way. Edison Electric Institute determined that the cost to participate in the hearing was not in line with the total amount of information the company could offer. Although Dow Chemical Co., the principal manufacturer of the chemical, still plans to testify at the hearing on benefits, several utility companies are attempting to organize a consortium of interested utilities to testify instead of the manufacturer. The Environmental Protection Agency's recent questioning of another herbicide, 2,4-D, has prompted greater interest in 2,4,5-T support. The chemical 2,4-D constitutes the base for many of the most important alternate herbicides. With both 2,4-D and 2,4,5-T banned, many feel the herbicide industry would collapse. Interest in 2,4,5-T began in 1976 when a causal relationship between spontaneous abortions and forest spraying with dioxin was suggested by eight women living in Alsea, Oregon. (SAC)

  5. Cloud based, Open Source Software Application for Mitigating Herbicide Drift

    NASA Astrophysics Data System (ADS)

    Saraswat, D.; Scott, B.

    2014-12-01

    The spread of herbicide resistant weeds has resulted in the need for clearly marked fields. In response to this need, the University of Arkansas Cooperative Extension Service launched a program named Flag the Technology in 2011. This program uses color-coded flags as a visual alert of the herbicide trait technology within a farm field. The flag based program also serves to help avoid herbicide misapplication and prevent herbicide drift damage between fields with differing crop technologies. This program has been endorsed by Southern Weed Science Society of America and is attracting interest from across the USA, Canada, and Australia. However, flags have risk of misplacement or disappearance due to mischief or severe windstorms/thunderstorms, respectively. This presentation will discuss the design and development of a cloud-based, free application utilizing open-source technologies, called Flag the Technology Cloud (FTTCloud), for allowing agricultural stakeholders to color code their farm fields for indicating herbicide resistant technologies. The developed software utilizes modern web development practices, widely used design technologies, and basic geographic information system (GIS) based interactive interfaces for representing, color-coding, searching, and visualizing fields. This program has also been made compatible for a wider usability on different size devices- smartphones, tablets, desktops and laptops.

  6. The structure-activity relationship in herbicidal monosubstituted sulfonylureas

    SciTech Connect

    Li, Zheng-Ming; Ma, Yi; Guddat, Luke; Cheng, Pei-Quan; Wang, Jian-Guo; Pang, Siew S; Dong, Yu-Hui; Lai, Cheng-Ming; Wang, Ling-Xiu; Jia, Guo-Feng; Li, Yong-Hong; Wang, Su-Hua; Liu, Jie; Zhao, Wei-Guang; Wang, Bao-Lei

    2012-05-24

    The herbicide sulfonylurea (SU) belongs to one of the most important class of herbicides worldwide. It is well known for its ecofriendly, extreme low toxicity towards mammals and ultralow dosage application. The original inventor, G Levitt, set out structure-activity relationship (SAR) guidelines for SU structural design to attain superhigh bioactivity. A new approach to SU molecular design has been developed. After the analysis of scores of SU products by X-ray diffraction methodology and after greenhouse herbicidal screening of 900 novel SU structures synthesized in the authors laboratory, it was found that several SU structures containing a monosubstituted pyrimidine moiety retain excellent herbicidal characteristics, which has led to partial revision of the Levitt guidelines. Among the novel SU molecules, monosulfuron and monosulfuron-ester have been developed into two new herbicides that have been officially approved for field application and applied in millet and wheat fields in China. A systematic structural study of the new substrate-target complex and the relative mode of action in comparison with conventional SU has been carried out. A new mode of action has been postulated.

  7. Syntheses and herbicidal activities of novel triazolinone derivatives.

    PubMed

    Luo, Yan-Ping; Jiang, Li-Li; Wang, Guo-Dong; Chen, Qiong; Yang, Guang-Fu

    2008-03-26

    Protoporphyrinogen oxidase (Protox, EC 1.3.3.4) has been identified as one of the most important action targets of herbicides. To search for novel Protox inhibitors, a series of title compounds 1, 2, and 3 were designed and synthesized by introducing three types of pharmacophores, cyclic imide, phenylurea, and ( E)-methyl 2-methoxyimino-2- o-tolylacetate, into the scaffold of triazolinone. The bioassay results indicated that the resulting cyclic imide-type triazolinones 1 displayed much better herbicidal activities than phenylurea-type triazolinones 2. Most fortunately, compound 3, methyl 2-[3-methyl-(2-fluoro-4-chloro-5-ethylsulfonamidephenyl)-4,5-dihydro-5-oxo-1 H-1,2,4-triazol-4-yl]methylenephenyl-2-( E)-methoxyiminoacetate, was found to be the most promising candidate due to its comparable herbicidal activity at 75-150 g of active ingredient/ha with the commercial product sulfentrazone. On the basis of test results of herbicidal spectrum and crop selectivity, compound 3 could be developed as a postemergent herbicide used for the control of broadleaf weeds in rice fields. PMID:18298068

  8. Changes in concentrations of triazine and acetamide herbicides by bank filtration, ozonation, and chlorination in a public water supply

    USGS Publications Warehouse

    Verstraeten, Ingrid M.; Thurman, E.M.; Lindsey, M.E.; Lee, E.C.; Smith, R.D.

    2002-01-01

    The changes in triazine and acetamide concentrations in water during natural and artificial treatment by bank filtration, ozonation, filtration, and chlorination were measured at the well field and drinking water treatment plant of Lincoln, Nebraska, USA. The city's groundwater supply is affected by induced infiltration and transport of triazines and acetamide herbicides from the Platte River in late spring and early summer. The objective of the study was to evaluate the effect of infiltration and treatment on the presence of triazines and acetamides in drinking water. Samples of river water, well water, and public supply water at various stages of water treatment were collected from 1997-1999 during spring-runoff when the presence of herbicides in the Platte River is largest. In 1999, parent compounds were reduced by 76% of the concentration present in river water (33% by bank filtration, 41% by ozonation, and 1.5% by chlorination). Metabolites of herbicides for which analytical techniques existed were reduced by 21% (plus 26% by bank filtration, minus 23% by ozonation, and minus 24% by chlorination). However, increases in concentrations of specific metabolite compounds were identified after bank filtration and ozonation. After bank filtration, increases in cyanazine amide, cyanazine acid, and deethylcyanazine acid were identified. After ozonation, concentrations of deisopropylatrazine, deethylatrazine, didealkylatrazine, atrazine amide-I, hydroxydeethylatrazine, hydroxydeisopopylatrazine, deethylcyanazine acid, and deethylcyanazine increased. Concentrations of cyanazine acid and ethanesulfonic and oxanilic acids of acetamides decreased during ozonation. Our findings suggest that bank filtration and ozonation of water in part can shift the assessment of risk to human health associated with the consumption of the water from the parent compounds to their degradation products.

  9. Development of a method based on accelerated solvent extraction and liquid chromatography/mass spectrometry for determination of arylphenoxypropionic herbicides in soil.

