Science.gov

Sample records for phytophthora ramorum em

  1. Phytophthora ramorum

    USDA-ARS?s Scientific Manuscript database

    Phytophthora ramorum is a recently emerged plant pathogen and causal agent of one of the most destructive and devastating diseases currently affecting US horticulture and forests. Formally described in 2001, P. ramorum is a filamentous, diploid protozoan that is one of 117 currently recognized Phyto...

  2. Phytophthora ramorum

    Treesearch

    J. L. Parke; D. M. Rizzo

    2011-01-01

    P. ramorum Werres, De Cock, & Man in't Veld (2001) appears to be an exotic species introduced from an unknown origin to Europe and western N. America in the mid-1990s, likely on nursery plants (Mascheretti et al. 2008). In California and southwest Oregon, the pathogen spread to native oak and...

  3. Canadian Phytophthora ramorum 2006 update

    Treesearch

    Ken Wong

    2008-01-01

    Annual national surveys for Phytophthora ramorum have been conducted in Canada since 2002. Over 37,361 samples were taken in 2006, which focused on 251 wholesale and retail nurseries across Canada that were either growers or importers of host plants. In 2006, the national survey detected P. ramorum at one wholesale and four retail...

  4. Population structure of Phytophthora ramorum in Oregon

    Treesearch

    Simone Prospero; Jennifer Britt; Niklaus Grünwald; Everett Hansen

    2008-01-01

    Phytophthora ramorum is infecting plants in Oregon forests and nurseries. In this study, we analyzed the population structure of the P. ramorum in Oregon from 2001 to 2004 using microsatellites. The P. ramorum population in Oregon is characterized by low genetic diversity, significant genetic differences between...

  5. Fungicide control of Phytophthora ramorum on rhododendron

    Treesearch

    Kurt Heungens; Isabelle De Dobbelaere; Martine Maes

    2006-01-01

    Commercial rhododendron plants have been the most important hosts of Phytophthora ramorum in Europe. As part of the European Union (EU) emergency phytosanitary measures 2002/757/EU and 2004/426/EU all commercial rhododendron-growing premises are surveyed for P. ramorum. Detection of P. ramorum leads to quarantine...

  6. Molecular identification and detection of Phytophthora ramorum

    Treesearch

    Peter Bonants; Els Verstappen; Ineke De Vries; Katarzyna Wiejacha; Kelly Ivors

    2006-01-01

    The genus Phytophthora comprises over 70 described species, however many new species have been reported recently as a result of the discovery of previously undetected species or by the hybridization of known species. Phytophthora ramorum, one of the new Phytophthora species, is considered a high phytosanitary...

  7. Unstable aneuploid progenies of Phytophthora ramorum

    Treesearch

    Annelies Vercauteren; Xavier Boutet; Anne Chandelier; Kurt Heungens; Martine Maes

    2010-01-01

    Phytophthora ramorum has three populations belonging to the same species: the two North American populations (NA1 and NA2) and the European population (EU1). All three populations are genetically distinct lineages, as revealed by different molecular marker systems. P. ramorum is also heterothallic, with two opposite mating...

  8. New insights into the ecology of Phytophthora ramorum in streams

    Treesearch

    Kamyar Aram; David M. Rizzo

    2013-01-01

    Many Phytophthora species, including Phytophthora ramorum, have been reported from surface waters such as canals, streams, rivers, ponds, and reservoirs, often in association with infested agricultural or natural landscapes (Hong and Moorman 2005). Phytophthora species are recovered with regularity and...

  9. Phytophthora ramorum disease transmission from artificially infested potting media

    Treesearch

    Jennifer L. Parke; Melody L. Roth; Carrie Lewis; Caroline J. Choquette

    2006-01-01

    Potted rhododendrons grown in potting media amended with inoculum of Phytophthora ramorum became infected and showed symptoms of stem necrosis, leaf wilting, and death. P. ramorum was isolated from roots and stems of infected plants.

  10. Geographical distribution of Phytophthora ramorum in Norway

    Treesearch

    María- Luz Herrero; Brita Toppe; Trond Rafoss

    2008-01-01

    In November 2002, Phytophthora ramorum was detected for the first time in Norway. It was isolated from Rhododendron catawbiense imported earlier the same year. After the first detection, the Norwegian Food Safety Authority has carried out surveys from 2003 to 2006. The surveys were first directed to nurseries and garden centres....

  11. How does Phytophthora ramorum infect Rhododendron leaves?

    Treesearch

    Sabine Werres; Marko Riedel

    2013-01-01

    In most parts of Europe, rhododendron is the most important host for the spread of Phytophthora ramorum. To get a better knowledge of leaf infection and capacity for sporulation, infection studies were carried out. Detached leaves of the Rhododendron cultivar 'Catawbiense Grandiflorum' (CG) and the R. insigne hybrid `...

  12. Sporulation on plant roots by Phytophthora ramorum

    USDA-ARS?s Scientific Manuscript database

    Phytophthora ramorum has been shown to infect the roots of many of the pathogen’s foliar hosts. Methods of detecting inoculum in runoff and of quantifying root colonization were tested using Viburnum tinus, Camellia oleifera, Quercus prinus, Umbellularia californica, and Epilobium ciliatum. Plants...

  13. The status of Phytophthora ramorum in Ireland

    Treesearch

    Carmel O?Connor; Elizabeth Gosling

    2008-01-01

    This paper reports on the first 2 years of data collected to study the ecology of Phytophthora ramorum in Ireland. Since spring 2005, sampling has been carried out for the presence of the pathogen in soil and watercourses from 11 susceptible forest sites in Ireland, using a rapid DNA method in conjunction with morphological identification methods....

  14. Mating of Phytophthora ramorum: functionality and consequences

    Treesearch

    Xavier Boutet; Annelies Vercauteren; Chandelier Heungens; Anne Kurt

    2010-01-01

    Phytophthora ramorum (Werres, De Cock, Man in’t Veld), which causes “sudden oak death” in the United States and dieback and leaf necrosis in ornamental plants (mainly Rhododendron and Viburnum) in Europe, is a heterothallic species with two mating types, A1 and A2 (Werres and others 2001, Rizzo and...

  15. Genetic diversity of Phytophthora ramorum in Belgium

    Treesearch

    Annelies Vercauteren; Isabelle De Dobbelaere; Martine Maes; Kurt Heungens

    2010-01-01

    Phytophthora ramorum is thought to be an introduced pathogen in North America and in Europe based on the presence of only three clonal lineages. The North American lineages (NA1 and NA2) are responsible for infections in North American forests and nurseries, while the European lineage (EU1) is responsible for infections in Europe, mostly in...

  16. Forest treatment strategies for Phytophthora ramorum

    Treesearch

    Yana Valachovic; Chris Lee; Jack Marshall; Hugh. Scanlon

    2010-01-01

    Although there is no known cure or preventative on a landscape scale for sudden oak death (SOD), the plant disease caused by Phytophthora ramorum, a variety of management options has been tested with the goal of developing an integrated program of treatment for the pathogen. This paper presents a first attempt to gather together individual...

  17. Update on diagnostics for Phytophthora ramorum

    Treesearch

    Philip Berger

    2006-01-01

    Diagnostics used by the U.S. Department of Agriculture (USDA), to determine absence or presence of Phytophthora ramorum in plant samples, are based on a combination of tests and depend on collaboration with external laboratories. The system currently in place attempts to maximize limited resources and at the same time provide the most scientifically...

  18. Coast live oak resistance to Phytophthora ramorum

    Treesearch

    B.A. McPherson; David L. Wood; Sylvia R. Mori; Pierluigi Bonello

    2012-01-01

    The oomycete Phytophthora ramorum is a plant pathogen with an unusually broad host range. Recognized in 2000 as a previously unknown and likely introduced species, this pathogen has become established in central and northern coastal California, southwestern Oregon, and Western Europe. Tree species that may be killed by stem cankers include true...

  19. APHIS Phytophthora ramorum regulatory strategy for nurseries

    Treesearch

    Jonathan M. Jones

    2006-01-01

    A review of the U. S. Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) regulatory response to Phytophthora ramorum is presented as it impacts nurseries and the nursery industry. The Agency responded in 2004 with three Federal Orders, each more restrictive than the previous one because the appropriate response called...

  20. Process and pattern in the emergence of Phytophthora ramorum

    Treesearch

    Niklaus J. Grüwald; Matteo Garbelotto; Erica M. Goss; Kurt Heungens; Simone Prospero

    2013-01-01

    The invasive sudden oak death pathogen, Phytophthora ramorum, has emerged repeatedly since its first detection in the 1990s in the United States and Europe. This paper will explore recent research by several groups published in the review by Grünwald et al. (Grünwald, N.J.; Garbelotto, M.; Goss, E.M.; Heungens, K.; Prospero, S. 2012. Emergence of...

  1. Draft genome sequences of Phytophthora kernoviae and Phytophthora ramorum lineage EU2 from Scotland.

    PubMed

    Sambles, Christine; Schlenzig, Alexandra; O'Neill, Paul; Grant, Murray; Studholme, David J

    2015-12-01

    Newly discovered Phytophthora species include invasive pathogens that threaten trees and shrubs. We present draft genome assemblies for three isolates of Phytophthora kernoviae and one isolate of the EU2 lineage of Phytophthora ramorum, collected from outbreak sites in Scotland.

  2. Stream baiting in southern Louisiana for Phytophthora ramorum

    Treesearch

    Jason Preuette; Daniel Collins; Ashley Williams; Kenneth Deahl; Richard Jones

    2013-01-01

    The use of stream monitoring is an important method for early detection of Phytophthora ramorum. Five different waterway locations representing different ecosystems and potential P. ramorum inoculum sources across southern Louisiana were monitored for P. ramorum using bait bags containing whole ...

  3. Emergence of the sudden oak death pathogen Phytophthora ramorum

    Treesearch

    Niklaus J. Grunwald; Matteo Garbelotto; Erica M. Goss; Kurt Huengens; Simone Prospero

    2012-01-01

    The recently emerged plant pathogen Phytophthora ramorum is responsible for causing the sudden oak death epidemic. This review documents the emergence of P. ramorum based on evolutionary and population genetic analyses. Currently infection by P. ramorum occurs only in Europe and North America and three...

  4. Genome sequence of Phytophthora ramorum: implications for management

    Treesearch

    Brett Tyler; Sucheta Tripathy; Nik Grunwald; Kurt Lamour; Kelly Ivors; Matteo Garbelotto; Daniel Rokhsar; Nik Putnam; Igor Grigoriev; Jeffrey Boore

    2006-01-01

    A draft genome sequence has been determined for Phytophthora ramorum, together with a draft sequence of the soybean pathogen Phytophthora sojae. The P. ramorum genome was sequenced to a depth of 7-fold coverage, while the P. sojae genome was sequenced to a depth of 9-fold coverage. The genome...

  5. Root sssociations of Phytophthora ramorum and Phytophthora kernoviae in U.K. woodlands

    Treesearch

    Elizabeth Fichtner; David Rizzo; Susan Kirk; A. Whybrow; J. Webber.

    2009-01-01

    Phytophthora kernoviae and Phytophthora ramorum, two pathogens recently introduced to the U.K., incite foliar lesions, shoot necrosis, and death of Rhododendron ponticum, an invasive weed pervading U.K. woodlands. In infested woodlands, R. ponticum serves as an...

  6. Comparative host range and aggressiveness of Phytophthora ramorum and Phytophthora kernoviae sp. nov. on North American and European trees

    Treesearch

    Clive Brasier; Joan Rose; Susan Kirk; Sandra Denman; Joan Webber

    2006-01-01

    Phytophthora ramorum and P. kernoviae are recently introduced, invasive pathogens in woodlands in southern Britain. P. kernoviae, previously known as Phytophthora taxon C, is a newly discovered taxon, (Brasier and others 2005), found during surveys for P. ramorum in Cornwall...

  7. Status of Phytophthora ramorum and P. kernoviae in Europe

    Treesearch

    Joan F. Webber

    2008-01-01

    Following the recognition that Phytophthora ramorum (the cause of sudden oak death in the U.S.) was present in Europe as well as America, emergency European Community (EC) phytosanitary measures were put in place in September 2002 to prevent spread of P. ramorum, and also to stop introductions of the pathogen from elsewhere. A 3...

  8. Susceptibility of selected ornamental plants to Phytophthora ramorum

    Treesearch

    K. Kaminski; S. Wagner; S. Werres

    2008-01-01

    Within the European project ?Risk Analysis for Phytophthora ramorum? (RAPRA), susceptibility of economically and ecologically important plants in Europe towards P. ramorum was tested via in vitro inoculation methods. In these studies different species and/or cultivars of Buxus, Calluna...

  9. Genetic transformation of Phytophthora ramorum with the jellyfish GFP gene

    Treesearch

    G. Calmin; M. Riedel; L. Belbahri; S. Wagner; S. Werres; F. Lefort

    2009-01-01

    The important quarantine organism Phytophthora ramorum has been dramatically increasing its host range in the past years and most of the studies concerning P. ramorum focus on these issues. Very little is known about the latency period. For sampling and analyzing potentially infected plant material,...

  10. Can Phytophthora ramorum be spread with contaminated irrigation water?

    Treesearch

    D. Seipp; T. Brand; K. Kaminski; S. Wagner; S. Werres

    2008-01-01

    In a two year study, the spread of Phytophthora ramorum with contaminated irrigation water and the survival of the pathogen in water reservoirs were studied (Werres and others 2007). In addition at the end of each experimental period root ball samples from asymptomatic plants were taken to look for contamination with P. ramorum....

  11. Evaluation of fungicides for control of Phytophthora ramorum

    Treesearch

    S. Wagner; K. Kaminski; S. Werres

    2008-01-01

    As part of the project European Phytophthora ramorum Pest Risk Analysis (RAPRA) a wide range of fungicides was tested for in vitro activity against mycelial growth and zoospore germination of P. ramorum. A preliminary set of experiments was performed to study the effect of nine common fungicides specific for

  12. Studies of tissue colonization in Rhododendron by Phytophthora ramorum

    Treesearch

    Marko Riedel; Stefan Wagner; Monika Götz; Lassaad Belbahri; Francois Lefort; Sabine Werres

    2008-01-01

    The knowledge on latency is of great importance to prevent the spread of Phytophthora ramorum with healthy looking plant material. To learn more about the tissue colonisation in Rhododendron, histological studies with epifluorescence microscopy have been started. Epifluorescence images showing P. ramorum structures in different...

  13. Recovery of Phytophthora ramorum in plant tissue with mixed infections

    USDA-ARS?s Scientific Manuscript database

    This study was performed to investigate the frequency with which P. ramorum would be isolated from host tissue co-infected with P. ramorum as well as an indigenous Phytophthora species or P. kernoviae. Three separate experiments were tested in a similar manner using different combinations of pathog...

  14. First report of Phytophthora ramorum infecting mistletoe in California

    Treesearch

    K.L. Riley; G.A. Chastagner

    2011-01-01

    In 2005 and 2006, white fir and Douglas-fir growing in a Christmas tree plantation near Los Gatos, CA, under a black walnut tree infected with mistletoe tested positive for Phytophthora ramorum, the cause of Sudden Oak Death. Isolation from a symptomatic mistletoe inflorescence stalk was positive for P. ramorum. In 2007,...

  15. The current situation with Phytophthora ramorum in England and Wales

    Treesearch

    David Slawson; Lynne Bennett; Nicola Parry; Charles Lane

    2006-01-01

    Since the first finding of Phytophthora ramorum in England in April 2002, an intensive campaign, supported by the European Community (EC) and national legislation, has been conducted to locate and eradicate all interceptions and outbreaks of P. ramorum. A summary of the findings made during these surveys is presented, along with an...

  16. Factors Affecting Onset of Sporulation in Phytophthora ramorum

    USDA-ARS?s Scientific Manuscript database

    To elucidate the sporulation potential of the sudden oak death pathogen, Phytophthora ramorum, on rhododendron, we conducted a series of experiments looking at the relationship between moisture period, lesion size, and onset of sporangia production. Inoculations were performed using P. ramorum isol...

  17. Emergence of the sudden oak death pathogen Phytophthora ramorum

    USDA-ARS?s Scientific Manuscript database

    Phytophthora ramorum, the pathogen responsible for massive sudden oak death of tanoak, coast live oak and Japanese larch in the United States and the United Kingdom, is the latest example of an emerging pathogen. This review documents the emergence of P. ramorum based on detailed, recent evolutionar...

  18. Susceptibility of conifer shoots to infection by Phytophthora ramorum

    Treesearch

    G.A. Chastagner; E.M. Hansen; K.L. Riley; W. Sutton

    2006-01-01

    Phytophthora ramorum is the pathogen that causes sudden oak death, which was first detected on tanoak in Marin County, California in 1995. The identification of several conifers as hosts of P. ramorum and the increased spread of this pathogen via shipment of ornamental nursery stock has the potential to severely impact the...

  19. Screening Gulf Coast forest species for susceptibility to Phytophthora ramorum

    Treesearch

    Jason Preuett; Daniel Collins; Douglas Luster; Timothy Widmer

    2013-01-01

    Phytophthora ramorum, the causal agent of sudden oak death in California oak woodlands, poses a threat to woody plants in the rest of the United States, including the Gulf Coast area, which is regarded as a high-risk location. Several plant species native to Gulf Coast forests were tested for susceptibility to P. ramorum,...

  20. Thwarting Phytophthora ramorum: a proposed disease cycle with mitigation measures

    Treesearch

    Betsy Randall-Schadel; Scott Redlin

    2006-01-01

    Phytophthora ramorum has become increasingly disruptive to the movement of nursery stock since it was described in 2001. Risk and mitigation assessments for P. ramorum have been done or are underway by APHIS. Because of the impact of this pathogen on forests and the nursery industry, accelerated research efforts are underway....

  1. First report of Phytophthora ramorum infecting grand fir in California

    Treesearch

    K.L. Riley; G.A. Chastagner

    2011-01-01

    Phytophthora ramorum was detected on grand fir in 2003 and 2005 in a Christmas tree plantation near Los Gatos, CA, in association with infected California bay laurel. Isolates derived from stem lesions were used to inoculate grand fir seedlings in two tests. Isolations from lesions on inoculated plants were positive for P. ramorum...

  2. The maturation and germination of Phytophthora ramorum Chlamydospores

    Treesearch

    Aaron L. Smith; Everett M. Hansen

    2008-01-01

    Chlamydospores are a distinctive feature of Phytophthora ramorum. They are formed quickly in agar, and within colonized leaves. We followed their development and maturation in vitro and in vivo, and studied conditions affecting their germination. Cell walls of mature P. ramorum chlamydospores...

  3. An update on Phytophthora ramorum in European nurseries

    Treesearch

    David Slawson; Jennie Blackburn; Lynne Bennett

    2008-01-01

    Emergency phytosanitary measures to prevent the introduction into and spread within the European Union (EU) of Phytophthora ramorum Werres, De Cock & Man in 't Veld. have been in place since 2002. Surveillance across the EU, has confirmed the presence of P. ramorum on nurseries and retailers in 15 member states. ...

  4. Investigating the potential of biological control against Phytophthora ramorum

    Treesearch

    Timothy L. Widmer

    2008-01-01

    Phytophthora ramorum is a unique organism in many ways, having a broad host range and both soilborne and aerial infection stages. This makes mplementing effective control measures very complex. The use of biological control has been demonstrated against various Phytophthora spp. in general, but not specifically against P...

  5. Suppression of Phytophthora ramorum in aluminum-amended peatmoss

    Treesearch

    Elizabeth J. Fichtner; David M. Rizzo; David H. Shew

    2008-01-01

    Phytophthora ramorum, the pathogen responsible for sudden oak death, also impacts the ornamental nursery industry, enhancing the potential for long-distance pathogen transmission in asymptomatic roots or in infested potting media. Soil borne populations of another nursery pathogen, Phytophthora parasitica, are suppressed by...

  6. Draft genome sequences of Phytophthora kernoviae and Phytophthora ramorum lineage EU2 from Scotland

    PubMed Central

    Sambles, Christine; Schlenzig, Alexandra; O'Neill, Paul; Grant, Murray; Studholme, David J.

    2015-01-01

    Newly discovered Phytophthora species include invasive pathogens that threaten trees and shrubs. We present draft genome assemblies for three isolates of Phytophthora kernoviae and one isolate of the EU2 lineage of Phytophthora ramorum, collected from outbreak sites in Scotland. PMID:26697371

  7. Public value at risk from Phytophthora ramorum and Phytophthora kernoviae spread in England and Wales.

    PubMed

    Drake, Ben; Jones, Glyn

    2017-04-15

    Heritage gardens, heathland and woodland are increasingly under threat from the non-native tree and plant diseases Phytophthora ramorum and Phytophthora kernoviae. However, there exist only limited literature that estimates the public non-market value that may be lost from a continued spread of Phytophthora ramorum and Phytophthora kernoviae into these habitats. This paper therefore uses a contingent valuation survey to assess the non-extractive public use and non-use values at risk from an uncontrolled spread of these diseases in England and Wales. Results estimate that £1.446bn of public value is at risk in England and Wales per year from an uncontrolled spread of Phytophthora ramorum and Phytophthora kernoviae. The greatest public value at risk, of £578  m/year, is from an uncontrolled spread of these diseases to heritage gardens, while the lowest public value at risk, of £386  m/year, is from disease spread to heathland. The findings of this paper should help policymakers make informed decisions as to the public resources to dedicate towards Phytophthora ramorum and Phytophthora kernoviae control in England and Wales. In this regard, the current control programme to contain these diseases appears cost-effective in light of the public value at risk estimates produced by this paper. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Mitochondrial genomics in the Genus Phytophthora with a focus on Phytophthora ramorum

    Treesearch

    Frank N. Martin; Paul Richardson

    2008-01-01

    The mitochondrial genomes of Phytophthora infestans, P. ramorum and P. sojae have been sequenced and comparative genomics has provided an opportunity to examine the processes involved with genome evolution in the genus Phytophthora. This approach can also be useful in assessing intraspecific...

  9. The new Phytophthora ramorum dynamic in Europe: spread to larch

    Treesearch

    Anna Harris; Joan Webber

    2013-01-01

    Sudden oak death (SOD), caused by Phytophthora ramorum, is lethal to tanoak (Notholithocarpus densiflorus (Hook. & Arn.) Manos, Cannon & S.H. Oh), and threatens this species throughout its range in Oregon. The disease was first discovered in coastal southwest Oregon forests in July 2001. Since then an interagency team...

  10. An Overview of Phytophthora ramorum in Washington State

    Treesearch

    Gary A. Chastagner; Katie Coats; Marianne Elliott

    2013-01-01

    Sudden oak death (SOD), caused by Phytophthora ramorum, is lethal to tanoak (Notholithocarpus densiflorus (Hook. & Arn.) Manos, Cannon & S.H. Oh), and threatens this species throughout its range in Oregon. The disease was first discovered in coastal southwest Oregon forests in July 2001. Since then an interagency team...

  11. Susceptibility levels of Rhododendron species and hybrids to Phytophthora ramorum

    Treesearch

    Isabelle De Dobbelaere; Kurt Heungens; Martine Maes

    2006-01-01

    Until now there has been little scientific information available about the susceptibility of different Rhododendron species and cultivars to Phytophthora ramorum. However, growers could use this knowledge as part of their control strategy. In our susceptibility screening we first optimized different inoculation methods on stem and...

  12. Phytophthora ramorum causes cryptic bole cankers in Canyon line Oak

    USDA-ARS?s Scientific Manuscript database

    Unusual mortality of large canyon live oaks was observed in natural stands in San Mateo, California starting in 2007. A survey of affected stands showed that symptomatic trees were spatially associated with California bay, the primary source of Phytophthora ramorum spores in this forest type. Trunk ...

  13. Wildland management of Phytophthora ramorum in northern California forests

    Treesearch

    Yana Valachovic; Chris Lee; Jack Marshall; Hugh Scanlon

    2008-01-01

    In early 2006 we implemented a series of comparative silvicultural treatments aimed at managing the spread of Phytophthora ramorum Werres, de Cock & Man in?t Veld by reducing inoculum densities in isolated infestations on one public and three private properties in southern Humboldt County. These treatments, which took place on over 56 forested ha...

  14. Summer survival of Phytophthora ramorum in California bay laurel leaves

    Treesearch

    Elizabeth J. Fichtner; David M. Rizzo; Shannon C. Lynch; Jennifer Davidson; Gerri Buckles; Jennifer Parker

    2008-01-01

    Sudden oak death manifests as non-lethal foliar lesions on bay laurel (Umbellularia californica), which support sporulation and survival of Phytophthora ramorum in forest ecosystems. Infected bay laurel leaves are more likely to abscise than uninfected leaves, resulting in an accumulation of inoculum at the forest floor. The pathogen survives the dry...

  15. Phytophthora ramorum regulatory program: present, past, and future direction

    Treesearch

    Prakash Hebbar; Scott Pfister; Stacy Scott; Anthony Man-Son-Hing; Russ Bulluck

    2013-01-01

    Sudden oak death (SOD), caused by Phytophthora ramorum, is lethal to tanoak (Notholithocarpus densiflorus (Hook. & Arn.) Manos, Cannon & S.H. Oh), and threatens this species throughout its range in Oregon. The disease was first discovered in coastal southwest Oregon forests in July 2001. Since then an interagency team...

  16. EU2, a Fourth Evolutionary Lineage of Phytophthora ramorum

    Treesearch

    Kris Van Poucke; Selma Franceschini; Joan Webber; Kurt Heungens; Clive Brasier

    2013-01-01

    Sudden oak death (SOD), caused by Phytophthora ramorum, is lethal to tanoak (Notholithocarpus densiflorus (Hook. & Arn.) Manos, Cannon & S.H. Oh), and threatens this species throughout its range in Oregon. The disease was first discovered in coastal southwest Oregon forests in July 2001. Since then an interagency team...

  17. Consequences of Phytophthora ramorum infection in coast live oaks

    Treesearch

    Brice McPherson; David L. Wood; Sylvia R. Mori; Pavel Svihra; Richard B. Standiford; N. Maggi. Kelly

    2008-01-01

    Sudden oak death, caused by Phytophthora ramorum, has infected and killed large numbers of oaks (Quercus spp.) and tanoaks (Lithocarpus densiflorus) in California since the mid 1990s. Since March 2000 we have been investigating the interactions between patterns of disease progression and...

  18. Phytophthora ramorum and P. kernoviae: regulation in the European union

    Treesearch

    Stephen Hunter

    2008-01-01

    The history of the regulation of action against Phytophthora ramorum and P. kernoviae in the EU and U.K. is briefly summarised. For the former there are EU controls on the import of host plants, and the internal regime of plant passporting has been extended to cover Rhododendron, Viburnum and...

  19. Susceptibility of sprouted oak acorns to Phytophthora ramorum zoospores

    USDA-ARS?s Scientific Manuscript database

    Phytophthora ramorum is a recently emerged pathogen, having established in Europe and several western U.S. states, including California and Oregon. It has a wide host range and is a threat to forest ecology and the nursery industry. In California, coast live oak (Quercus agrifolia) is a major host...

  20. Monitoring Phytophthora ramorum distribution in streams within California watersheds

    Treesearch

    S.K. Murphy; C. Lee; Y. Valachovic; J. Bienapfl; W. Mark; A. Jirka; D.R. Owen; T.F. Smith; D.M. Rizzo

    2008-01-01

    One hundred-thirteen sites were established in perennial watercourses and sampled for 1 to 3 years between 2004 and 2006 to monitor for presence of Phytophthora ramorum throughout coastal central and northern California watersheds as well as portions of the Sierra Nevada mountain range (Murphy and others 2006). The majority of the monitored...

  1. Survival of Phytophthora ramorum chlamydospores at high and low temperatures

    USDA-ARS?s Scientific Manuscript database

    Phytophthora ramorum causes Sudden Oak Death, a destructive disease that imacts forest species, as well as, nursery crops in the U.S. and elsewhere. Chlamydospores were produced as described by Colburn and Shishkoff (Phytopathology 96:S25). Samples (5cc) of chlamydospores in sand inoculum were pl...

  2. Correlating Phytophthora ramorum infection rate and lesion expansion in tanoak

    Treesearch

    Katherine Hayden; Heather Rickard; Matteo Garbelotto

    2008-01-01

    To date, resistance to Phytophthora ramorum in its most susceptible hosts has most commonly been quantified by lesion growth, after wounding or non-wounding inoculations via mycelia or high concentrations of zoospores. However, even highly susceptible hosts may not always become infected when they are exposed to a pathogen under ecologically...

  3. Phenotypic variation among Phytophthora ramorum isolates from California and Oregon

    Treesearch

    Daniel Hüberli; Tamar Harnik; Matthew Meshriy; Lori Miles; Matteo Garbelotto

    2006-01-01

    To manage and control Phytophthora ramorum successfully, it is important to know the amount of phenotypic variation within a given pathogen population. Because the pathogen has only recently been described, there are few studies on morphological and pathological variation of isolates from the United States. One study has compared growth rate on agar...

  4. Histology of Phytophthora ramorum in Notholithocarpus densiflorus bark tissues

    Treesearch

    Molly Botts Giesbrecht; Everett M. Hansen; Peter Kitin

    2011-01-01

    Colonisation of Notholithocarpus densiflorus (Hook. and Arn.) Rehder tissues by Phytophthora ramorum Werres, De Cock & Man in't Veld is not well understood. The pathogen is able to colonise nearly all tissues of this host but it is unclear how a tree is ultimately killed. In this research,

  5. Chemistry of coast live oak response to Phytophthora ramorum infection

    Treesearch

    Frances S. Ockels; Alieta Eyles; Brice A. McPherson; David L. Wood; Pierluigi Bonello

    2008-01-01

    Since the mid 1990s, Phytophthora ramorum has been responsible for the widespread mortality of tanoaks, as well as several oak species throughout California and Oregon forests. However, not all trees die, even in areas with high disease pressure, suggesting that some trees may be resistant to the pathogen. The apparent resistance to P....

  6. The effects of salinity on Phytophthora ramorum viability and infectivity

    Treesearch

    Jason Preuette; Daniel Collins; Douglas Luster; Timothy Widmer

    2013-01-01

    Phytophthora ramorum, a threat to eastern United States forests, has been found in waterways outside the boundaries of infested ornamental nurseries in states other than California and Oregon. Very little is known about what factors are conducive to its survival and sporulation in water. Water collected from various sources with different salinity...

  7. Susceptibility of Australian plant species to Phytophthora ramorum

    Treesearch

    Kylie Ireland; Daniel H& uuml; berli; Bernard Dell; Ian Smith; David Rizzo; Giles. Hardy

    2010-01-01

    Phytophthora ramorum is an invasive plant pathogen causing considerable and widespread damage in nurseries, gardens, and natural woodland ecosystems of the United States and Europe, and is classified as a Category 1 pest in Australia. It is of particular interest to Australian plant biosecurity as, like P. cinnamomi; it has...

  8. Gene expression in the tanoak-Phytophthora ramorum interaction

    Treesearch

    Katherine J. Hayden; Matteo Garbelotto; Hardeep Fai; Brian Knaus; Richard Cronn; Jessica W. Wright

    2012-01-01

    Disease processes are dynamic, involving a suite of gene expression changes in both the host and the pathogen, all within a single tissue. As such, they lend themselves well to transcriptomic analysis. Here we focus on a generalist invasive pathogen (Phytophthora ramorum) and its most susceptible California Floristic Province native host, tanoak (...

  9. Phytophthora ramorum in Scotland: is it all over?

    Treesearch

    Alexandra Schlenzig

    2008-01-01

    Phytophthora ramorum was found for the first time in Scotland in April 2002 on some Viburnum tinus plants in a nursery. Seventeen more outbreaks were confirmed in the same year, all on plants moving in horticultural trade. Phytosanitary emergency measures to eradicate the disease were taken, such as destruction of infected plants...

  10. Epidemiology of Phytophthora ramorum infecting rhododendrons under simulated nursery conditions

    Treesearch

    S.A. Tjosvold; D.L. Chambers; S. Koike; E. Fichtner

    2006-01-01

    The current understanding of diseases caused by Phytophthora ramorum and their dynamics in nursery crops is almost entirely derived from casual field observations. The objectives of the study are to help understand basic biological factors such as, inoculum viability, dispersal, and infectivity that influence disease occurrence and severity in a...

  11. Detection, diversity, and population dynamics of waterborne Phytophthora ramorum populations

    Treesearch

    Catherine Eyre; Matteo Garbelotto

    2015-01-01

    Sudden oak death, the tree disease caused by Phytophthora ramorum, has significant environmental and economic impacts on natural forests on the U.S. west coast, plantations in the United Kingdom, and in the worldwide nursery trade. Stream baiting is vital for monitoring and early detection of the pathogen in high-risk areas and is performed...

  12. Pathways of infection for Phytophthora ramorum in rhododendron

    Treesearch

    Carrie D. Lewis; Jennifer L. Parke

    2006-01-01

    The lack of knowledge regarding infection biology of Phytophthora ramorum limits our understanding of its ecology and epidemiology. Pathways of infection in Rhododendron 'Nova Zembla' were investigated using tissue culture plantlets and 3-year-old container plants inoculated with zoospore suspensions (6 x 104 zoospores mL-1...

  13. Can Epiphytes reduce disease symptoms caused by Phytophthora ramorum

    USDA-ARS?s Scientific Manuscript database

    Leaf infection of ornamental species by Phytophthora ramorum has a significant impact on the spread of this disease. Fungicides have had limited effects on controlling this disease. With increasing concerns that repeated fungicide applications will exasperate the potential for fungicide resistance...

  14. Phenotypic differences among three clonal lineages of Phytophthora ramorum

    USDA-ARS?s Scientific Manuscript database

    There are three major clonal lineages of Phytophthora ramorum present in North America and Europe named NA1, NA2, and EU1. Twenty-three isolates representing all three lineages were evaluated for phenotype including (i) aggressiveness on detached Rhododendron leaves and (ii) growth rate at minimum, ...

  15. Log susceptibility of Iberian tree species to Phytophthora ramorum

    Treesearch

    Eduardo Moralejo; Enrique Descals; José Andrés García-Muñoz

    2008-01-01

    Phytophthora ramorum is a plant pathogen introduced into Europe and North America. It can infect any host species belonging to different botanical families within the seed plants. Such infective capacity indicates that it can overcome basic plant defence responses that have been phylogenetically conserved in plants (Heath 1991). In addition,

  16. Phytophthora ramorum detection surveys for forests in the United States

    Treesearch

    S. W. Oak; W. D. Smith; B.M. Tkacz

    2006-01-01

    Diseases caused by Phytophthora ramorum in forest landscapes of North America are presently confined to areas of the Pacific coast in the states of CA and OR. However, the vulnerability of other ecosystems is suggested by the discovery in Europe and the U.K. of disease in hosts which are abundant in oak-dominated ecosystems of eastern North America;...

  17. Monitoring Phytophthora ramorum distribution in streams within coastal California watersheds

    Treesearch

    S. Murphy; C. Lee; Y. Valachovic; A. Jirka; D.R. Owen; D. Rizzo; W. Mark

    2009-01-01

    One hundred eighty-seven sites were established in perennial watercourses and sampled for one to four years between 2004 and 2007 to monitor for the presence of Phytophthora ramorum throughout coastal central and northern California watersheds as well as portions of the Sierra Nevada mountain range. In 2007, 132 sites...