    PubMed

    Marchese, S; Perret, D; Gentili, A; Curini, R; Marino, A

    2001-01-01

    A sensitive and specific analytical procedure for determining arylphenoxypropionic herbicides in soil samples, using Ionspray ionization (ISI) liquid chromatography/mass spectrometry (LC/MS), is presented. Arylphenoxypropionic acids are a new class of herbicides used for selective removal of most grass species from any non-grass crop, commercialized as herbicide esters. Previous studies have shown that the esters undergo fast hydrolysis in the presence of vegetable tissues and soil bacteria, yelding the corresponding free acid. The feasibility of rapidly extracting arylphenoxypropionic herbicides from soil by accelerated solvent extraction (ASE) techniques was evaluated. Four different soil samples were fortified with target compounds at levels of 5 and 20 ng/g by following a procedure able to mimic weathered soils. Herbicides were extracted by a methanol/water (80:20 v/v) solution (0.12 M) of NaCl at 90 degrees C. After clean-up using graphitized carbon black (GCB) as absorbent, the extract was analyzed by HPLC/ISI-MS. The effect of concentration of acid in the mobile phase on the response of ISI-MS was investigated. The effects of varying the orifice plate voltage on the production of diagnostic fragment ions, and on the response of the MS detector, were also investigated. The ISI-MS response was linearly related to the amounts of analytes injected between 1 and 200 ng. The limit of detection (signal-to-noise ratio = 3) of the method for the pesticides in soil samples was estimated to be less than 1 ng/g. PMID:11291116

  10. 77 FR 76170 - Presumption of Exposure to Herbicides for Blue Water Navy Vietnam Veterans Not Supported

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-26

    ... accept and review all Blue Water Navy Vietnam Veteran claims based on herbicide exposure on a case-by... widely used herbicide was Agent Orange. Agent Orange was contaminated with the highly toxic chemical 2, 3..., 105 Stat. 11, established a presumption of herbicide exposure for veterans who had served in...

  11. Herbicide-Resistance in Crops and Weeds: A Historical and Current Perspective

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Herbicides are the principal economic means of weed management on >90% of U.S. farmland. Herbicide-resistant crop cultivars have been used widely since 1995. Pest disciplines and other life sciences have various definitions of resistance that share commonalities. Development of herbicide resistant w...

  12. Agricultural herbicide transport in a first-order intermittent stream, Nebraska, USA

    USGS Publications Warehouse

    Vogel, J.R.; Linard, J.I.

    2011-01-01

    The behavior of herbicides in surface waters is a function of many variables, including scale of the watershed, physical and chemical properties of the herbicide, physical and chemical properties of the soil, rainfall intensity, and time of year. In this study, the transport of 6 herbicides and 12 herbicide degradates was examined during the 2004 growing season in an intermediate-scale agricultural watershed (146 ha) that is drained by a first-order intermittent stream, and the mass load for each herbicide in the stream was estimated. The herbicide load during the first week of storm events after application ranged from 17% of annual load for trifluralin to 84% of annual load for acetochlor. The maximum weekly herbicide load in the stream was generally within the first 3 weeks after application for those compounds that were applied within the watershed during 2004, and later for herbicides not applied within the watershed during 2004 but still detected in the stream. The apparent dominant mode of herbicide transport in the stream-determined by analysis amongst herbicide and conservative ion concentrations at different points in the hydrograph and in base flow samples-was either overland runoff or shallow subsurface flow, depending on the elapsed time after application and type of herbicide. The load as a percentage of use (LAPU) for the parent compounds in this study was similar to literature values for those compounds applied by the farmer within the watershed, but smaller for those herbicides that had rainfall as their only source within the watershed.

  13. Dissipation and Movement of Soil-applied Herbicide Combinations in Corn, Dry Bean and Sunflower

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pre-emergent herbicides are used to control weeds in most of our crops. Combinations of herbicides are applied to broaden the spectrum of weeds controlled. Although many studies have been done on the behavior of individual herbicides in the soil, there are few studies that examine the fate of mult...

  14. Transcript markers of herbicide stress in Arabidopsis and their cross-species extrapolation to Brassica

    EPA Science Inventory

    Low concentrations and short environmental persistence times of some herbicides make it difficult to develop analytical methods to detect herbicide residues in plants or soils. In contrast, genomics may provide tools to identify herbicide exposure to plants in field settings. Usi...

  15. Why have no new herbicide modes of action appeared in recent years?

    PubMed

    Duke, Stephen O

    2012-04-01

    Herbicides with new modes of action are badly needed to manage the evolution of resistance of weeds to existing herbicides. Yet no major new mode of action has been introduced to the market place for about 20 years. There are probably several reasons for this. New potential products may have remained dormant owing to concerns that glyphosate-resistant (GR) crops have reduced the market for a new herbicide. The capture of a large fraction of the herbicide market by glyphosate with GR crops led to significantly diminished herbicide discovery efforts. Some of the reduced herbicide discovery research was also due to company consolidations and the availability of more generic herbicides. Another problem might be that the best herbicide molecular target sites may have already been discovered. However, target sites that are not utilized, for which there are inhibitors that are highly effective at killing plants, suggests that this is not true. Results of modern methods of target site discovery (e.g. gene knockout methods) are mostly not public, but there is no evidence of good herbicides with new target sites coming from these approaches. In summary, there are several reasons for a long dry period for new herbicide target sites; however, the relative magnitude of each is unclear. The economic stimulus to the herbicide industry caused by the evolution of herbicide-resistant weeds, especially GR weeds, may result in one or more new modes of action becoming available in the not too distant future. PMID:22190296

  16. Vegetable Response to Herbicides Applied to Low-Density Polyethylene Mulch Prior to Transplant

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Few herbicides are available for weed control in vegetables. The elimination of methyl bromide increases the need for herbicides. An experiment was conducted to evaluate crop injury from herbicides applied to LDPE mulch prior to transplant. Irrigation (1 cm) or no irrigation following crop transplan...

  17. Detection of herbicides in water and their interactions with chlorella kessleri

    NASA Astrophysics Data System (ADS)

    de Vries, Thorsten; Duling, Viviane; Anders, Angelika

    1999-09-01

    For the first time the herbicides ethidimuron, amizol and methabenzthiazuron were detected in water by means of time resolved laser fluorescence spectroscopy. The suitability of the algae chlorella kessleri as a biological indicator was tested. By using time resolved LIF, the herbicides' absorption spectra and their effects on the fluorescence properties of the algae it was possible to distinguish between the three herbicides.

  18. Presumption of Herbicide Exposure and Presumption of Disability During Service for Reservists Presumed Exposed to Herbicide. Interim final rule.

    PubMed

    2015-06-19

    The Department of Veterans Affairs (VA) is amending its regulation governing individuals presumed to have been exposed to certain herbicides. Specifically, VA is expanding the regulation to include an additional group consisting of individuals who performed service in the Air Force or Air Force Reserve under circumstances in which they had regular and repeated contact with C-123 aircraft known to have been used to spray an herbicide agent ("Agent Orange'') during the Vietnam era. In addition, the regulation will establish a presumption that members of this group who later develop an Agent Orange presumptive condition were disabled during the relevant period of service, thus establishing that this service constituted "active, naval, military or air service.'' The effect of this action is to presume herbicide exposure for these individuals and to allow individuals who were exposed to herbicides during reserve service to establish veteran status for VA purposes and eligibility for some VA benefits. The need for this action results from a recent decision by the Secretary of Veterans Affairs to acknowledge that individuals who had regular and repeated exposure to C-123 aircraft that the United States Air Force used to spray the herbicides in Vietnam during Operation Ranch Hand were exposed to Agent Orange. PMID:26103644

  19. Monitoring of herbicide effect in maize based on electrical measurements

    NASA Astrophysics Data System (ADS)

    Cseresnyés, I.; Fekete, G.; Végh, K.; Székács, A.; Mörtl, M.; Rajkai, K.

    2012-07-01

    The effect of the herbicide acetochlor on root growth was studied by a non-destructive electrical impedance and capacitance method in pot experiments on maize. Acetochlor was applied both as single active ingredient and mixed with safener AD-67 in two dosages. Without safener addition, acetochlor had a permanent inhibiting effect on plant root expansion. The safener AD-67 was capable of providing protective effect against herbicide application. High correlations between root electrical impedance or capacitance and the root dry mass or surface area under our laboratory conditions were confirmed by plant harvest method. Root electrical impedance and capacitance measurements proved to be valid for monitoring the effect of the herbicide influencing root development and for distinguishing plant groups subjected to different stress conditions.

  20. Dacthal and chlorophenoxy herbicides and chlorothalonil fungicide in eggs of osprey (Pandion haliaetus) from the Duwamish-Lake Washington-Puget Sound area of Washington state, USA

    USGS Publications Warehouse

    Chu, S.; Henny, C.J.; Kaiser, J.L.; Drouillard, K.G.; Haffner, G.D.; Letcher, R.J.

    2007-01-01

    Current-use chlorophenoxy herbicides including 2,4-dichlorophenoxyacetic acid, dicamba, triclopyr, dicamba, dimethyl tetrachloroterephthalate (DCPA or dacthal), and the metabolite of pyrethroids, 3-phenoxybenzoic acid (3-PBA), and the fungicide, chlorothalonil, were investigated in the eggs of osprey (Pandion haliaetus) that were collected from 15 sites from five study areas Puget Sound/Seattle area of Washington State, USA. DCPA differs from acidic chlorophenoxy herbicides, and is not readily hydrolyzed to free acid or acid metabolites, and thus we developed a new method. Of the 12 chlorophenoxy herbicides and chlorothalonil analyzed only DCPA could be quantified at six of these sites (2.0 to 10.3 pg/g fresh weight). However, higher levels (6.9 to 85.5 pg/g fresh weight) of the unexpected DCPA structural isomer, dimethyl tetrachlorophthalate (diMe-TCP) were quantified in eggs from all sites. diMe-TCP concentrations tended to be higher in eggs from the Everett Harbor area. As diMe-TCP is not an industrial product, and not commercially available, the source of diMe-TCP is unclear. Regardless, these findings indicate that DCPA and diMe-TCP can be accumulated in the food chain of fish-eating osprey, and transferred in ovo to eggs, and thus may be of concern to the health of the developing chick and the general reproductive health of this osprey population. ?? 2006 Elsevier Ltd. All rights reserved.

  1. Dacthal and chlorophenoxy herbicides and chlorothalonil fungicide in eggs of osprey (Pandion haliaetus) from the Duwamish-Lake Washington-Puget Sound area of Washington state, USA.

    PubMed

    Chu, Shaogang; Henny, Charles J; Kaiser, James L; Drouillard, Ken G; Haffner, G Douglas; Letcher, Robert J

    2007-01-01

    Current-use chlorophenoxy herbicides including 2,4-dichlorophenoxyacetic acid, dicamba, triclopyr, dicamba, dimethyl tetrachloroterephthalate (DCPA or dacthal), and the metabolite of pyrethroids, 3-phenoxybenzoic acid (3-PBA), and the fungicide, chlorothalonil, were investigated in the eggs of osprey (Pandion haliaetus) that were collected from 15 sites from five study areas Puget Sound/Seattle area of Washington State, USA. DCPA differs from acidic chlorophenoxy herbicides, and is not readily hydrolyzed to free acid or acid metabolites, and thus we developed a new method. Of the 12 chlorophenoxy herbicides and chlorothalonil analyzed only DCPA could be quantified at six of these sites (2.0 to 10.3 pg/g fresh weight). However, higher levels (6.9 to 85.5 pg/g fresh weight) of the unexpected DCPA structural isomer, dimethyl tetrachlorophthalate (diMe-TCP) were quantified in eggs from all sites. diMe-TCP concentrations tended to be higher in eggs from the Everett Harbor area. As diMe-TCP is not an industrial product, and not commercially available, the source of diMe-TCP is unclear. Regardless, these findings indicate that DCPA and diMe-TCP can be accumulated in the food chain of fish-eating osprey, and transferred in ovo to eggs, and thus may be of concern to the health of the developing chick and the general reproductive health of this osprey population. PMID:16707197

  2. Use of controlled release herbicides in waste burial sites

    SciTech Connect

    Burton, F.G.; Cataldo, D.A.; Cline, J.F.; Skiens, W.E.

    1981-07-01

    Controlled-release formulations of herbicides have been applied to the soil in the manner traditional for herbicides: on the surface or mixed into the top few inches of soil. The controlled-release formulation allows another option that we propose to use: to place herbicides, contained in controlled-release formulations, in a layer at least a foot below the surface of the soil, in order to prevent root penetration below that level. Ideally, the herbicide will prevent root tip cell division but will not translocate within the plant, thus assuring that the plant will survive, preserving the ground cover. Trifluralin is one of the herbicides which does not translocate and was chosen for use in this study. A number of applications for this technology are possible; particularly in waste management. In the present studies, we used two different forms of polymeric carrier/delivery (PCD) systems to investigate the controlled release of herbicides. In the initial study, a sheet was made of homogeneous mixtures of an individual polymer and trifluralin. We made several of these sheets, using a different polymer each time (with trifluralin) to compare release rates from the various polymers. We also fabricated cylindrical pellets in two sizes from mixtures of Profax/sup a/ PS-1600 polypropylene and trifluralin, formulated to determine the interaction of PCD systems with soil. Also developed is a trifluralin-releasing device with a theoretical effective lifetime approaching 100 years. The system was designed specifically to protect the asphalt layer or clay/aggregate barriers on uranium mill tailings piles. PCD devices composed of pellets could also be implanted over burial sites for radioactive and/or toxic materials, preventing translocation of those materials to plant shoots, and thence into the biosphere.

  3. Residual herbicide study on selected Hanford Site roadsides

    SciTech Connect

    Smith, J.L.; Kemp, C.J.; Sackschewsky, M.R.

    1993-08-01

    Westinghouse Hanford Company routinely treats roadsides with herbicides to control undesirable plant growth. An experiment was conducted to test perennial grass germination in soils adjacent to roadways of the Hanford Site. The primary variable was the distance from the roadside. A simple germination test was executed in a controlled-environment chamber to determine the residual effects of these applications. As expected, the greatest herbicide activity was found directly adjacent to the roadway, approximately 0 to 20 ft (0 to 6.3 m) from the roadway.

  4. Natural attenuation of chloroacetinilide herbicides in aquatic systems

    USGS Publications Warehouse

    Graham, D.W.; Graham, W.H.; DeNoyelles, F., Jr.; Smith, V.H.

    1999-01-01

    A 4-yr research program that studied the transformation of alachlor and metolachlor in aquatic systems using field microcosms is presented. The field microcosms provided an accurate simulation of natural ecosystems while also permitting the controlled creation of numerous contamination scenarios and sufficient replication to allow statistical evaluation of the results. Different treatments were assessed including conditions as diverse as anaerobic, eutrophic waters typical of nutrient-rich wetland to aerobic, oligotrophic waters typical of the epilimnion of Canadian glacial lake. Herbicide transformation rate was most strongly affected by water temperature, oxygen conditions, nutrient levels within the system, and the specific herbicide assessed.