  18. Review of Phytophthora ramorum in European and North American nurseries

    Treesearch

    Janice Alexander

    2006-01-01

    In 2000, a previously unidentified Phytophthora isolated from rhododendrons in European nurseries and gardens was determined to be the same species – but a different population and mating type – as the pathogen causing sudden oak death in California. Upon recognizing the threats that P. ramorum posed to both wildlands and the...

  19. Phytophthora ramorum experience and approach in the Netherlands

    Treesearch

    M.H.C.G. Steeghs; J. De Gruyter

    2006-01-01

    Phytophthora ramorum was found for the first time in the Netherlands in 1993. In 2001 a risk analysis was done. The results initiated a program to investigate the spread in the Netherlands and to develop measures to prevent further spread. The measures outside the nurseries gave rise to intensive discussions with the managers and owners of these...

  20. Persistence of Phytophthora ramorum and Phytophthora kernoviae in U.K. natural areas and implications for North American forests

    Treesearch

    Elizabeth J. Fichtner; David M. Rizzo; Joan Kirk Webber; Alistair. Whybrow

    2010-01-01

    Phytophthora kernoviae (Pk) and Phytophthora ramorum (Pr) are recently introduced pathogens in United Kingdom (U.K.) woodlands. Pk is also an emerging threat to coastal heathland where it infects Vaccinium myrtillus. In infested woodlands,...

  1. Infection of tree stems by zoospores of Phytophthora ramorum and P. kernoviae

    Treesearch

    Clive Brasier; Anna Brown

    2008-01-01

    The invasive Phytophthora ramorum, P. kernoviae, and other aerial Phytophthoras are causing bleeding lesions on the trunks of mature trees, especially beech (Fagus sylvatica), in Cornwall, southwest England. The relationship between the results of host susceptibility tests using wound...

  2. Identification of five new hosts of Phytophthora ramorum in an infested forest in California

    Treesearch

    S. Rooney-Latham; C.L. Blomquist; A. Williams; E. Gunnison; T. Pastalka

    2017-01-01

    Phytophthora ramorum causes stem and bole cankers (sudden oak death) and foliar and twig dieback (ramorum blight) of susceptible plants. To date, more than 100 tree, shrub and herbaceous hosts of P. ramorum have been identified. In March 2015, plant samples were submitted to the CDFA Plant Pest Diagnostics...

  3. Standardizing the nomenclature for clonal lineages of the sudden oak death pathogen, Phytophthora ramorum

    Treesearch

    N.J. Grünwald; E.M. Goss; K. Ivors; M. Garbelotto; F.N. Martin; S. Prospero; E. Hansen; P.J.M. Bonants; R.C. Hamelin; G. Chastagner; S. Werres; D.M. Rizzo; G. Abad; P. Beales; G.J. Bilodeau; C.L. Blomquist; C. Brasier; S.C. Brière; A. Chandelier; J.M. Davidson; S. Denman; M. Elliott; S.J. Frankel; E.M. Goheen; H. de Gruyter; K. Heungens; D. James; A. Kanaskie; M.G. McWilliams; W. Man in ' t Veld; E. Moralejo; N.K. Osterbauer; M.E. Palm; J.L. Parke; A.M. Perez Sierra; S.F. Shamoun; N. Shishkoff; P.W. Tooley; A.M. Vettraino; J. Webber; T.L. Widmer

    2009-01-01

    Phytophthora ramorum, the causal agent of sudden oak death and ramorum blight, is known to exist as three distinct clonal lineages which can only be distinguished by performing molecular marker-based analyses. However, in the recent literature there exists no consensus on naming of these lineages. Here we propose a system for naming clonal lineages of P. ramorum based...

  4. Soil treatments for the potential elimination of Phytophthora ramorum in ornamental nursery beds

    Treesearch

    L. E. Yakabe; J. D. MacDonald

    2010-01-01

    Ramorum leaf blight, caused by Phytophthora ramorum, has reemerged at several California nurseries after removal of infested material. In many cases, reemergence was not associated with reintroduction of the pathogen and may be attributed to inoculum surviving in soil beds because P. ramorum propagules can survive for over a...

  5. Phytophthora ramorum detections in Canada: Evidence for migration within North America and from Europe

    Treesearch

    E.M. Goss; M. Larsen; A. Vercauteren; S. Werres; K. Heungens; N.J. Grünwald

    2011-01-01

    Phytophthora ramorum, the cause of sudden oak death on oak and ramorum blight on woody ornamentals, has been reported in ornamental nurseries on the West Coast of North America from British Columbia to California. Long-distance migration of P. ramorum has occurred via the nursery trade, and shipments of host plants are known to...

  6. Phytophthora ramorum: update On the impact and wider consequences of the epidemic in Britain

    Treesearch

    J.F. Webber

    2017-01-01

    Many new Phytophthora pathogens have arrived in the UK via the plant trade in recent decades, but arguably Phytophthora ramorum has been one of the most significant introductions to affect trees. From 2002 onwards during the early stages of the epidemic, the first impacts of P. ramorum were seen in...

  7. 2006 pilot survey for Phytophthora ramorum in forest streams in the USA

    Treesearch

    S.W. Oak; J. Hwang; S.N. Jeffers; B.M. Tkacz

    2008-01-01

    Methods for detecting Phytophthora ramorum and other Phytophthora species with rhododendron leaf baits were pilot tested in high-risk watersheds in 11 states for the purpose of recommending a national survey protocol. Ninety streams, including 14 draining P. ramorum.-endemic areas, yielded 587 baiting chances....

  8. Contingency planning for Phytophthora ramorum outbreaks: progress report work package 7, EU RAPRA project

    Treesearch

    M.H.C.G. Steeghs

    2008-01-01

    As part of the EU project ?Risk analysis for Phytophthora ramorum, a recently recognised pathogen threat to Europe and the cause of Sudden Oak Death in the USA? (acronym RAPRA) outbreak scenarios are defined and existing strategies for eradication and containment of Phytophthora ramorum evaluated. Based on the current knowledge...

  9. Production of gametangia by Phytophthora ramorum in vitro.

    PubMed

    Brasier, Clive; Kirk, Susan

    2004-07-01

    Until now gametangia have not been obtained between paired European A1 and American A2 isolates of Phytopthora ramorum in vitro. Their production in artificial culture relies on interspecific pairings. Using P. drechsleri and P. cambivora testers, 51 of 110 P. ramorum isolates from across Europe were all shown to be A1s; while 32 of 38 American isolates from across California and southwest Oregon were shown to be A2s. However, these interspecific pairings are complex, unusually slow and unpredictable. A range of culture media and conditions are described that were tested, unsuccessfully, with a view to enhancing the efficiency of the interspecific pairings. In further tests, gametangia were obtained between A1 and A2 isolates of P. ramorum when juvenile, pre-chlamydospore producing mycelia were mixed together on carrot agar. The gametangia formed in 3-10 d, sparsely to frequently, initially only within the boundaries of the mixed inocula but subsequently in the extended mycelial growth. Chlamydospores were also produced. This inoculum-mixing method, though again sometimes unpredictable, should enhance efficiency of testing for compatibility types and facilitate further studies on whether the sexual outcrossing system of P. ramorum is functional. Differences between sexual reproduction of P. ramorum and that of other heterothallic Phytophthora species are discussed.

  10. Phytophthora ramorum and Phytophthora kernoviae in England and Wales—Public Consultation and New Programme

    Treesearch

    Keith Walters; Claire Sansford; David. Slawson

    2010-01-01

    Since the first reports in Great Britain (GB) of Phytophthora ramorum (2002) and P. kernoviae (2003), the death of a small number of infected trees and of heathland Vaccinium has been recorded. Initial policy against these pathogens was one of containment, with a view to eradication...

  11. Phytophthora ramorum + P. kernoviae = international biosecurity failure

    Treesearch

    Clive Brasier

    2008-01-01

    For a scientist, my title may seem a little sensationalist in tone. This is deliberate - to draw attention to my issue. And here?s the issue. About six years ago the previously unknown invasive pathogen P. ramorum sp. nov. was found spreading on trees and shrubs in North America and Europe. Almost simultaneously in the U.K. we found another...

  12. Epidemiology of Phytophthora ramorum in Oregon

    Treesearch

    E.M. Hansen; A. Kanaskie; E.M. Goheen; N. Osterbauer; W. Sutton

    2006-01-01

    We are studying how P. ramorum survives and spreads in Oregon tanoak forests. The Oregon outbreak is similar to the epidemic in redwood-tanoak forests of California, with several important differences, however. The disease is confined to scattered stands within a 12 m2 area, and it is subject to an ongoing eradication effort....

  13. Molecular markers for identification of P. ramorum and other Phytophthora species from diseased tissue

    Treesearch

    Frank N. Martin; Paul W. Tooley

    2006-01-01

    Molecular techniques have been developed for detection and identification of P. ramorum and other Phytophthora species that are based on the mitochondrially encoded sequences. One technique uses a Phytophthora genus specific primer to determine if a Phytophthora species is present, followed by...

  14. Variation in phenotype for resistance to Phytophthora ramorum in a range of species and cultivars of the genus Viburnum

    Treesearch

    Niklaus J. Grunwald; E. Anne Davis; Robert G. Linderman

    2006-01-01

    Phytophthora ramorum is a recently introduced plant pathogen causing a range of diseases including sudden oak death, Ramorum shoot dieback and Ramorum blight (Rizzo and others 2002, 2004; Werres and others 2001). P. ramorum also attacks several nursery crops including viburnum and rhododendron (Werres and others 2001). Since its...

  15. ELISA and ImmunoStrip® for detection of Phytophthora ramorum, P. kernoviae, and other Phytophthora species

    Treesearch

    Francisco J. Avila; Barbara Schoedel; Z. Gloria Abad; Michael D. Coffey; Cheryl Blomquist

    2009-01-01

    The goal of this work was to develop improved tools for the detection of Phytophthora ramorum and P. kernoviae for field and the laboratory use. ImmunoStrip® and ELISA were selected as the test formats for development. Presently, the diagnosis of sudden oak death (SOD) in the national survey of P. ramorum ...

  16. Phytophthora ramorum in Oregon forests: six years of detection, eradication, and disease spread

    Treesearch

    Alan Kanaskie; Everett Hansen; Ellen Goheen; Michael McWilliams; Paul Reeser; Wendy Sutton

    2009-01-01

    Phytophthora ramorum was first discovered in Southwest Oregon forests in 2001, where it was killing tanoak (Lithocarpus densiflorus) and infecting Pacific rhododendron (Rhododendron macrophyllum) and evergreen huckleberry (Vaccinium ovatum). At that time there were nine infested forest...

  17. A test system to quantify inoculum in runoff from Phytophthora ramorum-infected plant roots

    Treesearch

    Nina. Shishkoff

    2010-01-01

    Foliar hosts of Phytophthora ramorum are often susceptible to root infection, but the epidemiological significance of such infections is unknown. We used a standardized test system to study inoculum in runoff from root-infected Viburnum tinus cuttings.

  18. Persistence of Phytophthora ramorum after eradication treatments in Oregon tanoak forests

    Treesearch

    Ellen Goheen; Everett Hansen; Alan Kanaskie; Wendy Sutton; Paul Reeser

    2009-01-01

    Sudden oak death, caused by Phytophthora ramorum, was identified in late July 2001 in forest stands in Curry County on the Southwest Oregon coast where it was killing tanoak (Lithocarpus densiflorus) and infecting Pacific rhododendron (Rhododendron macrophyllum) and evergreen huckleberry (...

  19. Phytophthora ramorum and sudden oak death in California: I. host relationships

    Treesearch

    David M. Rizzo; Matteo Garbelotto; Jennifer M. Davidson; Garey M. Slaughter; Steven T. Koike

    2002-01-01

    A new canker disease of Lithocarpus densiflorus, Quercus agrifolia, Q. kellogii, and Q. parvula var. shrevei in California is shown to be caused by Phytophthora ramorum. The pathogen is a recently described species that was previously known only from...

  20. Monitoring for Phytophthora ramorum and other species of Phytophthora in nurseries and urban areas in the Southeastern USA

    Treesearch

    Yeshi A. Wamishe; Steven N. Jeffers; Jaesoon Hwang

    2008-01-01

    Nurseries in the southeastern United States that received ornamental plants in 2004 colonized by Phytophthora ramorum and the surrounding urban areas are being monitored to determine if this pathogen has escaped and become established. At the same time, the prevalence and diversity of other species of Phytophthora are being...

  1. Determining the risk of Phytophthora ramorum spread from nurseries via waterways

    Treesearch

    Marianne Elliott; Gary Chastagner; Katie Coats; Gil Dermott

    2013-01-01

    Phytophthora ramorum, the fungus-like pathogen which causes sudden oak death, is a threat to the Pacific Northwest nursery industry. Because this is a quarantine organism, the destruction of plants and mitigation treatments resulting from a positive P. ramorum detection has caused millions of dollars in losses to the commercial...

  2. Phytophthora ramorum and sudden oak death in California: III. preliminary studies in pathogen genetics

    Treesearch

    Matteo Garbelotto; David M. Rizzo; Katie Hayden; Monica Meija-Chang; Jennifer M. Davidson; Steven Tjosvold

    2002-01-01

    Sudden oak death (SOD) has been shown to be caused by a new species of Phytophthora, P. ramorum. A basic understanding of the genetics of P. ramorum is critical to any management strategy. We have initiated a number of studies to examine species concepts, population biology and mating behavior of the pathogen....

  3. Clonal Expansion of the Belgian Phytophthora ramorum Populations Based on New Microsatellite Markers

    USDA-ARS?s Scientific Manuscript database

    Coexistence of both mating types A1 and A2 within the EU1 lineage of Phytophthora ramorum has only been observed in Belgium, begging the question whether sexual reproduction is occurring. A collection of 411 Belgian P. ramorum isolates was established during a seven year survey. Our main objective w...

  4. Management of foliar infection of Rhododendron by Phytophthora ramorum with film forming polymers and surfactants

    Treesearch

    Ebba K. Peterson; Eric Larson

    2017-01-01

    Phytophthora ramorum, causal agent of sudden oak death (SOD) and ramorum leaf blight, remains a persistent problem of regulatory concern within the horticultural industry. Damages to nurseries have been realized as a result of enforced quarantine and sanitation efforts designed to prevent the spread and establishment of this invasive pathogen....

  5. Detection of Phytophthora ramorum at retail nurseries in the southeastern United States

    Treesearch

    Steven N. Jeffers; Jaesoon Hwang; Yeshi A. Wamishe; Steven W. Oak

    2010-01-01

    Many nursery plants are known to be hosts of Phytophthora ramorum or to be associated with this pathogen. These plants can be infected or merely infested by P. ramorum and with or without symptoms. The pathogen has been detected most frequently on container-grown nursery plants, and occasionally has been found in the container...

  6. Natural outbreaks of Phytophthora ramorum in the U.K.—current status and monitoring update

    Treesearch

    Judith Turner; Philip Jennings; Gilli Humphries; Steve Parker; Sam McDonough; Jackie Stonehouse; David Lockley; David Slawson

    2008-01-01

    To date (February 2007) there have been 160 outbreaks of Phytophthora ramorum in gardens or woodlands in the U.K. Current EU policy requires that appropriate measures be taken to contain P. ramorum in such situations. In the U.K., the measures have either been aimed at eradication, through destruction of infected plants, or at...

  7. Susceptibility of some common Eastern forest understory plant species to Phytophthora ramorum

    USDA-ARS?s Scientific Manuscript database

    We evaluated the susceptibility of 25 plant species (21 genera, 14 families), which comprise a portion of the understory in forests of the Eastern US, to infection by Phytophthora ramorum. We also assessed the degree to which P. ramorum is able to form sporangia and chlamydospores on these hosts. ...

  8. What can availability of the Phytophthora ramorum genome do for us?

    Treesearch

    Niklaus J. Grünwald

    2008-01-01

    The complete genomes of Phytophthora ramorum and P. sojae have recently been sequenced. Of the 19,027 predicted genes in P. sojae and 15,743 gene models in P. ramorum, 9,768 are predicted to have the same function. These two genomes both revealed a rapid expansion and diversification of many...

  9. The effect of Phytophthora ramorum on the physiology and xylem function of young tanoak trees

    Treesearch

    Elizabeth Stamm; Jennifer Parke

    2013-01-01

    Tanoak (Notholithocarpus densiflorus (Hook. & Arn.) Manos, C.H. Cannon & S. H. Oh) is highly susceptible to Phytophthora ramorum. Symptoms include stem cankers, shoot dieback, and foliar blight. The mechanism by which P. ramorum kills the trees is not known, however. In this study we aimed to...

  10. Recommended industry best management practices for the prevention of Phytophthora ramorum introduction in nursery operations

    Treesearch

    Karen Suslow

    2008-01-01

    The following industry recommended best management practices (BMPs), designed for growers and/or interstate shippers of host and associated host plants of Phytophthora ramorum, consists of biosecurity guidelines created by and for nursery growers in order to reduce the risks associated with P. ramorum. The control of P....

  11. Assessment of potential economic and environmental impacts caused by Phytophthora ramorum in Europe

    Treesearch

    Hella Kehlenbeck

    2008-01-01

    Economic and environmental impacts of Phytophthora ramorum in Europe were evaluated within the European Union framework 6 project on ?Risk Analysis for P. ramorum a pathogen threat to Europe? (RAPRA). Impact assessment was conducted according to three different scenarios: 1. ?Nursery System? - describes losses occurring in...