  5. Disease associated with exposure to certain herbicide agents: peripheral neuropathy.

    PubMed

    2013-09-01

    The Department of Veterans Affairs (VA) adopts as a final rule its proposal to amend its adjudication regulations by clarifying and expanding the terminology regarding presumptive service connection for acute and subacute peripheral neuropathy associated with exposure to certain herbicide agents. This amendment implements a decision by the Secretary of Veterans Affairs based on findings from the National Academy of Sciences (NAS) Institute of Medicine report, Veterans and Agent Orange: Update 2010. It also amends VA's regulation governing retroactive awards for certain diseases associated with herbicide exposure as required by court orders in the class action litigation of Nehmer v. U.S. Department of Veterans Affairs. PMID:24040683

  6. Optimized liquid chromatography tandem mass spectrometry approach for the determination of diquat and paraquat herbicides.

    PubMed

    Hao, Chunyan; Zhao, Xiaoming; Morse, David; Yang, Paul; Taguchi, Vince; Morra, Franca

    2013-08-23

    Liquid chromatography tandem mass spectrometry (LC-MS/MS) determination of quaternary ammonium herbicides diquat (DQ) and paraquat (PQ) can be very challenging due to their complicated chromatographic and mass spectrometric behaviors. Various multiple reaction monitoring (MRM) transitions from radical cations M(+) and singly charged cations [M-H](+), have been reported for LC-MS/MS quantitation under different chromatographic and mass spectrometric conditions. However, interference peaks were observed for certain previously reported MRM transitions in our study. Using a Dionex Acclaim(®) reversed-phase and HILIC mixed-mode LC column, we evaluated the most sensitive MRM transitions from three types of quasi-molecular ions of DQ and PQ, elucidated the cross-interference phenomena, and demonstrated that the rarely mentioned MRM transitions from dications M(2+) offered the best selectivity for LC-MS/MS analysis. Experimental parameters, such as IonSpray (IS) voltage, source temperature, declustering potential (DP), column oven temperature, collision energy (CE), acid and salt concentrations in the mobile phases were also optimized and an uncommon electrospray ionization (ESI) capillary voltage of 1000V achieved the highest sensitivity. Employing the proposed dication transitions 92/84.5 for DQ and 93/171 for PQ, the direct aqueous injection LC-MS/MS method developed was able to provide a method detection limit (MDL) of 0.1μg/L for the determination of these two herbicides in drinking water. PMID:23871562

  7. Demographics, Clinical Characteristics and Management of Herbicide Poisoning in Tertiary Care Hospital

    PubMed Central

    Cherukuri, Harika; Pramoda, K.; Rohini, D.; Thunga, Girish; Vijaynarayana, K.; Sreedharan, N.; Varma, Muralidhar; Pandit, Vinay

    2014-01-01

    Herbicide poisoning is most common method of suicide in India and it is associated with high morbidity and mortality. Among different herbicidal poisonings the most predominantly found poisonings are paraquat and glyphosate. These compounds are highly toxic and their poisonings require proper management techniques. High fatality is seen in these cases which are mainly due to its inherent toxicity and lack of effective treatment. Common symptoms of these poisonings includes gastrointestinal corrosive effects with mouth and throat, epigastric pain and dysphagia, acid-base imbalance, pulmonary edema, shock and arrhythmia. Long term health effects include pulmonary fibrosis, renal failure, hepatic failure, heart failure, multi-organ failure or death. No proven antidote exists for these poisonings. So the treatment is mainly supportive. Initially gastric lavage or whole-gut irrigation using adsorbents such as Fuller's earth, bentonite or activated charcoal is recommended. In case of renal failure hemodialysis or hemoperfusion may be considered. However novel approaches like treatment with N-acetylcysteine, vitamin C, vitamin E, cyclophosphamide may also be helpful. PMID:25253933

  8. Demographics, clinical characteristics and management of herbicide poisoning in tertiary care hospital.

    PubMed

    Cherukuri, Harika; Pramoda, K; Rohini, D; Thunga, Girish; Vijaynarayana, K; Sreedharan, N; Varma, Muralidhar; Pandit, Vinay

    2014-05-01

    Herbicide poisoning is most common method of suicide in India and it is associated with high morbidity and mortality. Among different herbicidal poisonings the most predominantly found poisonings are paraquat and glyphosate. These compounds are highly toxic and their poisonings require proper management techniques. High fatality is seen in these cases which are mainly due to its inherent toxicity and lack of effective treatment. Common symptoms of these poisonings includes gastrointestinal corrosive effects with mouth and throat, epigastric pain and dysphagia, acid-base imbalance, pulmonary edema, shock and arrhythmia. Long term health effects include pulmonary fibrosis, renal failure, hepatic failure, heart failure, multi-organ failure or death. No proven antidote exists for these poisonings. So the treatment is mainly supportive. Initially gastric lavage or whole-gut irrigation using adsorbents such as Fuller's earth, bentonite or activated charcoal is recommended. In case of renal failure hemodialysis or hemoperfusion may be considered. However novel approaches like treatment with N-acetylcysteine, vitamin C, vitamin E, cyclophosphamide may also be helpful. PMID:25253933

  9. Environmental Fate of Chiral Herbicide Fenoxaprop-ethyl in Water-Sediment Microcosms

    NASA Astrophysics Data System (ADS)

    Jing, Xu; Yao, Guojun; Liu, Donghui; Liu, Mingke; Wang, Peng; Zhou, Zhiqiang

    2016-05-01

    The environmental fate of the herbicide fenoxaprop-ethyl (FE) in water, sediment and water-sediment microcosm was studied and degradation products fenoxaprop (FA), ethyl-2-(4-hydroxyphenoxy)propanoate (EHPP), 2-(4-hydroxyphenoxy)propanoic acid (HPPA) and 6-chloro-2,3-dihydrobenzoxazol-2-one (CDHB) were monitored. FE, FA, EHPP and HPPA were chiral and the environmental behavior was investigated on an enantiomeric level. In water, sediment and water-sediment microcosms, fenoxaprop-ethyl degraded very fast with half-lives less than 1 day and it was found the herbicidally inactive S-enantiomer degraded faster. Fenoxaprop was the main primary degradation product which was quickly formed and the further degradation was relatively slow with half-lives of 6.4–12.4 days, and the S-enantiomer degraded faster too. EHPP, HPPA and CDHB could be found and S-EHPP and S-HPPA were degraded preferentially. The effects of microorganism and water content were investigated and it was found that the enantioselectivity was attributed to microorganisms. In sediment, the main degradation pathway of fenoxaprop-ethyl was hydrolysis and the degradation rate of fenoxaprop-ethyl increased with water content. The degradation products and enantioselectivity should be considered for the impact of fenoxaprop-ethyl on the aquatic system.

  10. Environmental Fate of Chiral Herbicide Fenoxaprop-ethyl in Water-Sediment Microcosms.

    PubMed

    Jing, Xu; Yao, Guojun; Liu, Donghui; Liu, Mingke; Wang, Peng; Zhou, Zhiqiang

    2016-01-01

    The environmental fate of the herbicide fenoxaprop-ethyl (FE) in water, sediment and water-sediment microcosm was studied and degradation products fenoxaprop (FA), ethyl-2-(4-hydroxyphenoxy)propanoate (EHPP), 2-(4-hydroxyphenoxy)propanoic acid (HPPA) and 6-chloro-2,3-dihydrobenzoxazol-2-one (CDHB) were monitored. FE, FA, EHPP and HPPA were chiral and the environmental behavior was investigated on an enantiomeric level. In water, sediment and water-sediment microcosms, fenoxaprop-ethyl degraded very fast with half-lives less than 1 day and it was found the herbicidally inactive S-enantiomer degraded faster. Fenoxaprop was the main primary degradation product which was quickly formed and the further degradation was relatively slow with half-lives of 6.4-12.4 days, and the S-enantiomer degraded faster too. EHPP, HPPA and CDHB could be found and S-EHPP and S-HPPA were degraded preferentially. The effects of microorganism and water content were investigated and it was found that the enantioselectivity was attributed to microorganisms. In sediment, the main degradation pathway of fenoxaprop-ethyl was hydrolysis and the degradation rate of fenoxaprop-ethyl increased with water content. The degradation products and enantioselectivity should be considered for the impact of fenoxaprop-ethyl on the aquatic system. PMID:27225540

  11. Environmental Fate of Chiral Herbicide Fenoxaprop-ethyl in Water-Sediment Microcosms

    PubMed Central

    Jing, Xu; Yao, Guojun; Liu, Donghui; Liu, Mingke; Wang, Peng; Zhou, Zhiqiang

    2016-01-01

    The environmental fate of the herbicide fenoxaprop-ethyl (FE) in water, sediment and water-sediment microcosm was studied and degradation products fenoxaprop (FA), ethyl-2-(4-hydroxyphenoxy)propanoate (EHPP), 2-(4-hydroxyphenoxy)propanoic acid (HPPA) and 6-chloro-2,3-dihydrobenzoxazol-2-one (CDHB) were monitored. FE, FA, EHPP and HPPA were chiral and the environmental behavior was investigated on an enantiomeric level. In water, sediment and water-sediment microcosms, fenoxaprop-ethyl degraded very fast with half-lives less than 1 day and it was found the herbicidally inactive S-enantiomer degraded faster. Fenoxaprop was the main primary degradation product which was quickly formed and the further degradation was relatively slow with half-lives of 6.4–12.4 days, and the S-enantiomer degraded faster too. EHPP, HPPA and CDHB could be found and S-EHPP and S-HPPA were degraded preferentially. The effects of microorganism and water content were investigated and it was found that the enantioselectivity was attributed to microorganisms. In sediment, the main degradation pathway of fenoxaprop-ethyl was hydrolysis and the degradation rate of fenoxaprop-ethyl increased with water content. The degradation products and enantioselectivity should be considered for the impact of fenoxaprop-ethyl on the aquatic system. PMID:27225540

  12. Functional and structural characterization of two Bacillus megaterium nitroreductases biotransforming the herbicide mesotrione.

    PubMed

    Carles, Louis; Besse-Hoggan, Pascale; Joly, Muriel; Vigouroux, Armelle; Moréra, Solange; Batisson, Isabelle

    2016-05-15

    Mesotrione is a selective herbicide belonging to the triketone family, commonly used on maize cultures since 2003. A mesotrione-transforming Bacillus megaterium Mes11 strain isolated from an agricultural soil was used as a model to identify the key enzymes initiating the biotransformation of this herbicide. Two enzymes (called NfrA1 and NfrA2/YcnD) were identified, and functionally and structurally characterized. Both belong to the NfsA FRP family of the nitro-FMN reductase superfamily (type I oxygen-insensitive nitroreductase) and show optimal pH and temperature of 6-6.5 and 23-25°C, respectively. Both undergo a Ping Pong Bi Bi mechanism, with NADPH and NADPH/NADH as cofactors for NfrA1 and NfrA2/YcnD, respectively. It is interesting that both can also reduce various nitro compounds including pesticides, antibiotics, one prodrug and 4-methylsulfonyl-2-nitrobenzoic acid, one of the mesotrione metabolites retrieved from the environment. The present study constitutes the first identification of mesotrione-transforming enzymes. These enzymes (or their corresponding genes) could be used as biomarkers to predict the capacity of ecosystems to transform mesotrione and assess their contamination by both the parent molecule and/or the metabolites. PMID:27005432

  13. Crystal structures of two novel sulfonylurea herbicides in complex with Arabidopsis thaliana acetohydroxyacid synthase

    SciTech Connect

    Wang, Jian-Guo; Lee, Patrick K.-M.; Dong, Yu-Hui; Pang, Siew Siew; Duggleby, Ronald G.; Li, Zheng-Ming; Guddat, Luke W.

    2009-08-17

    Acetohydroxyacid synthase (AHAS; EC 2.2.1.6) is the first enzyme in the biosynthetic pathway of the branched-chain amino acids. It catalyzes the conversion of two molecules of pyruvate into 2-acetolactate or one molecule of pyruvate and one molecule of 2-ketobutyrate into 2-aceto-2-hydroxybutyrate. AHAS requires the cofactors thiamine diphosphate (ThDP), Mg{sup 2+} and FAD for activity. The herbicides that target this enzyme are effective in protecting a broad range of crops from weed species. However, resistance in the field is now a serious problem worldwide. To address this, two new sulfonylureas, monosulfuron and monosulfuron ester, have been developed as commercial herbicides in China. These molecules differ from the traditional sulfonylureas in that the heterocyclic ring attached to the nitrogen atom of the sulfonylurea bridge is monosubstituted rather than disubstituted. The structures of these compounds in complex with the catalytic subunit of Arabidopsis thaliana AHAS have been determined to 3.0 and 2.8 {angstrom}, respectively. In both complexes, these molecules are bound in the tunnel leading to the active site, such that the sole substituent of the heterocyclic ring is buried deepest and oriented towards the ThDP. Unlike the structures of Arabidopsis thaliana AHAS in complex with the classic disubstituted sulfonylureas, where ThDP is broken, this cofactor is intact and present most likely as the hydroxylethyl intermediate.

  14. The effect of alginite on the decomposition of the herbicide propisochlor.

    PubMed

    Rauch, Renáta; Földényi, Rita

    2012-01-01

    The catalytic effect of an oil shale rock "alginite" was studied under laboratory conditions on the decomposition of herbicide propisochlor. The breakdown process was followed in four parallel experiments: buffered solution (pH = 7), in buffer solutions containing alginite or bentonite (a common rock) and also in the solution obtained from the extraction of the alginite (alginite/buffer = 1/10). In the aqueous phase, the decomposition of the herbicide was followed by using HPLC-UV and the metabolites of degradation were identified by GC-MS techniques. For the phenomenological description of the experimental decay curves two parallel reactions with first-order kinetics were taken into account. During the time of experiments, no significant decomposition was observed either in the pure buffer solution or in the presence of bentonite. When, however, alginite was added to the system the degradation of propisochlor was accelerated dramatically: after 5 days, its concentration dropped below 50 % of the initial value. The identified degradation products indicate both reductive as well as oxidative biological mechanisms operating under anoxic conditions. It was proved earlier that the sulfenic and sulfinic acid ester derivatives of the propisochlor appeared in the metabolic pathways of animals and plants but they were not detected yet in the degradation process occurring in the soil environment. Among the degradation products a dehydrochlorinated derivative is a new metabolite identified in our experiments. Our results corroborate the algae-related origin of the alginite rock and forecast its application as a soil ameliorating agent. PMID:22560029

  15. Controlled release of the herbicide simazine from computationally designed molecularly imprinted polymers.

    PubMed

    Piletska, Elena V; Turner, Nicholas W; Turner, Anthony P F; Piletsky, Sergey A

    2005-11-01

    The present study describes the development of materials suitable for environmental control of algae. Molecularly imprinted polymers (MIPs) were used as simazine carriers able to provide the controlled release of simazine into water. Three polymers were designed using computational modelling. The selection of methacrylic acid (MA) and hydroxyethyl methacrylate (HEM) as functional monomers was based on results obtained using the Leapfrog algorithm. A cross-linked polymer made without functional monomers was also prepared and tested as a control. The release of simazine from all three polymers was studied. It was shown that the presence of functional monomers is important for polymer affinity and for controlled release of herbicide. The speed of release of herbicide correlated with the calculated binding characteristics. The high-affinity MA-based polymer released approximately 2% and the low-affinity HEM-based polymer released approximately 27% of the template over 25 days. The kinetics of simazine release from HEM-based polymer show that total saturation of an aqueous environment could be achieved over a period of 3 weeks and this corresponds to the maximal simazine solubility in water. The possible use of these types of polymers in the field of controlled release is discussed. PMID:16111783

  16. Dopaminergic toxicity of the herbicide atrazine in rat striatal slices

    PubMed Central

    Filipov, Nikolay M.; Stewart, Molly A.; Carr, Russell L.; Sistrunk, Shannon C.