  12. Susceptibility to Phytophthora ramorum and inoculum production potential of some common eastern forest understory plant species

    Treesearch

    Paul W. Tooley; Marsha Browning

    2009-01-01

    Twenty-five plant species (21 genera, 14 families), which comprise a portion of the understory in forests of the Eastern United States, were evaluated for susceptibility to infection by Phytophthora ramorum. The degree to which P. ramorum is able to form sporangia and chlamydospores was also assessed on...

  13. Infection of five Phytophthora ramorum hosts in response to increasing inoculum levels

    Treesearch

    Paul Tooley; Marsha Browning; Robert Leighty

    2013-01-01

    The objective of this work was to establish inoculum density relationships between Phytophthora ramorum and selected hosts based on whole plant inoculations. Knowledge of levels of initial inoculum needed to generate epidemics is needed for disease prediction and development of pest risk assessments. Sporangia of six P. ramorum...

  14. Clonal expansion of the Belgian Phytophthora ramorum populations based on new microsatellite markers

    Treesearch

    A. Vercauteren; I. De Dobbelaere; N. J. Grünwald; P. Bonants; E. Van Bockstaele; M. Maes; K. Heungens

    2010-01-01

    Co-existence of both mating types A1 and A2 within the EU1 lineage of Phytophthora ramorum has only been observed in Belgium, which begs the question whether sexual reproduction is occurring. A collection of 411 Belgian P. ramorum isolates was established during a 7-year survey. Our main objectives were genetic characterization of this population to test for sexual...

  15. Development of reagents for immunoassay of Phytophthora ramorum in nursery water samples

    Treesearch

    Douglas G. Luster; Timothy Widmer; Michael McMahon; C. André Lévesque

    2017-01-01

    Current regulations under the August 6, 2014 USDA APHIS Official Regulatory Protocol (Confirmed Nursery Protocol: Version 8.2) for Nurseries Containing Plants Infected with Phytophthora ramorum mandates the sampling of water in affected nurseries to demonstrate they are free of P. ramorum. Currently, detection of

  16. Draft genome sequences of seven isolates of Phytophthora ramorum EU2 from Northern Ireland

    PubMed Central

    Mata Saez, Lourdes de la; McCracken, Alistair R.; Cooke, Louise R.; O'Neill, Paul; Grant, Murray; Studholme, David J.

    2015-01-01

    Here we present draft-quality genome sequence assemblies for the oomycete Phytophthora ramorum genetic lineage EU2. We sequenced genomes of seven isolates collected in Northern Ireland between 2010 and 2012. Multiple genome sequences from P. ramorum EU2 will be valuable for identifying genetic variation within the clonal lineage that can be useful for tracking its spread. PMID:26697370

  17. Draft genome sequences of seven isolates of Phytophthora ramorum EU2 from Northern Ireland.

    PubMed

    Mata Saez, Lourdes de la; McCracken, Alistair R; Cooke, Louise R; O'Neill, Paul; Grant, Murray; Studholme, David J

    2015-12-01

    Here we present draft-quality genome sequence assemblies for the oomycete Phytophthora ramorum genetic lineage EU2. We sequenced genomes of seven isolates collected in Northern Ireland between 2010 and 2012. Multiple genome sequences from P. ramorum EU2 will be valuable for identifying genetic variation within the clonal lineage that can be useful for tracking its spread.

  18. Climate-host mapping of Phytophthora ramorum, causal agent of sudden oak death

    Treesearch

    Glenn Fowler; Roger Magarey; Manuel Colunga

    2006-01-01

    Phytophthora ramorum infection was modeled using the NAPPFAST system for the conterminous United States. Parameters used to model P. ramorum infection were: leaf wetness, minimum temperature, optimum temperature and maximum temperature over a specified number of accumulated days. The model was used to create maps showing the...

  19. Interaction of Trichoderma asperellum with Phytophthora ramorum inoculum soil populations and enzyme secretion

    Treesearch

    Supriya Sharma; Wolfgang Schweigkofler; Karen Suslow; Timothy L. Widmer

    2017-01-01

    There is a continuing desire to investigate the potential of biological control to manage the spread of Phytophthora ramorum. A specific isolate of Trichoderma asperellum has been demonstrated to be effective in reducing P. ramorum soil populations to non-detectable levels. This study was conducted...

  20. Spread and development of Phytophthora ramorum in a California christmas tree farm

    Treesearch

    Gary A. Chastagner; Kathy Riley; Norm Dart

    2008-01-01

    The risk of conifers being infected by Phytophthora ramorum under natural conditions is poorly understood. In California, infected conifers commonly occur as understory plants beneath or adjacent to heavily infected plants like California bay laurel (Umbellularia californica). During wet periods, P. ramorum is...

  1. Use of microsatellite markers derived from whole genome sequence data for identifying polymorphism in Phytophthora ramorum

    Treesearch

    Kelly Ivors; Matteo Garbelotto; Ineke De Vries; Peter Bonants

    2006-01-01

    Investigating the population genetics of Phytophthora ramorum, the causal agent of sudden oak death (SOD), is critical to understanding the biology and epidemiology of this important phytopathogen. Raw sequence data (445,000 reads) of P. ramorum was provided by the Joint Genome Institute. Our objective was to develop and utilize...

  2. Susceptibility to Phytophthora ramorum in California bay laurel, a key foliar host of sudden oak death

    Treesearch

    Brian L. Anacker; Nathan E. Rank; Daniel Hüberli; Matteo Garbelotto; Sarah Gordon; Rich Whitkus; Tami Harnik; Matthew Meshriy; Lori Miles; Ross K. Meentemeyer

    2008-01-01

    Sudden oak death, caused by the water mold Phytophthora ramorum, is a plant disease responsible for the death of hundreds of thousands of oak and tanoak trees. Some foliar hosts play a major role in the epidemiology of this disease. Upon infection by P. ramorum, these foliar hosts express non-fatal leaf lesions from which large...

  3. Sudden oak death and Phytophthora ramorum: a summary of the literature

    Treesearch

    John T. Kliejunas

    2010-01-01

    Sudden oak death and Phytophthora ramorum, both first recognized about a decade ago, have been the subject of hundreds of scientific and popular press articles. This document presents a comprehensive, concise summary of sudden oak death and P. ramorum research findings and management activities. Topics covered include...

  4. Monitoring Phytophthora ramorum in soil, leaf litter, rain traps, and watercourses in an historical cornish garden

    Treesearch

    David Lockley; Judith Turner; Gillian Humphries; Phil Jennings

    2008-01-01

    Phytophthora ramorum was identified as the cause of a leaf blight on rhododendrons in an historic garden in Cornwall in 2003. A programme of measures was set in place to eradicate the disease from the garden and several sites were selected to monitor the effect of these measures on the recovery of P. ramorum from soil, leaf litter...

  5. Converting biology into regulations: U.S. Phytophthora ramorum quarantine as a case study

    Treesearch

    Susan J. Frankel; Steven W. Oak

    2006-01-01

    Regulation of Phytophthora ramorum, cause of sudden oak death and other diseases, has resulted in endless challenges for regulators, and the forest and nursery industries in the United States. This paper outlines the process used to design U.S. P. ramorum quarantines and explores some of the biological paradoxes presented by having...

  6. Standardizing the Nomenclature for Clonal Lineages of the Sudden Oak Death Pathogen, Phytophthora ramorum

    USDA-ARS?s Scientific Manuscript database

    Phytophthora ramorum, the causal agent of sudden oak death and ramorum blight, is known to exist as three distinct clonal lineages based on a range of molecular marker systems. However, in the recent literature there exists no consensus on naming of lineages. Here we name clonal lineages of P. ramor...

  7. Real-Time Fluorescent Polymerase Chain Reaction Detection of Phytophthora ramorum and Phytophthora pseudosyringae Using Mitochondrial Gene Regions.

    PubMed

    Tooley, Paul W; Martin, Frank N; Carras, Marie M; Frederick, Reid D

    2006-04-01

    ABSTRACT A real-time fluorescent polymerase chain reaction (PCR) detection method for the sudden oak death pathogen Phytophthora ramorum was developed based on mitochondrial DNA sequence with an ABI Prism 7700 (TaqMan) Sequence Detection System. Primers and probes were also developed for detecting P. pseudosyringae, a newly described species that causes symptoms similar to P. ramorum on certain hosts. The species-specific primer-probe systems were combined in a multiplex assay with a plant primer-probe system to allow plant DNA present in extracted samples to serve as a positive control in each reaction. The lower limit of detection of P. ramorum DNA was 1 fg of genomic DNA, lower than for many other described PCR procedures for detecting Phytophthora species. The assay was also used in a three-way multiplex format to simultaneously detect P. ramorum, P. pseudosyringae, and plant DNA in a single tube. P. ramorum was detected down to a 10(-5) dilution of extracted tissue of artificially infected rhododendron 'Cunningham's White', and the amount of pathogen DNA present in the infected tissue was estimated using a standard curve. The multiplex assay was also used to detect P. ramorum in infected California field samples from several hosts determined to contain the pathogen by other methods. The real-time PCR assay we describe is highly sensitive and specific, and has several advantages over conventional PCR assays used for P. ramorum detection to confirm positive P. ramorum finds in nurseries and elsewhere.

  8. Phytophthora ramorum and sudden oak death in California: IV. preliminary studies on chemical control

    Treesearch

    Matteo Garbelotto; David M. Rizzo; Lawrence Marais

    2002-01-01

    Chemical applications may provide one means of control for Phytophthora ramorum, the cause of Sudden Oak Death (SOD). Such controls have been effective with other Phytophthora species in landscape and orchard situations. We have initiated laboratory and field studies to test the efficacy of a number of products previously reported...

  9. Update on European Union and United Kingdom legislation for Phytophthora ramorum

    Treesearch

    Stephen Hunter

    2006-01-01

    Legislative action at both the European Union (E.U.) and United Kingdom (U.K.) national level has been taken in response to outbreaks of Phytophthora ramorum and, more recently, Phytophthora kernoviae. Measures are aimed at identifying and preventing the movement of infected nursery stock and the containment and eradication of...

  10. Distribution of Phytophthora ramorum, P. nemorosa, and P.pseudosyringae in native coastal California forest communities

    Treesearch

    S.K. Murphy; A.C. Wickland; S.C. Lynch; C.E. Jensen; P.E. Maloney; D.M. Rizzo

    2008-01-01

    Phytophthora ramorum, causal agent of sudden oak death, is well established over approximately 450 km of native forest along the California coast. In the course of research on this invasive exotic pathogen, two other putatively exotic aerial Phytophthora species, P. nemorosa and P. pseudosyringae...

  11. Invasion of xylem of mature tree stems by Phytophthora ramorum and P. kernoviae

    Treesearch

    Anna Brown; Clive Brasier

    2008-01-01

    The aetiology and frequency of Phytophthoras in discoloured xylem tissue beneath phloem lesions was investigated in a range of broadleaved trees infected with P. ramorum, P. kernoviae and several other Phytophthoras. Isolation was attempted from the inner surface of 81, 6 x 4 cm sterilised...

  12. Sporulation of Phytophthora ramorum and P. kernoviae on asymptomatic foliage and fruit

    Treesearch

    S. Denman; E. Moralejo; S.A. Kirk; E. Orton; A. Whybrow

    2008-01-01

    Phytophthora ramorum and P. kernoviae are newly discovered invasive Phytophthoras causing leaf necrosis, shoot tip dieback (mostly on ornamental and forest understorey host species) and bleeding cankers on tree trunks of a wide range of plant species. Both pathogens are now present in south-west England....

  13. What Can Availability of the Phytophthora ramorum Genome Do for Us?

    USDA-ARS?s Scientific Manuscript database

    The complete genomes of Phytophthora ramorum and P. sojae were sequenced in 2004. Two obvious questions arise, What contributions does the availability of a genome sequence make toward understanding the biology of Phytophthora spp.? What are the implications for management of sudden oak death in the...

  14. Incidence of Phytophthora ramorum, P. nemorosa and P. pseudosyringae in three coastal California forest communities

    Treesearch

    Shannon K. Murphy; David M. Rizzo

    2006-01-01

    Phytophthora ramorum is well established over approximately 450 km of forests along the California coast. In the course of research on this emerging pathogen, two other aerial species of Phytophthora, P. nemorosa and P. pseudosyringae, were discovered. Little is known about the ecology and...

  15. Antimicrobial activity of extractable conifer heartwood compounds toward Phytophthora ramorum.

    PubMed

    Manter, Daniel K; Kelsey, Rick G; Karchesy, Joseph J

    2007-11-01

    Ethyl acetate extracts from heartwood of seven western conifer trees and individual volatile compounds in the extracts were tested for antimicrobial activity against Phytophthora ramorum. Extracts from incense and western redcedar exhibited the strongest activity, followed by yellow-cedar, western juniper, and Port-Orford-cedar with moderate activity, and no activity for Douglas-fir and redwood extracts. Chemical composition of the extracts varied both qualitatively and quantitatively among the species with a total of 37 compounds identified by mass spectrometry. Of the 13 individual heartwood compounds bioassayed, three showed strong activity with a Log(10) EC(50) less than or equal to 1.0 ppm (hinokitiol, thymoquinone, and nootkatin), three expressed moderate activity ranging from 1.0-2.0 ppm (nootkatol, carvacrol, and valencene-11,12-diol), four compounds had weak activity at 2.0-3.0 ppm [alpha-terpineol, valencene-13-ol, (+)-beta-cedrene, (-)-thujopsene], and three had no activity [(+)-cedrol, delta-cadinene, and methyl carvacrol]. All of the most active compounds contained a free hydroxyl group, except thymoquinone. The importance of a free hydroxyl was demonstrated by the tremendous difference in activity between carvacrol (Log(10) EC(50) 1.81 +/- 0.08 ppm) and methyl carvacrol (Log(10) EC(50) >3.0 ppm). A field trial in California, showed that heartwood chips from redcedar placed on the forest floor for 4 months under Umbellularia californica (California bay laurel) with symptoms of P. ramorum leaf blight significantly limited the accumulation of P. ramorum DNA in the litter layer, compared with heartwood chips from redwood.

  16. Sources of inoculum for Phytophthora ramorum in a redwood forest.

    PubMed

    Davidson, J M; Patterson, H A; Rizzo, D M

    2008-08-01

    ABSTRACT Sources of inoculum were investigated for dominant hosts of Phytophthora ramorum in a redwood forest. Infected trunks, twigs, and/or leaves of bay laurel (Umbellularia californica), tanoak (Lithocarpus densiflorus), and redwood (Sequoia sempervirens) were tested in the laboratory for sporangia production. Sporangia occurred on all plant tissues with the highest percentage on bay laurel leaves and tanoak twigs. To further compare these two species, field measurements of inoculum production and infection were conducted during the rainy seasons of 2003-04 and 2004-05. Inoculum levels in throughfall rainwater and from individual infections were significantly higher for bay laurel as opposed to tanoak for both seasons. Both measurements of inoculum production from bay laurel were significantly greater during 2004-05 when rainfall extended longer into the spring, while inoculum quantities for tanoak were not significantly different between the 2 years. Tanoak twigs were more likely to be infected than bay laurel leaves in 2003-04, and equally likely to be infected in 2004-05. These results indicate that the majority of P. ramorum inoculum in redwood forest is produced from infections on bay laurel leaves. Years with extended rains pose an elevated risk for tanoak because inoculum levels are higher and infectious periods continue into late spring.

  17. Detection, Diversity, and Population Dynamics of Waterborne Phytophthora ramorum Populations.

    PubMed

    Eyre, C A; Garbelotto, M

    2015-01-01

    Sudden oak death, the tree disease caused by Phytophthora ramorum, has significant environmental and economic impacts on natural forests on the U.S. west coast, plantations in the United Kingdom, and in the worldwide nursery trade. Stream baiting is vital for monitoring and early detection of the pathogen in high-risk areas and is performed routinely; however, little is known about the nature of water-borne P. ramorum populations. Two drainages in an infested California forest were monitored intensively using stream-baiting for 2 years between 2009 and 2011. Pathogen presence was determined both by isolation and polymerase chain reaction (PCR) from symptomatic bait leaves. Isolates were analyzed using simple sequence repeats to study population dynamics and genetic structure through time. Isolation was successful primarily only during spring conditions, while PCR extended the period of pathogen detection to most of the year. Water populations were extremely diverse, and changed between seasons and years. A few abundant genotypes dominated the water during conditions considered optimal for aerial populations, and matched those dominant in aerial populations. Temporal patterns of genotypic diversification and evenness were identical among aerial, soil, and water populations, indicating that all three substrates are part of the same epidemiological cycle, strongly influenced by rainfall and sporulation on leaves. However, there was structuring between substrates, likely arising due to reduced selection pressure in the water. Additionally, water populations showed wholesale mixing of genotypes without the evident spatial autocorrelation present in leaf and soil populations.

  18. Soil treatments for the elimination of Phytophthora ramorum from nursery beds: current knowledge from the Laboratory and the field

    Treesearch

    L.E. Yakabe; J.D. MacDonald

    2008-01-01

    Over the past years, ramorum blight, caused by Phytophthora ramorum, has reoccurred at specific nurseries. In many cases, the re-emergence of the disease could not be traced to a second introduction. Since it is known that P. ramorum propagules can survive for over a year in soil, it is not unreasonable to hypothesize re-emergence...

  19. Development and validation of polymorphic microsatellite loci for the NA2 lineage of Phytophthora ramorum from whole genome sequence data

    USDA-ARS?s Scientific Manuscript database

    Phytophthora ramorum is the causal agent of sudden oak death and sudden larch death, and is also responsible for causing ramorum blight on woody ornamental plants. Many microsatellite markers are available to characterize the genetic diversity and population structure of P. ramorum. However, only tw...