    2007-01-01

    A possible link between Parkinson’s disease and pesticide exposure has been suggested, and recently it was shown that the herbicide atrazine (ATR) modulates catecholamine metabolism in PC12 cells and affects basal ganglia function in vivo. Hence, the objectives of this study were to: (i) determine if ATR is capable of modulating dopamine (DA) metabolism in striatal tissue slices in vitro and (ii) to explore possible mechanisms of its effects. Striatal tissues from adult male Sprague Dawley rats were incubated with up to 500 μM ATR in a metabolic shaker bath at 37 °C and an atmosphere of 95% O2 and 5% CO2 for 4 h. At the end of incubation, samples were collected for both tissue and media levels of DA and its metabolites (3,4-dihydroxyphenylacetic acid, DOPAC and homovanillic acid, HVA), which were determined by high-performance liquid chromatography with electrochemical detection (HPLC-ECD). To gain some mechanistic insight in to the way ATR affects DA metabolism, several pharmacological manipulations were performed. Striata exposed to ATR at concentrations of 100 μM and greater had a dose-dependent decrease of tissue levels of DA. At doses of ATR 50 μM and greater, the DOPAC+HVA/DA ratio was dose-dependently increased. Tyrosine hydroxylase (TH, the rate-limiting enzyme in DA synthesis) protein levels and activity were not affected by ATR treatment. However, high potassium induced DA release into the medium was decreased, whereas the increase in media DA observed in the presence of the DA uptake inhibitor nomifensine was increased even further by ATR in a dose-dependent manner. All of these effects of ATR were observed at levels that were not toxic to the tissue, as LDH release into the medium (lactate dehydrogenase, an index of non-specific cytotoxicity) was not affected by ATR. Taken together, results from this study suggest that ATR decreases tissue DA levels not by affecting TH activity, but possibly by interfering with the vesicular storage and

  17. Effect of release herbicide on mortality, avoidance response, and growth of amphibian larvae in two forest wetlands.

    PubMed

    Wojtaszek, Barbara F; Buscarini, Teresa M; Chartrand, Derek T; Stephenson, Gerald R; Thompson, Dean G

    2005-10-01

    Effects of Release herbicide (triclopyr butoxyethyl ester, [TBEE]) on mortality, avoidance response, and growth of larval amphibians (Rana clamitans, Rana pipiens) were investigated using in situ enclosures deployed in two forest wetlands in northern Ontario, Canada. Release was applied at nominal concentrations ranging from 0.26 to 7.68 mg TBEE acid equivalents (AE)/L. No significant deleterious effects of this herbicide on larval growth were detected. However, concentration-dependent mortality and abnormal avoidance response were observed. Most mortality occurred within 96 h following treatment. Median lethal concentration (LC50) values for each species and experimental site ranged from 2.79 to 3.29 mg AE/L, while median effective concentration (EC50) values (abnormal avoidance response) ranged from 1.67 to 3.84 mg AE/L. The LC10 and EC10 endpoints approximated aqueous concentrations (0.59 mg AE/L) expected under direct aerial overspray scenarios, indicating a potential risk of impacts for a small proportion of native amphibian larvae. However, given the low frequency and limited use of this herbicide formulation in Canadian forestry, these risks are considered negligible. Changes in usage patterns would require concurrent chemical and biological monitoring of operational spray programs to accurately quantify the probability and magnitude of real-world exposures and to relate these exposure levels to concentration-response relationships including those described in this study. PMID:16268155

  18. Pelargonic acid weed control: Concentrations, adjuvants, and application timing

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pelargonic acid is a fatty acid naturally occurring in many plants, animals, and foods. Pelargonic acid has potential as a broad-spectrum post-emergence or burn-down herbicide for organic crop production. Field research was conducted in southeast Oklahoma (Lane, OK, Atoka County) to determine the ...

  19. THE ECOLOGICAL EFFECTS OF TRICHLORACETIC ACID (TCAA) IN THE ENVIRONMENT

    EPA Science Inventory

    Trichloroacetic acid (TCAA) is a member of the family of compounds known as chloroacetic acids, which includes mono-, di- and trichloroacetic acid. The significant property these compounds share is that they are all phytotoxic. TCAA once was widely used as a potent herbicide. ...

  20. Herbicides and nitrate in near-surface aquifers in the midcontinental United States, 1991

    USGS Publications Warehouse

    Kolpin, Dana W.; Burkart, Michael R.; Thurman, E. Michael

    1994-01-01

    Hydrogeologic factors, land use, agricultural practices, local features, and water chemistry were analyzed for possible relation to herbicide and excess-nitrate detections. Herbicides and excess nitrate were detected more frequently in near-surface unconsolidated aquifers than in nearsurface bedrock aquifers. The depth to the top of the aquifer was inversely related to the frequency of detection of herbicides and excess nitrate. The proximity of streams to sampled wells also affected the frequency of herbicide detection. Significant seasonal differences were determined for the frequency of herbicide detection, but not for the frequency of excess nitrate.

  1. Factors affecting herbicide yields in the Chesapeake Bay watershed, June 1994

    USGS Publications Warehouse

    Hainly, R.A.; Kahn, J.M.

    1996-01-01

    Median concentrations and instantaneous yields of alachlor, metolachlor, atrazine, cyanazine, and simazine were generally highest at sites in the Lower Susquehanna River Basin and in agricultural subbasins. Instantaneous herbicide yields are related to land use, hydrogeologic setting, streamflow yield, and agricultural row cropping practices. The significance of these relations may be affected by the interdependence of the factors. The percentage of basin area planted in corn is the most influential factor in the prediction of herbicide yield. Instantaneous yields of all five herbicides measured in June 1994 related poorly to averaged 199094 herbicide use. Annually averaged herbicide-use data are too general to use as a predictor for short-term herbicide yields. An evaluation of factors affecting herbicide yields could be refined with more-current land use and land cover information and a more accurate estimate of the percentage of basin area planted in corn. Factors related to herbicide yields can be used to predict herbicide yields in other basins within the Chesapeake Bay watershed and to develop an estimate of herbicide loads to Chesapeake Bay.Median concentrations and instantaneous yields of alachlor, metolachlor, atrazine, cyanazine, and simazine were generally highest at sites in the Lower Susquehanna River Basin and in agricultural subbasins. Instantaneous herbicide yields are related to land use, hydrogeologic setting, streamflow yield, and agricultural row cropping practices. The significance of these relations may be affected by the interdependence of the factors. The percentage of basin area planted in corn is the most influential factor in the prediction of herbicide yield. Instantaneous yields of all five herbicides measured in June 1994 related poorly to averaged 1990-94 herbicide use. Annually averaged herbicide-use data are too general to use as a predictor for short-term herbicide yields. An evaluation of factors affecting herbicide yields could

  2. Influence of herbicide active ingredient, nozzle type, orifice size, spray pressure, and carrier volume rate on spray droplet size characteristics

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Recent concerns on herbicide spray drift and its subsequent impact on the surrounding environment and herbicide efficacy have prompted applicators to focus on methods to reduce off-target movement of herbicides. Herbicide applications are complex processes and as such few studies have been conducted...

  3. AHAS herbicide resistance endowing mutations: effect on AHAS functionality and plant growth

    PubMed Central

    Yu, Qin; Han, Heping; Vila-Aiub, Martin M.; Powles, Stephen B.

    2010-01-01

    Twenty-two amino acid substitutions at seven conserved amino acid residues in the acetohydroxyacid synthase (AHAS) gene have been identified to date that confer target-site resistance to AHAS-inhibiting herbicides in biotypes of field-evolved resistant weed species. However, the effect of resistance mutations on AHAS functionality and plant growth has been investigated for only a very few mutations. This research investigates the effect of various AHAS resistance mutations in Lolium rigidum on AHAS functionality and plant growth. The enzyme kinetics of AHAS from five purified L. rigidum populations, each homozygous for the resistance mutations Pro-197-Ala, Pro-197-Arg, Pro-197-Gln, Pro-197-Ser or Trp-574-Leu, were characterized and the pleiotropic effect of three mutations on plant growth was assessed via relative growth rate analysis. All these resistance mutations endowed a herbicide-resistant AHAS and most resulted in higher extractable AHAS activity, with no-to-minor changes in AHAS kinetics. The Pro-197-Arg mutation slightly (but significantly) increased the Km for pyruvate and remarkably increased sensitivity to feedback inhibition by branched chain amino acids. Whereas the Pro-197-Ser and Trp-574-Leu mutations exhibited no significant effects on plant growth, the Pro-197-Arg mutation resulted in lower growth rates. It is clear that, at least in L. rigidum, these five AHAS resistance mutations have no major impact on AHAS functionality and hence probably no plant resistance costs. These results, in part, explain why so many Pro-197 AHAS resistance mutations in AHAS have evolved and why the Pro-197-Ser and the Trp-574-Leu AHAS resistance mutations are frequently found in many weed species. PMID:20627897

  4. Effects of herbicide-treated host plants on the development of Mamestra brassicae L. caterpillars.

    PubMed

    Hahn, Melanie; Geisthardt, Martin; Brühl, Carsten A

    2014-11-01

    Herbicides are widely used pesticides that affect plants by changing their chemistry. In doing so, herbicides might also influence the quality of plants as food for herbivores. To study the effects of herbicides on host plant quality, 3 plant species (Plantago lanceolata L., P. major L., and Ranunculus acris L.) were treated with sublethal rates of either a sulfonylurea (Atlantis WG, Bayer CropScience) or a glyphosate (Roundup LB Plus, Monsanto) herbicide, and the development of caterpillars of the cabbage moth Mamestra brassicae L. that fed on these plants was observed. Of the 6 tested plant-herbicide combinations, 1 combination (R. acris + sulfonylurea herbicide) resulted in significantly lower caterpillar weight, increased time to pupation, and increased overall development time compared with larvae that were fed unsprayed plants. These results might be caused by a lower nutritional value of these host plants or increased concentrations of secondary metabolites that are involved in plant defense. The results of the present and other studies suggest potential risks to herbivores that feed on host plants treated with sublethal rates of herbicides. However, as the effects of herbicides on host plant quality appear to be species-specific and as there are numerous plant-herbicide-herbivore relationships in agricultural landscapes, a general reduction in herbicide contamination of nontarget habitats (e.g., field margins) might mitigate the negative effects of herbicides on host plant quality. PMID:25143001

  5. Determination of chloroacetanilide herbicide metabolites in water using high-performance liquid chromatography-diode array detection and high-performance liquid chromatography/mass spectrometry

    USGS Publications Warehouse

    Hostetler, K.A.; Thurman, E.M.

    2000-01-01

    Analytical methods using high-performance liquid chromatography-diode array detection (HPLC-DAD) and high-performance liquid chromatography/mass spectrometry (HPLC/MS) were developed for the analysis of the following chloroacetanilide herbicide metabolites in water: alachlor ethanesulfonic acid (ESA); alachlor oxanilic acid; acetochlor ESA; acetochlor oxanilic acid; metolachlor ESA; and metolachlor oxanilic acid. Good precision and accuracy were demonstrated for both the HPLC-DAD and HPLC/MS methods in reagent water, surface water, and ground water. The average HPLC-DAD recoveries of the chloroacetanilide herbicide metabolites from water samples spiked at 0.25, 0.5 and 2.0 ??g/l ranged from 84 to 112%, with relative standard deviations of 18% or less. The average HPLC/MS recoveries of the metabolites from water samples spiked at 0.05, 0.2 and 2.0 ??g/l ranged from 81 to 118%, with relative standard deviations of 20% or less. The limit of quantitation (LOQ) for all metabolites using the HPLC-DAD method was 0.20 ??g/l, whereas the LOQ using the HPLC/MS method was at 0.05 ??g/l. These metabolite-determination methods are valuable for acquiring information about water quality and the fate and transport of the parent chloroacetanilide herbicides in water. Copyright (C) 2000 Elsevier Science B.V.

  6. Herbicides in ground water of the Midwest: A regional study of shallow aquifers, 1991-94

    USGS Publications Warehouse

    Kolpin, Dana W.; Stamer, J.K.; Goolsby, D.A.; Thurman, E.M.

    1998-01-01

    The intensive herbicide use associated with the 'Corn Belt' marks the Midwestern United States as a region where herbicide contamination of ground water could be a problem. To better understand the regional occurrence of herbicides in shallow aquifers of the Midwest, a sampling network of 303 wells across 12 States was developed. The results documented relatively widespread, low-level concentrations of herbicides in the shallow aquifers sampled. The most frequently detected compounds, however, were the transformation products of these herbicides. A relation was determined between herbicide occurrence and the general age of the ground water sampled. Water that recharged ground water within the past 40 years was much more likely to contain herbicides than water recharged earlier.

  7. Pollen Expression of Herbicide Target Site Resistance Genes in Annual Ryegrass (Lolium rigidum).

    PubMed Central

    Richter, J.; Powles, S. B.

    1993-01-01

    Herbicide resistance can occur either through target-site insensitivity or by nontarget site-based mechanisms. Two herbicide-resistant biotypes of Lolium rigidum Gaud., one resistant to acetolactate synthase (ALS)-inhibiting herbicides (biotype WLR1) and the other resistant to acetyl CoA carboxylase (ACCase)-inhibiting herbicides (biotype WLR96) through target-site insensitivity at the whole plant and enzymic levels, were found to express this resistance in the pollen. Pollen produced by resistant biotypes grew uninhibited when challenged with herbicide, whereas that from a susceptible biotype was inhibited. A third biotype, SLR31, resistant to ACCase-inhibiting and certain ALS-inhibiting herbicides at the whole plant level through nontarget site-based mechanisms, did not exhibit this expression in the pollen. The technique described may form the basis for a rapid screen for certain nuclear-encoded, target site-based herbicide-resistance mechanisms. PMID:12231886

  8. Effects of Certain Herbicides and Their Combinations on Nitrate and Nitrite Reduction 1

    PubMed Central

    Klepper, Lowell A.