  20. Migration patterns of the emerging plant pathogen Phytophthora ramorum on the West Coast of the United States of America

    Treesearch

    S. Prospero; N.J. Grünwald; L.M. Winton; E.M. Hansen

    2009-01-01

    Phytophthora ramorum (oomycetes) is the causal agent of sudden oak death and ramorum blight on trees, shrubs, and woody ornamentals in the forests of coastal California and southwestern Oregon and in nurseries of California, Oregon, and Washington. In this study, we investigated the genetic structure of P. ramorum on the West...

  1. Phenotypic diversification is associated with host-induced transposon derepression in the sudden oak death pathogen Phytophthora ramorum

    Treesearch

    T. Kasuga; M. Kozanitas; M. Bui; D. Huberli; D. M. Rizzo; M. Garbelotto

    2012-01-01

    The oomycete pathogen Phytophthora ramorum is responsible for sudden oak death (SOD) in California coastal forests. P. ramorum is a generalist pathogen with over 100 known host species. Three or four closely related genotypes of P. ramorum (from a single lineage) were...

  2. Monitoring Phytophthora ramorum and P. kernoviae in soil and rainwater samples collected at two sites on a cornish estate

    Treesearch

    David Lockley; Judith Turner; Gillian Humphries; Phil Jennings

    2008-01-01

    Soil samples were collected from quadrats marked out below the canopies of two rhododendrons, one infected by Phytophthora ramorum (Site 1) and the other (Site 2) infected by Phytophthora kernoviae and P. ramorum. Rainwater was collected in high-level and low level traps. Soil and rainwater were sampled at...

  3. Biological differences between the evolutionary lineages within Phytophthora ramorum and Phytophthora lateralis: Should the lineages be formally taxonomically designated?

    Treesearch

    Clive Brasier

    2017-01-01

    It is now generally accepted that the four evolutionary lineages of Phytophthora ramorum (informally designated NA1, NA2, EU1, and EU2) are relatively anciently divergent populations, recently introduced into Europe and North America from different, unknown geographic locations; that recombinants between them are genetically unstable and probably...

  4. Phytophthora ramorum and Phytophthora gonapodyides differently colonize and contribute to decay of California bay laurel (Umbellularia californica) leaf litter in stream ecosystems

    Treesearch

    Kamyar Aram; David M. Rizzo

    2017-01-01

    The prevalence of Phytophthora species in surface waters has earned increasing attention in the past decades, in great part as a result of “stream monitoring” programs for detection and monitoring of Phytophthora ramorum and other invasive species. The potential for Phytophthora ...

  5. Effect of plant sterols and tannins on Phytophthora ramorum growth and sporulation.

    PubMed

    Stong, Rachel A; Kolodny, Eli; Kelsey, Rick G; González-Hernández, M P; Vivanco, Jorge M; Manter, Daniel K

    2013-06-01

    Elicitin-mediated acquisition of plant sterols is required for growth and sporulation of Phytophthora spp. This study examined the interactions between elicitins, sterols, and tannins. Ground leaf tissue, sterols, and tannin-enriched extracts were obtained from three different plant species (California bay laurel, California black oak, and Oregon white oak) in order to evaluate the effect of differing sterol/tannin contents on Phytophthora ramorum growth. For all three species, high levels of foliage inhibited P. ramorum growth and sporulation, with a steeper concentration dependence for the two oak samples. Phytophthora ramorum growth and sporulation were inhibited by either phytosterols or tannin-enriched extracts. High levels of sterols diminished elicitin gene expression in P. ramorum; whereas the tannin-enriched extract decreased the amount of 'functional' or ELISA-detectable elicitin, but not gene expression. Across all treatment combinations, P. ramorum growth and sporulation correlated strongly with the amount of ELISA-detectable elicitin (R (2) = 0.791 and 0.961, respectively).

  6. Composting is an effective treatment option for sanitization of Phytophthora ramorum-infected plant material.

    PubMed

    Swain, S; Harnik, T; Mejia-Chang, M; Hayden, K; Bakx, W; Creque, J; Garbelotto, M

    2006-10-01

    To determine the effects of heat and composting treatments on the viability of the plant pathogen Phytophthora ramorum grown on both artificial and various natural substrates. Phytophthora ramorum was grown on V8 agar, inoculated on bay laurel leaves (Umbellularia californica) and on woody tissues of coast live oak (Quercus agrifolia). Effects on growth, viability and survival were measured as a result of treatment in ovens and compost piles. Direct plating onto PARP medium and pear-baiting techniques were used to determine post-treatment viability. No P. ramorum was recovered at the end of the composting process, regardless of the isolation technique used. By using a PCR assay designed to detect the DNA of P. ramorum, we were able to conclude the pathogen was absent from mature compost and not merely suppressed or dormant. Some heat and composting treatments eliminate P. ramorum to lower than detectable levels on all substrates tested. Composting is an effective treatment option for sanitization of P. ramorum-infected plant material. Assaying for pathogen viability in compost requires a direct test capable of differentiating between pathogen suppression and pathogen elimination.

  7. Monitoring the effectiveness of Phytophthora ramorum eradication treatments in Oregon tanoak forests

    Treesearch

    Ellen Michaels Goheen; Alan Kanaskie; Everett Hansen; Wendy Sutton; Paul Reeser; Nancy Osterbauer

    2013-01-01

    Phytophthora ramorum, the cause of sudden oak death, was first discovered in Oregon forests in July 2001. An aggressive eradication treatment program was immediately put into place on all lands where it was found. Eradication treatments have changed over time as we have learned more about pathogen behavior. Treatment prescriptions currently consist...

  8. Phytophthora ramorum isolated from California bay laurel inflorescences and mistletoe: possible implications relating to disease spread

    Treesearch

    Gary A. Chastagner; Kathy Riley; Norm Dart

    2008-01-01

    Since 2005, we have been studying the spread and development of Phytophthora ramorum at a Christmas tree farm near Los Gatos, California. This research has shown that distance from infected plants, predominantly California bay laurel (Umbellularia californica) (referred to as ?bay? throughout), is an important factor relating to...

  9. Pathways of spread of Phytophthora ramorum in a simulated nursery setting: an update

    Treesearch

    Kurt Heungens; Bjorn Gehesqui& egrave; re; Kris Van Poucke; Annelies Vercauteren; Martine. Maes

    2013-01-01

    European phytosanitary measures as applied to nurseries require that potential host plants within a radius of 2 m of a Phytophthora ramorum-infected plant must be destroyed and that remaining host plants within a radius of 10 m cannot be traded until they are inspected and found to be pest free at further specific inspections. Despite the wide...

  10. Within-field spread of Phytophthora ramorum on rhododendron in nursery settings

    Treesearch

    Kurt Heungens; Isabelle De Dobbelaere; Bjorn Gehesquière; Annelies Vercauteren; Martine Maes

    2010-01-01

    In Europe, Phytophthora ramorum has mostly been detected on rhododendron plants in nurseries. European Union (EU) phytosanitary measures state that potential host plants within a radius of 2 m of an infected plant must be destroyed, and remaining host plants within a radius of 10 m must be quarantined. Despite the lack of research on the spread...

  11. Progress of the Phytophthora ramorum eradication programme in south-western Oregon forests, 2001 - 2009

    Treesearch

    Alan Kanaskie; Everett Hansen; Ellen Michaels Goheen; Nancy Osterbauer; Michael McWilliams; Jon Laine; Michael Thompson; Stacy Savona; Harvey Timeaus; Bill Woosley; Wendy Sutton; Paul Reeser; Rick Schultz; Dan Hilburn

    2011-01-01

    Sudden Oak Death (SOD) disease caused by Phytophthora ramorum Werres, de Cock & Man in't Veld was first discovered in Oregon forests in July 2001. Since then, an interagency team has been attempting to eradicate the pathogen though a programme of early detection (aerial and ground surveys, stream baiting...

  12. Detection and eradication of Phytophthora ramorum from Oregon forests, 2001-2011

    Treesearch

    Alan Kanaskie; Everett Hansen; Ellen Michaels Goheen; Nancy Osterbauer; Michael McWilliams; Jon Laine; Michael Thompson; Stacy Savona; Harvey Timeus; Bill Woosley; Randall Wiese; Wendy Sutton; Paul Reeser; Joe Hulbert; Rick Shultz; Dan Hilburn

    2013-01-01

    Sudden oak death (SOD), caused by Phytophthora ramorum, is lethal to tanoak (Notholithocarpus densiflorus (Hook. & Arn.) Manos, Cannon & S.H. Oh), and threatens this species throughout its range in Oregon. The disease was first discovered in coastal southwest Oregon forests in July 2001. Since then an interagency team...

  13. Contemporary California indian uses for food of species affected by Phytophthora ramorum

    Treesearch

    Beverly R. Ortiz

    2008-01-01

    This paper provides a brief survey of contemporary central and northwest California Indian uses for food of regulated hosts and associated species affected by Phytophthora ramorum, including recipes from Karuk/Shasta/Abenake elder Josephine Peters. It contextualizes these food uses in terms of their on-going significance in cultural, social and...

  14. Biomarkers identify coast live oaks that are resistant to the invasive pathogen Phytophthora ramorum

    Treesearch

    Brice A. McPherson; Sylvia R. Mori; Anna O. Conrad; Stephen Opiyo; Pierluigi Bonello; David L. Wood

    2015-01-01

    California coast live oaks (Quercus agrifolia) trees have suffered large losses from sudden oak death, caused by the introduced oomycete Phytophthora ramorum. In this review paper, we discuss oak plant chemistry as a potential predictor of disease susceptibility. We have recorded an annual mortality rate of three percent in...

  15. Suppression of Phytophthora ramorum infestations through silvicultural treatment in California's north coast

    Treesearch

    Yana Valachovic; Chris Lee; Brendan Twieg; David Rizzo; Richard Cobb; Radoslaw Glebocki

    2013-01-01

    In 2006, three forested sites infested with Phytophthora ramorum in Humboldt County, California were subjected to different combinations of treatments designed to reduce inoculum and control spread. One treatment, consisting of removal of all California bay laurel (Umbellularia californica (Hook. & Arn.) Nutt.) and tanoak...

  16. Understanding the disposal and utilization options for Phytophthora ramorum infested wood

    Treesearch

    John Shelly; Ramnik Singh; Christine Langford; Tad Mason

    2006-01-01

    Removing trees inflicted with the sudden oak death (SOD) disease is often necessary because of hazard issues or homeowner/landowner desires. An alternative to disposal of this material is to find acceptable uses for this diseased material. A series of studies is being conducted to help understand the risk of spreading the Phytophthora ramorum...

  17. Effects of Phytophthora ramorum infection on hydraulic conductivity and tylosis formation in Tanoak sapwood

    Treesearch

    Jennifer Parke; Bradley Collins; Barb Lachenbruch; Everett Hansen

    2010-01-01

    Tanoak (Lithocarpus densiflorus) is highly susceptible to sudden oak death caused by Phytophthora ramorum. Symptoms include dying crowns, bleeding cankers, and, eventually, death of infected trees. The cause of mortality is not well understood, but we showed previously that naturally infected mature trees have reduced sap...

  18. Climate-Host Mapping of Phytophthora ramorum, causal agent of sudden oak death

    Treesearch

    Roger Magarey; Glenn Fowler; Manuel Colunga; Bill Smith; Ross Meentemeyer

    2008-01-01

    We modeled Phytophthora ramorum infection using the North Carolina State University- Animal and Plant Health Inspection Service Plant Pest Forecasting System (NAPPFAST) for the conterminous United States. Our infection model is based on a temperature-moisture response function. The model parameters were: leaf wetness, minimum temperature, optimum...

  19. Effect of plant sterols and tannins on Phytophthora ramorum growth and sporulation

    USDA-ARS?s Scientific Manuscript database

    The acquisition of plant sterols, mediated via elicitins, is required for growth and sporulation of Phytophthora spp. In this paper, we looked at the interaction between elicitins, sterols, and tannins. When ground leaf tissue was added to growth media, P. ramorum growth and sporulation was greates...

  20. An update on microsatellite genotype information of Phytophthora ramorum in Washington State nurseries

    Treesearch

    Katie Coats; Gary Chastagner; Norm Dart; Meg M. Larsen; Niklaus J.. Grunwald

    2010-01-01

    Phytophthora ramorum was first detected in a Washington nursery in 2003 and has since been positively identified in 46 nurseries, three non-nursery water sites, and three landscape sites. Thirteen nurseries have tested positive for 2 consecutive years and four nurseries have been positive for 3 consecutive years, despite the completion of the U...

  1. Green Fluorescent Protein (GFP) as a reporter gene for the plant pathogenic oomycete Phytophthora ramorum

    Treesearch

    Marko Riedel; Gautier Calmin; Lassaad Belbahri; Francois Lefort; Monika Gotz; Stefan Wagner; Sabine. Werres

    2009-01-01

    Transgenic Phytophthora ramorum strains that produce green fluorescent protein (GFP) constitutively were obtained after stable DNA integration using a polyethylene glycol and CaCl2-based transformation protocol. Green fluorescent protein production was studied in developing colonies and in different propagules of the pathogen...

  2. Germination of Phytophthora ramorum chlamydospores: a comparison of separation method and chlamydospore age

    Treesearch

    Justin P. Shaffer; Jennifer L. Parke

    2013-01-01

    Phytophthora ramorum characteristically produces large amounts of chlamydospores in vitro, but the role of these propagules in the disease cycle remains unclear. Germination is difficult to observe and quantify if chlamydospores are not free of mycelium, and the low frequency of germination commonly reported suggests that...

  3. Tracking populations and new infections of Phytophthora ramorum in southern Oregon forests

    Treesearch

    Jennifer Britt; Simone Prospero; Niklaus Grünwald; Alan Kanaskie; Everett Hansen

    2010-01-01

    Since the discovery of Phytophthora ramorum in southern Oregon forests in 2001, newly infested areas are located each year. We tracked the spread and dispersal using DNA fingerprinting. While among site genetic variance was low, we did find changes in genotype presence and frequency at the site level. These genotypic differences allowed us to...

  4. Vegetation dynamics and impacts of Phytophthora ramorum in redwood-tanoak forests in California

    Treesearch

    S Lynch; R Cobb; D. Rizzo

    2009-01-01

    Pathogen epidemiology, community ecology of host species, and land use history all play major roles in the current distribution of Phytophthora ramorum and the extent of damage this pathogen has caused in California forests (Rizzo and others 2005, Meentemeyer and others 2008b). Research on the community ecology and the interaction of...

  5. Forest type influences transmission of Phytophthora ramorum in California oak woodlands

    Treesearch

    J. M. Davidson; H. A. Patterson; A. C. Wickland; E. J. Fichtner; D. M. Rizzo

    2011-01-01

    The transmission ecology of Phytophthora ramorum from bay laurel (Umbellularia californica) leaves was compared between mixed-evergreen and redwood forest types throughout winter and summer disease cycles in central, coastal California. In a preliminary multisite study, we found that abscission rates of infected leaves were higher at mixed...

  6. Metabolite profiling to predict resistance to Phytophthora ramorum in natural populations of coast live oak

    Treesearch

    A. Conrad; B. Mcpherson; D. Wood; S. Opiyo; S. Mori; P. Bonello

    2013-01-01

    Sudden oak death, caused by the invasive oomycete pathogen Phytophthora ramorum, continues to shape the dynamics of coastal populations of oak (Quercus spp.) and tanoak (Notholithocarpus densiflorus (Hook. & Arn.) Manos, Cannon & S.H. Oh) in California and tanoak in southwestern Oregon. Over the...

  7. Ethanol attracts scolytid beetles to Phytophthora ramorum cankers on coast live oak

    Treesearch

    Rick G. Kelsey; Maia M. Beh; David C. Shaw; Daniel K. Manter

    2013-01-01

    Ethanol in sapwood was analyzed along vertical transects, through small spot cankers and larger basal cankers, of Phytophthora ramorum-infected stems of Quercus agrifolia at three sites in California. Trees with large basal cankers, known to attract scolytid beetles, had a 4.3 times higher ethanol level than trees with spot cankers...

  8. Determining the effectiveness of the federal order/interim rule on Phytophthora ramorum dissemination in nurseries

    Treesearch

    Karen Suslow

    2008-01-01

    When we examine the nursery survey data over the past 3 years, we find that in the western states, the number of Phytophthora ramorum-infested nurseries found via nursery inspections or surveys has dropped by more than 0 percent from 2004 to 2006, from 110 nurseries to 50, respectively. The percent of nurseries found to be infested compared to the...

  9. Monitoring of natural outbreaks of Phytophthora ramorum in the United Kingdom.

    Treesearch

    Judith Turner; Alex Appiah; Philip Jennings; Gilli Humphries; Debbie Liddell; Sam McDonough; Jackie Stonehouse; David Lockley; Stephen. Eales

    2006-01-01

    Over 40 outbreaks of Phytophthora ramorum have occurred in managed gardens in the United Kingdom. Three of these sites, one in the southeast of England and two in the southwest, have been closely monitored since October 2003. These sites represented differing disease scenarios at the start of monitoring, as eradication action had already taken...

  10. Evaluation of fungicides for the control of Phytophthora ramorum infecting Rhododendron, Camellia, Viburnum, and Pieris

    Treesearch

    S.A. Tjosvold; D.L. Chambers; S. Koike

    2006-01-01

    Phytophthora ramorum has been detected infecting ornamental hosts in European nurseries and gardens beginning in 1993, and detected in North American nurseries beginning in 2000. Nursery operators need a comprehensive program to insure that nursery stock remain disease free. Fungicides could be part of an integrated pest management approach to meet...

  11. Temperature effects on the onset of sporulation by Phytophthora ramorum on rhododendron Cunningham’s White

    USDA-ARS?s Scientific Manuscript database

    The effect of temperature and moist period on the onset of sporangia production by Phytophthora ramorum on Rhododendron ‘Cunningham’s White’ was examined with misted detached leaves held in humid chambers. Following wound-inoculation with sporangia, leaves were preincubated at 20°C for either 24 or...