    1979-01-01

    A study was made concerning the effect of various herbicides, when used alone or in combination, on nitrite accumulation in excised leaves of wheat (Triticum aestivum L., var. `Centurk'). Treatment of leaves with photosynthetic inhibitor herbicides, known to interfere with the transfer of light energy, caused accumulation of nitrite under illuminated, aerobic conditions. When certain other herbicides, which do not interfere with the photosynthetic process, were applied to leaves and incubated under dark, aerobic conditions, nitrite accumulations were enhanced over those treated with photosynthetic inhibitors or the controls. The combination of photosynthetic inhibitor herbicides and certain other “nonphotosynthetic inhibitor” herbicides caused relatively large amounts of nitrite to accumulate in light or in darkness. Nitrite accumulation occurs when nitrate and nitrite reduction are not in balance. The proposed actions of the herbicides used in this study are discussed. This discussion provides a rationale for the accumulation of nitrite by the herbicide-treated leaves. PMID:16660947

  9. The Metabolites of the Herbicide L-Phosphinothricin (Glufosinate) (Identification, Stability, and Mobility in Transgenic, Herbicide-Resistant, and Untransformed Plants).

    PubMed Central

    Droge-Laser, W.; Siemeling, U.; Puhler, A.; Broer, I.

    1994-01-01

    The metabolism of the herbicide L-phosphinothricin (L-Pt) was analyzed in tobacco (Nicotiana tabacum), alfalfa (Medicago sativa), and carrot (Daucus carota). In transgenic, Pt-resistant plants expressing the Pt-N-acetyltransferase gene (pat), L-Pt was acetylated, resulting in two forms of N-acetyl-Pt (ac-Pt). In transgenic plants expressing only low pat-encoded acetylating activity as well as in genetically unmodified plants, three metabolic compounds 4-methylphosphinico-2-oxo-butanoic acid, 3-methylphosphinico-propanoic acid (MPP), and 4-methylphosphinico-2-hydroxy-butanoic acid (MHB) were identified. Hence, the transgene-encoded acetylation of L-Pt competes with a plant-specific degradation. The compounds MPP, MHB, and ac-Pt were found to be the final, stable products of the plant's metabolic pathways. The mobility of these stable compounds in the plant was investigated: L-Pt as well as the derived metabolites were found to be preferentially transported to the upper regions of the plant. PMID:12232195

  10. Preemergence herbicides forpotential use in potato (Solanum tuberosum) production

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Field trials were conducted in 2009 and 2010 near Paterson, WA and Ontario, OR to evaluate weed control and potato tolerance to preemergence applied pyroxasulfone, saflufenacil, and KSU12800 herbicides. Pyroxasulfone at 0.09 to 0.15 kg ai ha-1 and saflufenacil at 0.05 to 0.07 kg ha-1 applied PRE alo...

  11. Analysis of Herbicide Transport from Goodwater Creek Experimental Watershed

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Environmental impacts caused by herbicide loss from agricultural production are well documented in the surface runoff-prone claypan region. The most widely known impact was for atrazine, which caused the Mark Twain Lake to be listed in the original 303(d) list for impaired waters. While this lake ha...

  12. PRENATAL EFFECTS OF HERBICIDES: EVALUATION BY THE PRENATAL DEVELOPMENT INDEX

    EPA Science Inventory

    The herbicides 2,4-D and 2,4,5-T and many of the esters of these compounds produced cleft palates in CD-1 mice. Silvex and Agent Orange also produced cleft palates. Depending on the dose and means of administration variable responses relating to the production of cleft palates, e...

  13. Assessing off-taraget impacts of herbicide drift on plants

    EPA Science Inventory

    Plants and plant communities provide vital economic services including production of food and fiber crops for direct human consumption and ecosystem services including wildlife habitat and cycling of nutrients and energy. These services can be impacted if herbicides drift from t...

  14. Cotton Response to Herbicide Technologies, Row Patterns, and Tillage Systems

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cotton producers must make decisions related to cotton varieties, herbicide systems, tillage systems, and row patterns. A study was conducted to compare a conventional variety, a glyphosate tolerant variety, and a glufosinate tolerant variety in both conventional tillage and conservation tillage sys...

  15. NEGATIVE-ION MASS SPECTROMETRY OF SULFONYLUREA HERBICIDES

    EPA Science Inventory

    Sulfonylurea herbicides have been studied using neg-ion desorption chem.-ionization (DCI) mass spectrometry (MS) and DCI-MS/MS techniques. Both {M-H]- and M.- ions were obsd. in the DCI mass spectra. The collisonally activated dissocn. (CAD) spectra were characteristic of the str...

  16. Effect of preemergence herbicides on early seeded watermelon

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Herbicides approved for watermelon may result in crop injury under cool or wet conditions. To obtain market prices associated with early harvest, planting may occur when conditions are sub optimal for seed germination and plant growth. Consequently, early planting may contribute to crop injury fro...

  17. Citrullus Germplasm Lines Vary in Clomazone Herbicide Tolerance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Differences between Citrullus germplasm lines in clomazone injury were first observed when the herbicide was used for weed control in fields containing germplasm lines of watermelon breeding project at the U.S. Vegetable Laboratory, Charleston, SC. The objectives of this investigation were to asses...

  18. Modelling the effect of fluctuating herbicide concentrations on algae growth.

    PubMed

    Copin, Pierre-Jean; Coutu, Sylvain; Chèvre, Nathalie

    2015-03-01

    Herbicide concentrations fluctuate widely in watercourses after crop applications and rain events. The level of concentrations in pulses can exceed the water chronic quality criteria. In the present study, we proposed modelling the effects of successive pulse exposure on algae. The deterministic model proposed is based on two parameters: (i) the typical growth rate of the algae, obtained by monitoring growth rates of several successive batch cultures in growth media, characterizing both the growth of the control and during the recovery periods; (ii) the growth rate of the algae exposed to pulses, determined from a dose-response curve obtained with a standard toxicity test. We focused on the herbicide isoproturon and on the freshwater alga Scenedesmus vacuolatus, and we validated the model prediction based on effect measured during five sequential pulse exposures in laboratory. The comparison between the laboratory and the modelled effects illustrated that the results yielded were consistent, making the model suitable for effect prediction of the herbicide photosystem II inhibitor isoproturon on the alga S. vacuolatus. More generally, modelling showed that both pulse duration and level of concentration play a crucial role. The application of the model to a real case demonstrated that both the highest peaks and the low peaks with a long duration affect principally the cell density inhibition of the alga S. vacuolatus. It is therefore essential to detect these characteristic pulses when monitoring of herbicide concentrations are conducted in rivers. PMID:25499055

  19. Herbicide hormesis-can it be useful in crop production

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The yield-enhancing effects of some pesticides may change the focus in their use in crop production, from crop protection to crop enhancement. While such beneficial uses of pesticides are specifically en vogue for fungicides and seed treatments, the use of herbicides for crop enhancement has not yet...

  20. Reactions of Sweet Corn Hybrids to Prevalent Diseases and Herbicides

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This 27-year summary is of University of Illinois sweet corn nurseries from 1984 to 2010, and includes the reactions of 800 hybrids to eight diseases and three herbicides. Commercially-available and pre-commercial hybrids included 547 shrunken-2 hybrids (317 yellow, 152 bi-color, and 78 white), 117 ...