  12. Longevity of active Phytophthora ramorum in terminal tree hosts following the removal of primary sporulating hosts

    Treesearch

    Barnaby Wylder; Mick Biddle; Anna Harris; Joan Webber

    2017-01-01

    The Forestry Commission-managed forest estate located in Plym, Devon (southwest England) was one of the first locations in late summer 2009 to have stands of Larix kaempferi (Japanese larch) confirmed as infected with Phytophthora ramorum (EU1 lineage). The 398 ha forest had a high proportion (>30%) of

  13. Eradication of Phytophthora ramorum from Oregon forests: status after 6 years

    Treesearch

    Alan Kanaskie; Ellen Goheen; Nancy Osterbauer; Mike McWilliams; Everett Hansen; Wendy Sutton

    2008-01-01

    Sudden oak death (SOD), caused by Phytophthora ramorum, was first discovered in Oregon forests in July 2001. Since then an interagency team has been working with landowners to eradicate the pathogen by cutting and burning all infected and nearby host plants. During the first two years of the eradication effort, all host vegetation within 15 to 30 m...

  14. Differentiating Phytophthora ramorum and P. kernoviae from other species isolated from foliage of rhododendrons

    USDA-ARS?s Scientific Manuscript database

    Phytophthora species are among plant pathogens that are the most threatening to agriculture. After the discovery of P. ramorum, surveys have identified new species and new reports on Rhododendrons. Based upon propagule production and characteristics and colony growth, a dichotomous key was produce...

  15. Dual RNA-seq of the plant pathogen phytophthora ramorum and its tanoak host

    Treesearch

    Katherine J. Hayden; Matteo Garbelotto; Brian J. Knaus; Richard C. Cronn; Hardeep Rai; Jessica W. Wright

    2014-01-01

    Emergent diseases are an ever-increasing threat to forests and forest ecosystems and necessitate the development of research tools for species that often may have few preexisting resources. We sequenced the mRNA expressed by the sudden oak death pathogen Phytophthora ramorum and its most susceptible forest host, tanoak, within the same tissue at two time points after...

  16. Virulence, sporulation, and elicitin production in three clonal lineages of Phytophthora ramorum

    USDA-ARS?s Scientific Manuscript database

    Phytophthora ramorum populations are clonal and consist of three lineages. Recent studies have shown that the clonal lineages may have varying degrees of aggressiveness on some host species, such as Quercus rubra. In this study, we examined virulence, sporulation and elicitin production of five P. ...

  17. Ethanol attracts scolytid beetles to Phytophthora ramorum cankers on coast live oak

    USDA-ARS?s Scientific Manuscript database

    Technical abstract: Ethanol in sapwood was analyzed along vertical transects, through small spot cankers and larger basal cankers, of Phytophthora ramorum-infected stems of Quercus agrifolia at three sites in California. Trees with large basal cankers, known to attract scolytid beetles, had a 4.3 ti...

  18. Stream Monitoring for Detection of Phytophthora ramorum in Oregon Tanoak Forests

    Treesearch

    W. Sutton; E. M. Hansen; P. W. Reeser; A. Kanaskie

    2009-01-01

    Stream monitoring using leaf baits for early detection of Phytophthora ramorum has been an important part of the Oregon Sudden Oak Death (SOD) program since 2002. Sixty-four streams in and near the Oregon quarantine area in the southwest corner of the state were monitored in 2008. Leaves of rhododendron (Rhododendron macrophyllum...

  19. Population genetic analysis infers mMigration pathways of Phytophthora ramorum in US nurseries

    Treesearch

    Erica M. Goss; Meg Larsen; Gary A. Chastagner; Donald R. Givens; Niklaus J. Grünwald; Barbara Jane Howlett

    2009-01-01

    Recently introduced, exotic plant pathogens may exhibit low genetic diversity and be limited to clonal reproduction. However, rapidly mutating molecular markers such as microsatellites can reveal genetic variation within these populations and be used to model putative migration patterns. Phytophthora ramorum is the exotic pathogen, discovered in...

  20. Enhanced recovery of Phytophthora ramorum from soil following 30 days storage at 4C

    USDA-ARS?s Scientific Manuscript database

    Chlamydospores of Phytophthora ramorum produced by mixing 20 percent V8 juice broth cultures with sand and incubating over a 30 day period were used to infest field soil at densities ranging from 0.2 to 42 chlamydospores per cubic centimeter of soil. Chlamydospore recovery was determined by baiting...

  1. Survival of Phytophthora ramorum hyphae following exposure to temperature extremes and various humidities

    USDA-ARS?s Scientific Manuscript database

    We examined the impact of short-term exposure to high and low temperatures and a range of relative humidities on survival of Phytophthora ramorum hyphae. Spore-free hyphal colonies were grown on dialysis squares atop V8 medium. Relative humidity ranged from 41 – 93% at 20 C and 43 – 86% at 28 C. ...

  2. Review of Current Information Regarding the Phytosanitary Risks of Phytophthora ramorum and North American Conifers

    Treesearch

    Brenda Callan; Shane Sela; Eric Allen

    2008-01-01

    On March 3, 2007 the North American Plant Protection Organization (NAPPO) sponsored a ?Risks to Conifers? discussion panel to review the state of scientific knowledge regarding Phytophthora ramorum Werres, De Cock & Man in 't Veld and conifers and the potential for the pathogen to be transported with conifer forest products moving in...

  3. Adaptive differences between Phytophthora ramorum isolates from Europe and North America: evidence for separate subspecies?

    Treesearch

    Clive Brasier; Susan Kirk; Joan Rose

    2006-01-01

    The comparative risk to trees posed by European (E.U.) versus North American (U.S.) isolates of Phytophthora ramorum, the possible risk posed by genetic recombination between them, and whether European versus North American isolates represented discrete sub-populations was investigated. Population samples of E.U. and U.S. isolates were compared for...

  4. The effects of Phytophthora ramorum infection on hydraulic conductivity and tylosis formation in tanoak sapwood

    Treesearch

    Bradley R. Collins; Jennifer L. Parke; Barb Lachenbruch; Everett M. Hansen

    2009-01-01

    Tanoak (Lithocarpus densiflorus (Hook. and Arn.) Rehder) is highly susceptible to sudden oak death, a disease caused by the oomycete Phytophthora ramorum Werres, De Cock & Man in’t Veld. Symptoms include a dying crown, bleeding cankers, and, eventually, death of infected trees. The cause of mortality is not well understood, but recent research indicates that...

  5. Molecular evolution of an Avirulence Homolog (Avh) gene subfamily in Phytophthora ramorum

    Treesearch

    GossErica M.; Caroline M. Press; Niklaus J. Grünwald

    2008-01-01

    Pathogen effectors can serve a virulence function on behalf of the pathogen or trigger a rapid defense response in resistant hosts. Sequencing of the Phytophthora ramorum genome and subsequent analysis identified a diverse superfamily of approximately 350 genes that are homologous to the four known avirulence genes in plant pathogenic oomycetes and...

  6. Attraction of ambrosia and bark beetles to coast live oaks infected by Phytophthora ramorum

    Treesearch

    Brice A. McPherson; Nadir Erbilgin; David L. Wood; Pavel Svihra; Andrew J. Storer; Richard B. Standiford

    2008-01-01

    Sudden oak death, caused by Phytophthora ramorum (Werres, de Cock & Man in?t Veld), has killed thousands of oaks (Quercus spp.) in coastal California forests since the mid-1990s. Bark and ambrosia beetles that normally colonize dead or severely weakened trees selectively tunnel into the bleeding cankers that are the first...

  7. Extended abstract on the potential for Phytophthora ramorum to infest finished compost

    Treesearch

    Steven Swain; Matteo Garbelotto

    2006-01-01

    The survival rate of Phytophthora ramorum was assessed when introduced at high rates into composts of varying provenance and curing time, produced by both "turned windrow" and "forced air static pile" techniques. Survival in some compost media was high and statistically indistinguishable from positive controls (P

  8. Evaluation of molecular markers for Phytophthora ramorum detection and identification using a standardized library of isolates

    Treesearch

    F.N. Martin; M. Coffey; R. Hamelin; P. Tooley; M. Garbelotto; K. Hughes; T. Kubisiak

    2008-01-01

    A number of molecular diagnostic procedures for detection of Phytophthora ramorum have been reported in the literature. In an effort to evaluate the specificity of 10 of these techniques a standardized DNA library for 317 isolates was assembled that included 60 described species as well as 22 taxonomically unclassified isolates. These were sent blind...

  9. Potential susceptibility of Canadian flora to EU2 lineage of Phytophthora ramorum

    Treesearch

    S.F. Shamoun; G. Sumampong; D. Rioux; A. Schlenzig

    2017-01-01

    A total of 33 host species commonly found in eastern (8) and western (25) Canadian landscapes and forest sites were selected for this study. Detached leaves/needles were inoculated with Phytophthora ramorum EU2 lineage mycelia which was isolated from stream bait near an infected larch plantation in Scotland, UK. There was a large variation in...

  10. Early detection monitoring of Phytophthora ramorum in high-risk forests of California

    Treesearch

    Ross Meentemeyer; Elizabeth Lotz; David M. Rizzo; Kelly Buja; Walter Mark

    2006-01-01

    Early detection monitoring is essential for successful control of invasive organisms. Detection of invasions at an early stage of establishment when a population is small and isolated makes eradication more feasible and less costly. Sudden oak death, caused by the recently described pathogen Phytophthora ramorum, is an emerging forest disease that...

  11. Stand structure and local distribution of Phytophthora ramorum in Oregon forests

    Treesearch

    E. Peterson; M. Botts; E. Hansen

    2009-01-01

    The Phytophthora ramorum eradication program in effect in Oregon has allowed for the rapid detection of new infection foci, typically before they develop within each stand and expand into adjacent sites. Yet despite gallant efforts, new locations that previously harbored no apparent infection have been identified each year since the original...

  12. Relationships between Phytophthora ramorum canker (sudden oak death) and failure potential in coast live oak

    Treesearch

    Tedmund J. Swiecki; Elizabeth Bernhardt; Christiana Drake; Laurence R. Costello

    2006-01-01

    In autumn 2002, we conducted a retrospective study on coast live oak (Quercus agrifolia) failures in Marin County, California, woodlands affected by Phytophthora ramorum canker (sudden oak death). The objectives of this case-control study were to quantify levels of bole, large branch, and root failure in these woodlands and...

  13. Virulence, sporulation, and elicitin production in three clonal lineages of Phytophthora ramorum

    Treesearch

    Daniel Manter; Everett Hansen; Jennifer. Parke

    2010-01-01

    Phytophthora ramorum populations are clonal and consist of three clonal lineages: EU1 is the only lineage found in Europe with a few isolated nursery infections in the USA; NA1 is associated with natural infestations in California and Oregon as well as some nursery infections in North America, and NA2 has a limited distribution and has only...

  14. Variation in susceptibility of Umbellularia californica (Bay Laurel) to Phytophthora ramorum

    Treesearch

    Matthew Meshriy; Daniel Hüberli; Tamar Harnik; Lori Miles; Keefe Reuther; Matteo Garbelotto

    2006-01-01

    Bay laurel (Umbellularia californica) is an important foliar host in terms of spore production and transmission of disease. We designed a bioassay to screen for variation in susceptibility to Phytophthora ramorum among populations of bay laurel collected along the coast of California to southern Oregon and also from Yosemite....

  15. Seasonal trends in response to inoculation of coast live oak with Phytophthora ramorum

    Treesearch

    Richard S. Dodd; Daniel Hüberli; Tamar Y. Harnik; Brenda O' Dell; Matteo Garbelotto

    2006-01-01

    We developed a branch cutting inoculation method to provide a controlled system for studying variation in response to inoculation of coast live oak (Quercus agrifolia) with Phytophthora ramorum. This method has advantages over inoculations of trees in the field, in containing the inoculum and in allowing high levels of replication...

  16. Relationship between field resistance to Phytophthora ramorum and constitutive phenolic chemistry of coast live oak

    Treesearch

    A.M. Nagle; B.A. McPherson; D.L. Wood; M. Garbelotto; A.O. Conrad; S. Opiyo; P. Bonello

    2012-01-01

    Sudden oak death, caused by Phytophthora ramorum, has resulted in high levels of coast live oak (Quercus agrifolia Nee (CLO) mortality. However, some CLO survive in areas with high disease pressure and may thus be resistant. We tested the hypothesis that such field resistant trees contain constitutively higher levels of...

  17. Sudden Oak Death, Phytophthora ramorum: A Persistent Threat to Oaks and Other Tree Species

    Treesearch

    S.J. Frankel; K.M. Palmieri

    2014-01-01

    This paper reviews the status and management of sudden oak death and “sudden larch death” in the urban and wildland forests of California, Oregon, and the UK. The causal pathogen, Phytophthora ramorum, was discovered in all three locations over a decade ago; however, efforts to contain and eliminate infestations have been unsuccessful. These less...

  18. Potential climatic suitability for establishment of Phytophthora ramorum within the contiguous United States

    Treesearch

    Robert C. Venette; Susan D. Cohen

    2006-01-01

    Phytophthora ramorum has caused extensive mortality to tanoak and several oak species in coastal California. This pathogen has infected at least 72 plant species under natural conditions and 32 additional species in the laboratory. Many infected hosts have been distributed across the United States by the horticultural industry. We developed a...

  19. Survival of Phytophthora ramorum in Rhododendron root balls and in rootless substrates

    Treesearch

    A. Vercauteren; M. Riedel; M. Maes; S. Werres; K. Heungens

    2013-01-01

    This study assesses the survival of Phytophthora ramorum in the root ball of Rhododendron container plants as well as in different rootless forest substrates and a horticultural potting medium. Following inoculation of the root balls, the aboveground plant parts stayed symptomless, whilst the pathogen could be recovered with a...

  20. Infectivity and sporulation of Phytophthora ramorum on northern red oak and chestnut oak

    USDA-ARS?s Scientific Manuscript database

    Branches from northern red and chestnut oak seedlings were dip-inoculated with 5,000 sporangia per milliliter of Phytophthora ramorum and incubated at 100 percent relative humidity in dew chambers for 6 days. Three plants were then used to assess sporangia production, while the other three plants w...

  1. Sporulation capacity of Phytophthora ramorum on northern red oak and chestnut oak

    USDA-ARS?s Scientific Manuscript database

    Branches from six 2 to 3-year old northern red and chestnut oak seedlings were dip-inoculated with ca. 5,000 sporangia per milliliter of Phytophthora ramorum isolate Pr-6 and incubated at 100 percent relative humidity in dew chambers for 6 days. Three plants were then used to assess sporangia produ...

  2. Prevalence and development of disease on coast redwood seedlings caused by Phytophthora ramorum

    Treesearch

    S. Lucas; J. Parke; Y. Valachovic

    2009-01-01

    Coast redwood (Sequoia sempervirens) is a host for Phytophthora ramorum but it is unclear if the pathogen represents a significant disease risk to this tree species. In an on-going field experiment, we are examining the prevalence of infection and the development of symptoms on coast redwood seedlings in naturally infested...

  3. The epidemiology of Phytophthora ramorum and P. kernoviae at two historic gardens in Scotland

    Treesearch

    M. Elliot; T.R. Meagher; C. Harris; K. Searle; B.V. Purse; A. Schlenzig

    2013-01-01

    This study looked at the factors that facilitated the spread of Phytophthora ramorum andP. kernoviae at two locations in the west of Scotland. Spore traps, river baiting, bait plants, and soil sampling were used to both confirm the presence of, and measure the amount of, inoculum in the environment in order...

  4. Environmental parameters affecting inoculum production from lilac leaf pieces infected with Phytophthora ramorum

    Treesearch

    Nina Shishkoff

    2008-01-01

    Leaves with lesions caused by Phytophthora ramorum Werres, de Cock & Man in?t Veld often drop off infected plants. Because fallen leaves might serve as sources of inoculum both for the above-ground tissues of host plants and for their roots, this study quantified the inoculum produced by such leaves on the surface of pots when exposed to...

  5. The response of saprotrophic beetles to coast live oaks infected with Phytophthora ramorum

    Treesearch

    Brice A. McPherson; Nadir Ebilgin; David L. Wood; Pavel Svihra; Andrew J. Storer; Richard B. Standiford

    2006-01-01

    Saprotro phic ambrosia and bark beetles (Coleoptera: Scolytidae) tunnel into the bark overlying cankers caused by Phytophthora ramorum in coast live oaks, Quercus agrifolia. These insects are characteristically reported to colonize freshly dead or moribund trees (Furniss and Carolin, 1977). However, the initial attacks by these...

  6. Phytophthora ramorum in coast live oak: search for resistance and mechanisms.

    Treesearch

    B.A. McPherson; D.L. Wood; S.R. Mori; A. Conrad; P. Bonello

    2013-01-01

    Despite the presence of Phytophthora ramorum in northern and central California forests since at least 1994, asymptomatic coast live oaks (Quercus agrifolia Née) still remain in heavily infested stands. Coast live oak infection and mortality rates of 5 percent y-1 and 3 percent y-1, respectively, observed in long-term...

  7. Effects of environmental variables on the survival of Phytophthora ramorum in bay laurel leaves

    Treesearch

    M.V. DiLeo; R.M. Bostock; D.M. Rizzo

    2008-01-01

    Bay laurel (Umbellularia californica (Hook. & Arn.) Nutt.) is the primary reservoir host of Phytophthora ramorum Werres, De Cock & Man n?t Veld in coastal California woodlands. Non-lethal foliar lesions on bay laurel trees support the majority of pathogen sporulation during the winter et season and appear to provide the...

  8. Vegetation response following Phytophthora ramorum eradication treatments in southwest Oregon forests

    Treesearch

    Ellen Michaels Goheen; Everett Hansen; Alan Kanaskie; Wendy Sutton; Paul Reeser

    2008-01-01

    Sudden oak death, caused by Phytophthora ramorum, was identified in late July 2001 in forest stands in Curry County on the southwest Oregon coast where it was killing tanoak (Lithocarpus densiflorus) and infecting Pacific rhododendron (Rhododendron macrophyllum) and evergreen huckleberry (Vaccinium...

  9. Development of Phytophthora ramorum infection and disease symptoms on coast redwood seedlings

    Treesearch

    Sunny Lucas; Jennifer L. Parke; Yana Valachovic

    2008-01-01

    Coast redwood (Sequoia sempervirens) is a host for Phytophthora ramorum but it is not clear if the pathogen represents a significant disease risk to this tree species. In an on-going field experiment, we are examining the process of infection and the development of symptoms on coast edwood seedlings in naturally infested sites in...

  10. Identification of control agents and factors affecting pathogenicity of Phytophthora ramorum

    Treesearch

    Marianne Elliott; Simon F. Shamoun; Grace Sumampong; Delano James; Stephan C. Briere; Saad Masri; Aniko Varga

    2008-01-01

    A collection of 67 isolates of Phytophthora ramorum from the United States (U.S.), European Union (EU), and Canada was screened using differences in phenotypic traits (pathogenicity, growth rate at several temperatures, and sensitivity/resistance to metalaxyl, dimethomorph, and streptomycin) and for presence of cytoplasmic elements (dsRNA and...

  11. Propagule production by Phytophthora ramorum on infected leaves of lilac (Syringa vulgaris)

    USDA-ARS?s Scientific Manuscript database

    Leaves with lesions caused by Phytophthora ramorum often drop off infected plants. Because fallen leaves might serve as sources of inoculum, this study quantified inoculum produced by such leaves on the surface of pots when exposed to different watering regimes or different temperatures. In one ex...

  12. Effectiveness of fungicides in protecting Douglas-fir shoots from infection by Phytophthora ramorum

    Treesearch

    G.A. Chastagner; E.M. Hansen; K.L. Riley; W. Sutton

    2006-01-01

    The effectiveness of 20 systemic and contact fungicides in protecting Douglas-fir seedlings from infection by Phytophthora ramorum was determined. Some systemic products were applied about a week prior to bud break, while most treatments were applied just after bud break. In addition to the fungicides, two surfactants were included in the post-bud...

  13. Root susceptibility and inoculum production from roots of Eastern United States oak species to Phytophthora ramorum

    USDA-ARS?s Scientific Manuscript database

    Little is known about root susceptibility of eastern U.S. tree species to Phytophthora ramorum. In this study, we examined root susceptibility and inoculum production from roots. Sprouted acorns of Q. rubra, Q. palustrus, Q. coccinia, Q. alba, Q. michauxii and Q. prinus were exposed to motile zoos...

  14. Survey of Eastern U.S. native Rhododendron spp. for antagonistic endophytes towards Phytophthora ramorum

    Treesearch

    Timothy L. Widmer

    2013-01-01

    Rhododendron maximum L. and R. catawbiense Michx. are two species that are native to the eastern United States. They can be found throughout the Appalachian Mountain range and during bloom are very important tourist attractions. Phytophthora ramorum is known to be pathogenic to both species, although no...

  15. Detection and eradication of Phytophthora ramorum from Oregon Forests, 2001-2008

    Treesearch

    Alan Kanaskie; Everett Hansen; Ellen Michaels Goheen; Nancy Osterbauer; Michael McWilliams; Jon Laine; Michael Thompson; Stacy Savona; Harvey Timeus; Bill Woosley; Wendy Sutton; Paul Reeser; Rick Shultz; Dan Hilburn

    2010-01-01

    Sudden oak death (SOD), caused by Phytophthora ramorum, was first discovered in Oregon forests by aerial survey in July 2001. Since then an interagency team has been working with landowners to eradicate the pathogen by cutting and burning all infected and nearby host plants. The Oregon SOD program now consists of the following elements: early...

  16. Impacts of Phytophthora ramorum on oaks and tanoaks in Marin County, California forests since 2000

    Treesearch

    Brice A. McPherson; David L. Wood; Maggi Kelly; Sylvia R. Mori; Pavel Svihra; Andrew J. Storer; Richard B. Standiford

    2010-01-01

    The forests of Marin County were among the first in coastal California to be affected by the Phytophthora ramorum epidemic. Although initially observed in 1994 in tanoaks (Lithocarpus densiflorus) and 1995 in coast live oaks (Quercus agrifolia), it is evident from studies of disease progression that the...

  17. Chemical control of Phytophthora ramorum causing foliar disease in hardy nursery stock in the United Kingdom

    Treesearch

    Judith Turner; Philip Jennings; Sam McDonough; Debbie Liddell; Jackie Stonehouse

    2006-01-01

    A range of fungicides have been tested for activity against P. ramorum using both in vitro and in vivo tests. All fungicides had proven activity against Phytophthora species and either had full approval for use on hardy ornamental nursery stock in the United Kingdom, or could be used under the Revised Long Term Arrangements for Extension of Use (2002...

  18. Spatial relationship between Phytophthora ramorum and roads or streams in Oregon tanoak forests

    Treesearch

    Ebba Peterson; Everett Hansen; Alan Kanaskie

    2014-01-01

    The pathogen, Phytophthora ramorum, causal agent of sudden oak death (SOD) of oaks and tanoaks, continues to expand its range within Oregon despite an effort to eradicate it from native forests. With its early detection and prompt removal of infected hosts, the Oregon SOD eradication program has produced a landscape distribution of disease...

  19. Application of rapid onsite PCR (TaqMan) for Phytophthora ramorum under U.S. conditions

    Treesearch

    Kelvin Hughes; Jenny Tomlinson; Neil Boonham; Kelly Ivors; Matteo Garbelotto; Ian Barker

    2006-01-01

    Currently, diagnosis of Phytophthora ramorum involves sending samples to a laboratory for traditional isolation and morphological characterisation, and/or PCR analysis. This can take as long as 2 weeks from sampling to final diagnosis. However, the Plant Health Group, Central Science Laboratory, has produced on-site DNA extraction and real-time PCR (...

  20. Phytophthora ramorum and sudden oak death in California: II. transmission and survival

    Treesearch

    Jennifer M. Davidson; David M. Rizzo; Matteo Garbelotto; Steven Tjosvold; Garey W. Slaughter

    2002-01-01

    The newly discovered Phytophthora ramorum canker disease of oak (Sudden Oak Death Syndrome) threatens millions of acres of California woodlands where coast live oak (Quercus agrifolia), tanoak (Lithocarpus densiflorus), or black oak (Quercus kelloggii) are dominant species. An important step in...

  1. Survival and chlamydospore production of Phytophthora ramorum in California bay laurel leaves

    Treesearch

    E. Fichtner; D. Rizzo; S. Lynch; D. Rizzo; G. Buckles; J. Parke

    2009-01-01

    Sudden oak death manifests as non-lethal foliar lesions on bay laurel (Umbellularia californica), which support sporulation and survival of Phytophthora ramorum in forest ecosystems. The pathogen survives the dry summers in a proportion of attached bay leaves, but the propagules responsible for survival are...

  2. Host phenology and leaf effects on susceptibility of California bay laurel to Phytophthora ramorum

    Treesearch

    Steven F. Johnston; Michael F. Cohen; Tamas Torok; Ross K. Meentemeyer; Nathan E. Rank

    2016-01-01

    Spread of the plant pathogen Phytophthora ramorum, causal agent of the forest disease sudden oak death, is driven by a few competent hosts that support spore production from foliar lesions. The relationship between traits of a principal foliar host, California bay laurel (Umbellularia californica), and susceptibility to

  3. Aerial and ground surveys for mapping the distribution of Phytophthora ramorum in California

    Treesearch

    Jeffrey A. Mai; Walter Mark; Lisa Fischer; Amy Jirka

    2006-01-01

    Since 2001, the USDA Forest Service and California Polytechnic State University, San Luis Obispo have been collaborating for early detection and monitoring of the occurrence of Phytophthora ramorum, the pathogen known to cause sudden oak death (SOD). The effort consists of annual aerial surveys to map hardwood mortality in overstory tree species...

  4. Disease risk of potting media infested with Phytophthora ramorum under nursery conditions

    Treesearch

    S.A. Tjosvold; D.L. Chambers; E.J. Fichtner; S.T. Koike; S.R. Mori

    2009-01-01

    Phytophthora ramorum has been found in potting media of containerized plants; however, the role of infested media on disease development under nursery conditions is unknown. This study assesses pathogen survival, sporulation, and infectivity to rhododendron plants in nursery pots with infected leaf litter that were maintained under greenhouse and...

  5. The novel interaction between Phytophthora ramorum and wildfire elicits elevated ambrosia beetle landing rates on tanoak

    Treesearch

    Maia M. Beh; Margaret Metz; Steven J. Seybold; David Rizzo

    2013-01-01

    Beh, Maia M.; Metz, Margaret; Seybold, Steven J.; Rizzo, David. 2013. The novel interaction between Phytophthora ramorum and wildfire elicits elevated ambrosia beetle landing rates on tanoak. In: Frankel, S.J.; Kliejunas, J.T.; Palmieri, K.M.; Alexander, J.M. tech. coords. Proceedings of the sudden oak death fifth science symposium. Gen. Tech. Rep...

  6. Ethanol attracts scolytid beetles to Phytophthora ramorum cankers on coast live oak [Abstract

    Treesearch

    Rick G. Kelsey; Maia Beh; Dave Shaw; Daniel K. Manter

    2013-01-01

    Successful infection of coast live oak (Quercus agrifolia Née) stems by Phytophthora ramorum results in the formation of a canker visible initially at the bark surface by the release of a dark red to black colored exudate referred to as "bleeding." Bark and ambrosia beetles are often attracted to diseased trees within...

  7. The effect of salinity on the growth, sporulation and infection of Phytophthora ramorum

    USDA-ARS?s Scientific Manuscript database

    Phytophthora ramorum, a threat to Eastern U.S. forests, has been found in waterways outside the boundaries of infested ornamental nurseries. Very little is known about what factors are conducive to its survival and sporulation in water. This study examined the effect of salt on growth, sporulation,...

  8. Pre-epidemic mortality rates for common Phytophthora ramorum host tree species in California

    Treesearch

    T.M. Barrett

    2006-01-01

    Understanding the impacts of Phytophthora ramorum on forests will require knowledge of pre-disease distribution, abundance, and rates of change for affected species. This study estimated pre-epidemic mortality rates for nine common host tree species: bigleaf maple (Acer macrophyllum), California bay laurel (Umbellularia...

  9. Effect of sanitary measures on the survival of Phytophthora ramorum in soil

    Treesearch

    M.M. Aveskamp; P.J.M. Van Baal; J. De Gruyter

    2006-01-01

    In May 2003, a Phytophthora ramorum infested garden in the surroundings of Nijmegen, the Netherlands, was cleared of infected Rhododendron shrubs by cutting the plants back at 30 cm. In an experiment the remaining parts of the Rhododendron plants were treated with thiophanate–methyl, glyphosate or untreated. In the same experiment, the effect of...

  10. Effects of phosphate treatments on the growth of Phytophthora ramorum in tanoak stems

    Treesearch

    Alan Kanaskie; Everett Hansen; Wendy Sutton

    2006-01-01

    In Oregon, tanoak (Lithocarpus densiflorus) is the tree species most susceptible to Phytophthora ramorum, and Sudden Oak Death (SOD) occurs only in forests where tanoak is present. Oregon is attempting to eradicate the pathogen by complete destruction of host plants in and near infested sites. Although the eradication effort has...

  11. Genetic epidemiology of the Sudden Oak Death pathogen Phytophthora ramorum in California

    Treesearch

    S. Mascheretti; P.J.P. Croucher; M. Kozanitas; L. Baker; M. Garbelotto

    2009-01-01

    A total of 669 isolates of Phytophthora ramorum, the pathogen responsible for Sudden Oak Death, were collected from 34 Californian forests and from the ornamental plant-trade. Seven microsatellite markers revealed 82 multilocus genotypes (MGs) of which only three were abundant (>10%). Iteratively collapsing based upon minimum ΦST, yielded five meta-samples and five...

  12. Research on the epidemiology, ecology and management of Phytophthora ramorum in California forests

    Treesearch

    David M. Rizzo

    2006-01-01

    The ultimate goal of Phytophthora ramorum research is to develop disease management strategies. To date, studies have been focused at three management levels: the individual tree, the landscape (or forest stand), and the regional to international scale (Garbelotto and others 2003, Rizzo and Garbelotto 2003, Rizzo and others 2005). I will focus my...

  13. Lineage, temperature, and host species have interacting effects on lesion development in Phytophthora ramorum

    Treesearch

    C. Eyre; K. Hayden; M. Kozanitas; N. Grunwald; M. Garbelotto

    2014-01-01

    There are four recognized clonal lineages of the pathogen Phytophthora ramorum. The two major lineages present in North America are NA1 and NA2. With a few exceptions, NA1 is found in natural forest ecosystems and nurseries, and NA2 is generally restricted to nurseries. Isolates from the NA1 and NA2 lineages were used to infect rhododendron,...

  14. Combining field observations and genetic data to reconstruct the invasion of Phytophthora ramorum in California

    Treesearch

    Peter J.P. Croucher; Silvia Mascheretti; Matteo Garbelotto

    2013-01-01

    Although it has been convincingly shown that forest populations of the pathogen Phytophthora ramorum have undergone a significant bottleneck and reproduce exclusively asexually (Ivors et al. 2004, 2006; Mascheretti et al. 2008), objective results showing that nurseries were the original source of the introduction remain elusive (Mascheretti et al....

  15. Seasonal symptom expression, laboratory detection success, and sporulation potential of Phytophthora ramorum on rhododendron and camellia

    Treesearch

    Steve A. Tjosvold; David L. Chambers; Cheryl L. Blomquist

    2008-01-01

    Camellias and rhododendrons are important nursery and landscape plants and are known to be highly susceptible hosts of the quarantined plant pathogen, Phytophthora ramorum Werres, de Cock & Man In?t Veld. Nursery inspection can not always occur during optimal conditions for the disease and its detection. The goals of this research were to (1)...

  16. Phytophthora ramorum early detection surveys for forests in the United States, 2003-2006

    Treesearch

    S.W. Oak; A.H. Elledge; E.K. Yockey; W.D. Smith; B.M. Tkacz

    2008-01-01

    Risk-based early detection surveys in U.S. forests were conducted between 2003 and 2006 using 100 m vegetation transects. Thirty-nine states surveyed 3,570 locations in states with endemic Phytophthora ramorum; states where the pathogen had been confirmed only in woody ornamental nurseries; and states that had received potentially infected stock but...

  17. Effect of herbicides on production of inoculum and root colonization of plants infected with Phytophthora ramorum

    Treesearch

    Nina Shishkoff

    2013-01-01

    In Oregon, efforts to eradicate Phytophthora ramorum from forested areas have included use of herbicides to kill infected plants. Use of herbicides on disease-infected plants leads to various outcomes, from decreased spread of disease to greater spread of disease, depending on the plant-pathogen system being examined. In this study, viburnum (

  18. Lineage, temperature, and host species have interacting effects on lesion development in Phytophthora ramorum

    USDA-ARS?s Scientific Manuscript database

    There are four recognized clonal lineages of the pathogen Phytophthora ramorum. The two major lineages present in North America are NA1 and NA2. With a few exceptions, NA1 is found in natural forest ecosystems and nurseries, and NA2 is generally restricted to nurseries. Isolates from the NA1 and NA2...

  19. Spatial and temporal aspects of tylosis formation in tanoak inoculated with Phytophthora ramorum

    Treesearch

    Brad Collins; Jennifer Parke

    2008-01-01

    Phytophthora ramorum is an oomycete pathogen that causes sudden oak death in several species of Fagaceae including tanoak (Lithocarpus densiflorus). Symptoms on tanoak include stem cankers and crown death. Stem infection was thought to be restricted to bark and cambium, but has recently been shown to include sapwood....

  20. Spread of infection within tanoak (Lithocarpus densiflorus) trees inoculated with Phytophthora ramorum

    Treesearch

    J. Parke; B. Collins; G. Buckles; E. Hansen; B. Lachenbruch

    2009-01-01

    In an experiment with mature naturally infected tanoak trees, Phytophthora ramorum was observed in sapwood and appeared to interfere with stem water transport (Parke and others 2007). We postulated that colonization of the xylem could contribute to rapid spread within the tree and lead to development of crown mortality symptomatic of...

  1. Beyond ramorum - the other Phytophthoras in western forests

    Treesearch

    Everett Hansen

    2013-01-01

    Little is known about indigenous Phytophthora species in natural ecosystems, although increasing evidence suggests that a diverse, trophically complex, Phytophthora community is important in many forests. In Oregon, 32+ Phytophthora species have been identified from forests. Globally, the number of...

  2. Relationship between resistance to Phytophthora ramorum and constitutive phenolic chemistry in coast live oaks and northern red oaks

    Treesearch

    Annemarie M. Nagle; Matteo Garbelotto; Brice McPherson; David L. Wood; Pierluigi. Bonello

    2010-01-01

    Phytophthora ramorum causes lethal canker diseases and extensive mortality in coast live oak (CLO) (Quercus agrifolia) and tanoak (Lithocarpus densiflorus). No practical controls are available for this disease in non-urban environments. Therefore, characterization of natural resistance is highly...

  3. Phytophthora ramorum infects tanoak sapwood and is associated with reduced sap flux and specific conductivity of xylem

    Treesearch

    Jennifer Parke; Eunsung Oh; Steve Voelker; Everett Hansen; Gerri Buckles; Barb Lachenbruch

    2008-01-01

    Culture, detection with diagnostic PCR, and microscopy demonstrated the presence of Phytophthora ramorum in the sapwood of mature, naturally infected tanoak (Lithocarpus densiflorus) trees in Curry County, Oregon. The pathogen was strongly associated with discolored sapwood (P

  4. First report of the EU1 clonal lineage of Phytophthora ramorum on tanoak in an Oregon forest

    USDA-ARS?s Scientific Manuscript database

    Initially reported in California as the causal agent of sudden oak death (SOD), efforts to limit spread of Phytophthora ramorum in Oregon natural forests have concentrated on quarantine regulations and eradication of the pathogen from infested areas. P. ramorum has four clonal lineages NA1, NA2, EU1...

  5. Comparison of in situ and in vitro baiting assays for Phytophthora ramorum survey of waterways in the southeastern United States

    Treesearch

    Steven Oak; Jaesoon Hwang; Steven Jeffers

    2013-01-01

    In situ baiting with whole, intact leaves of Rhododendron spp. has been employed since 2006 by the National Phytophthora ramorum Early Detection survey of forests (national survey). Using this method, P. ramorum was detected for the first time in national survey waterways draining 12 infested ornamental...

  6. Microsatellite analysis of the EU1 lineage of Phytophthora ramorum in Washington state nurseries, landscapes, and waterways

    Treesearch

    Katie Coats; Marianne Elliott; Gary Chastagner

    2017-01-01

    Microsatellite analysis initially identified genetic variations within the NA1 clonal lineage of Phytophthora ramorum; however, in Washington nurseries, the genetic population of P. ramorum has shifted and is now dominated by two other lineages, NA2 and EU1. In this study, recently identified markers that are more variable, and...

  7. Molecular detection of Phytophthora ramorum by real-time PCR using Taqman, SYBR Green and molecular beacons with three genes

    Treesearch

    G.J. Bilodeau; C.A. Lévesque; A.W.A.M. De Cock; C. Duchaine; G. Kristjansson; R.C. Hamelin

    2006-01-01

    Sudden oak death, caused by Phytophthora ramorum, is a severe disease that can affect numerous species of trees and shrubs. This pathogen has been spread via nursery stock, and quarantine measures are currently in place to prevent further spread. Molecular assays have been developed to rapidly detect and identify P. ramorum, but...

  8. Migration Patterns of the Emerging Plant Pathogen Phytophthora ramorum on the West Coast of the United States of America

    USDA-ARS?s Scientific Manuscript database

    Phytophthora ramorum (Oomycetes) is the causal agent of sudden oak death and ramorum blight on trees, shrubs, and woody ornamentals in the forests of coastal California and southwestern Oregon and in nurseries of California, Oregon, and Washington. In this study, we investigated the genetic structur...

  9. Population structure of the emerging plant pathogen Phytophthora ramorum on the west coast of the United States

    Treesearch

    S. Prospero; E.M. Hansen; N.J. Grünwald; J. Britt; L.M. Winton.

    2009-01-01

    Phytophthora ramorum is a devastating pathogen in native forests in California and southwestern Oregon and in nursery crops in California, Oregon and Washington. In this study we analyzed the population structure of P. ramorum in the west coast (CA, OR, and WA) of the United States by screening 579 isolates recovered...

  10. Factors influencing Phytophthora ramorum infectivity on Umbellularia californica and testing of a defoliation-based control method

    Treesearch

    Christine Windsor Colijn; Michael Cohen; Steve Johnston; Whalen Dillon; Nathan Rank

    2013-01-01

    The primary foliar host for Phytophthora ramorum is California bay laurel, Umbellularia californica (Hook. & Arn.) Nutt., a main reservoir for the pathogen in California woodlands. We investigated environmental and pathogen-mediated influences on incidence and severity of P. ramorum infection of

  11. Phytophthora ramorum is a generalist plant pathogen with differences in virulence between isolates from infectious and dead-end hosts

    Treesearch

    D. Huberli; M. Garbelotto

    2011-01-01

    Variation in virulence was examined among isolates of Phytophthora ramorum from epidemiologically important or infectious (non-oak) and transmissive dead-end (oak) hosts from North America. Twelve isolates representative of the genetic, geographic and host range of P. ramorum in the western United States were inoculated on...

  12. Resequencing of the Phytophthora ramorum genome to characterize genetic variation and population dynamics of the invasive pathogen

    Treesearch

    Jennifer Yuzon; David M. Rizzo; Mathu Malar C; Sucheta Tripathy; Takao Kasuga

    2017-01-01

    Phytophthora ramorum has spread and diversified throughout California’s northwestern coast since its introduction in the 1990s. Tracking the spread of P. ramorum and the functional response of the pathogen to the environment is of particular interest to managing the epidemic. Using genetic tools such as microsatellite...

  13. Testing biological control agents for suppression of Phytophthora ramorum in potting mixes in a simulated nursery environment

    Treesearch

    Marianne Elliott; Gary Chastagner

    2017-01-01

    The spread of Phytophthora ramorum from infested areas in nurseries and landscape sites is commonly associated with the movement of inoculum in water or from the movement of contaminated soils. It has been shown that P. ramorum can survive asymptomatically on roots of containerized plants and in potting media. The development...

  14. Long-term trends in coast live oak and tanoak stands affected by Phytophthora ramorum canker (Sudden Oak Death)

    Treesearch

    Tedmund J. Swiecki; Elizabeth Bernhardt

    2010-01-01

    Permanent plots were established in 2000 to examine how tree and site factors affect risk of Phytophthora ramorum stem canker (sudden oak death [SOD]) and determine how affected stands change over time due to disease. P. ramorum canker was prevalent in the sampled coast live oak (Quercus agrifolia) or...

  15. Comparative Susceptibility of Plants Native to the Appalachian Range of the United States to Inoculation With Phytophthora ramorum

    Treesearch

    R.G. Linderman; Patricia B. de Sá; E.A. Davis

    2008-01-01

    Phytophthora ramorum, cause of sudden oak death of trees or ramorum blight of other plant species, has many hosts. Some geographic regions, such as the Appalachian range of the eastern United States, are considered high risk of becoming infested with the pathogen because known susceptible plants occur there and climatic characteristics appear...

  16. Identification of new polymorphic microsatellite markers in the NA1 and NA2 lineages of Phytophthora ramorum

    Treesearch

    A. Vercauteren; M. Larsen; E. Goss; N. Grunwald; M. Maes; K. Heungens

    2011-01-01

    Phytophthora ramorum is a recently introduced pathogen in Europe and North America consisting of three clonal lineages. Due to the limited intralineage genetic variation, only a few polymorphic markers are available for use in studies involving the epidemiology and evolution of P. ramorum. A total of 159 primer pairs for...

  17. A test system to quantify inoculum in runoff from Phytophthora ramorum-infected plant roots.

    PubMed

    Shishkoff, Nina

    2011-12-01

    Foliar hosts of Phytophthora ramorum are often susceptible to root infection but the epidemiological significance of such infections is unknown. A standardized test system was developed to quantify inoculum in runoff from root-infected Viburnum tinus ?Spring Bouquet? or Rhododendron ?Cunningham's White? cuttings. Cuttings of both species gave off a maximum amount of inoculum 1 to 3 weeks after inoculation. The greatest amount of inoculum was recovered from Viburnum roots that were 48 to 70 days old at the time of inoculation, or roots incubated at 15 to 20?C rather than 25?C. Inoculum in runoff from inoculated Viburnum roots was similar for four different isolates of P. ramorum representing both the NA1 and EU1 lineages. When Rhododendron cuttings were inoculated with P. ramorum, P. citricola, or P. cactorum, inoculum of all three pathogens was recovered from runoff, with the highest amount recovered from plants inoculated with P. citricola, followed by the other two. Compared with the other two pathogens, P. ramorum colonized root tissue to a smaller extent. The epidemiology of root infection by P. ramorum is important in itself but the assay might lend itself for use in risk analysis for root infection of other plant species and evaluation of control measures, and also shed light on other root-infecting Phytophthora spp.

  18. Distribution and etiology of aerial stem infections of Phytophthora ramorum and Phytophthora kernoviae at three woodland sites in the U.K.

    Treesearch

    Anna Brown; Clive Brasier; Sandra Denman; Joan Rose; Susan Kirk; Joan Webber

    2006-01-01

    Phytophthora ramorum and P . kernoviae sp. nov are recently introduced, invasive pathogens in woodlands in southern Britain. P. kernoviae is a newly discovered taxon, previously referred to as Phytophthora taxon C. Both species aggressively infect foliage and shoots of understory rhododendrons...

  19. Host Phenology and Leaf Effects on Susceptibility of California Bay Laurel to Phytophthora ramorum.

    PubMed

    Johnston, Steven F; Cohen, Michael F; Torok, Tamas; Meentemeyer, Ross K; Rank, Nathan E

    2016-01-01

    Spread of the plant pathogen Phytophthora ramorum, causal agent of the forest disease sudden oak death, is driven by a few competent hosts that support spore production from foliar lesions. The relationship between traits of a principal foliar host, California bay laurel (Umbellularia californica), and susceptibility to P. ramorum infection were investigated with multiple P. ramorum isolates and leaves collected from multiple trees in leaf-droplet assays. We examined whether susceptibility varies with season, leaf age, or inoculum position. Bay laurel susceptibility was highest during spring and summer and lowest in winter. Older leaves (>1 year) were more susceptible than younger ones (8 to 11 months). Susceptibility was greater at leaf tips and edges than the middle of the leaf. Leaf surfaces wiped with 70% ethanol were more susceptible to P. ramorum infection than untreated leaf surfaces. Our results indicate that seasonal changes in susceptibility of U. californica significantly influence P. ramorum infection levels. Thus, in addition to environmental variables such as temperature and moisture, variability in host plant susceptibility contributes to disease establishment of P. ramorum.

  20. Mitochondrial genome sequences and comparative genomics ofPhytophthora ramorum and P. sojae

    SciTech Connect

    Martin, Frank N.; Douda, Bensasson; Tyler, Brett M.; Boore,Jeffrey L.

    2007-01-01

    The complete sequences of the mitochondrial genomes of theoomycetes of Phytophthora ramorum and P. sojae were determined during thecourse of their complete nuclear genome sequencing (Tyler, et al. 2006).Both are circular, with sizes of 39,314 bp for P. ramorum and 42,975 bpfor P. sojae. Each contains a total of 37 identifiable protein-encodinggenes, 25 or 26 tRNAs (P. sojae and P. ramorum, respectively)specifying19 amino acids, and a variable number of ORFs (7 for P. ramorum and 12for P. sojae) which are potentially additional functional genes.Non-coding regions comprise approximately 11.5 percent and 18.4 percentof the genomes of P. ramorum and P. sojae, respectively. Relative to P.sojae, there is an inverted repeat of 1,150 bp in P. ramorum thatincludes an unassigned unique ORF, a tRNA gene, and adjacent non-codingsequences, but otherwise the gene order in both species is identical.Comparisons of these genomes with published sequences of the P. infestansmitochondrial genome reveals a number of similarities, but the gene orderin P. infestans differs in two adjacent locations due to inversions.Sequence alignments of the three genomes indicated sequence conservationranging from 75 to 85 percent and that specific regions were morevariable than others.

  1. Effect of fungicides and biocontrol agents on inoculum production and persistence of Phytophthora ramorum on nursery hosts

    Treesearch

    Steve Tjosvold; David Chambers; Gary Chastagner; Marianne. Elliott

    2013-01-01

    Once Phytophthora ramorum is introduced into a nursery on a host, its local spread and establishment is primarily dependent on sporangia and zoospore production. Nursery operators commonly use fungicides to prevent the establishment of Phytophthora –caused diseases, although current research only supports the use of fungicides...

  2. Thermal inactivation of infested plants, nursery equipment, and soil is a management option for the treatment of Phytophthora ramorum, causal agent of sudden oak death

    Treesearch

    Wolfgang Schweigkofler; Vernon Huffman; Karen Suslow; Kathleen Kosta

    2017-01-01

    Infected nursery plants play an important role in the spread of Phytophthora ramorum , the causal agent of sudden oak death and ramorum blight. In order to minimize the risk for disease transmission to new areas, nurseries are inspected regularly for P. ramorum , and federal regulations require the eradication of...

  3. Determining the amount of soilborne inoculum of Phytophthora ramorum within an Oregon tanoak forest

    Treesearch

    Christina Benemann; Jennifer Parke

    2017-01-01

    Phytophthora ramorum continues to cause extensive mortality of tanoaks in southwestern Oregon. Effective management strategies have been developed based on our current understanding of the pathogen’s epidemiology. Local dispersal can occur either by canopy throughfall (“top-down”) or a ground splash (“bottom-up”) pathway. Although the “top...

  4. Cross-species global proteomics reveals conserved and unique processes in Phytophthora sojae and P. ramorum

    SciTech Connect

    Savidor, Alon; Donahoo, Ryan S; Hurtado-Gonzales, Oscar; Land, Miriam L; Shah, Manesh B; Lamour, Kurt H; McDonald, W Hayes

    2008-08-01

    Phytophthora ramorum and Phytophthora sojae are destructive plant pathogens. Phytophthora sojae has a narrow host range whereas P. ramorum has a wide host range. A global proteomic comparison of the vegetative (mycelium) and infective (germinating-cyst) life-stages of P. sojae and P. ramorum was conducted to identify candidate proteins involved in host range, early infection and vegetative growth. Sixty-two candidates for early infection, 26 candidates for vegetative growth, and numerous proteins that may be involved in defining host specificity were identified. In addition, common life stage proteomic trends between the organisms were observed. In mycelia, proteins involved in transport and metabolism of amino acids, carbohydrates and other small molecules were up-regulated. In the germinating cysts, up-regulated proteins associated with lipid transport and metabolism, cytoskeleton and protein synthesis were observed. It appears that the germinating cyst catabolizes lipid reserves through the -oxidation pathway to drive the extensive protein synthesis necessary to produce the germ tube and initiate infection. Once inside the host, the pathogen switches to vegetative growth, where energy is derived from glycolysis and utilized for synthesis of amino acids and other molecules that assist survival in the plant tissue.

  5. Survival of Phytophthora alni, Phytophthora kernoviae, and Phytophthora ramorum in a simulated aquatic environment at different levels of pH.

    PubMed

    Kong, Ping; Lea-Cox, John D; Moorman, Gary W; Hong, Chuanxue

    2012-07-01

    Phytophthora ramorum, Phytophthora alni, and Phytophthora kernoviae present significant threats to biosecurity. As zoosporic oomycetes, these plant pathogens may spread through natural waterways and irrigation systems. However, survival of these pathogens in aquatic systems in response to water quality is not well understood. In this study, we investigated their zoospore survival at pH 3-11 in a 10% Hoagland's solution over a 14-day period. The results showed that all three pathogens were most stable at pH 7, although the populations declined overnight irrespective of pH. Extended survival of these species depended on the tolerance of pH of their germinants. Germinants of P. alni ssp. alni and P. ramorum were more basic tolerant (pH 5-11), while those of P. kernoviae were more acidic tolerant (pH 3-9). These tolerant germinants formed compact hyphae or secondary sporangia to allow longer survival of these pathogens. Long-term survival at a broad pH range suggests that these pathogens, especially P. ramorum, are adapted to an aquatic environment and pose a threat to new production areas through water dispersal. © 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

  6. Phytophthora ramorum tissue colonization studied with fluorescense microscopy

    Treesearch

    M. Riedel; S. Wagner; M. Gotz; L. Belbahri; F. Lefort; S. Werres

    2009-01-01

    The proceeding worldwide spread and the expanding host spectrum of P. ramorum has become a serious threat to natural plant communities. To encounter this threat detailed knowledge about infection pathways and tissue colonization is essential. To analyze these issues, histological studies of infected tissue with epifluorescence microscopy have been...

  7. Histological Examination of Phytophthora ramorum in Notholithocarpus densiflorus Bark Tissues

    Treesearch

    M. Botts

    2010-01-01

    Colonization of N. densiflorus tissues by P. ramorum is not well understood. The pathogen is able to colonize nearly all tissues of this host but it is unclear how a tree is ultimately killed. Because this is such a destructive invasive pathogen, it is important to investigate its pathogenic strategy. Microscopic investigation of xylem colonization has been conducted,...

  8. Stream monitoring for detection of Phytophthora ramorum in Oregon

    Treesearch

    W. Sutton; E.M. Hansen; P. Reeser; A. Kanaskie

    2008-01-01

    Stream monitoring using leaf baits for early detection of P. ramorum is an important part of the Oregon sudden oak death program. About 50 streams in and near the Oregon quarantine area in the southwest corner of the state are currently monitored. Rhododendron and tanoak leaf baits in mesh bags are exchanged every two weeks throughout the year....

  9. Forest type influences transmission of Phytophthora ramorum in California oak woodlands.

    PubMed

    Davidson, Jennifer M; Patterson, Heather A; Wickland, Allison C; Fichtner, Elizabeth J; Rizzo, David M

    2011-04-01

    The transmission ecology of Phytophthora ramorum from bay laurel (Umbellularia californica) leaves was compared between mixed-evergreen and redwood forest types throughout winter and summer disease cycles in central, coastal California. In a preliminary multisite study, we found that abscission rates of infected leaves were higher at mixed-evergreen sites. In addition, final infection counts were slightly higher at mixed-evergreen sites or not significantly different than at redwood sites, in part due to competition from other foliar pathogens at redwood sites. In a subsequent, detailed study of paired sites where P. ramorum was the main foliar pathogen, summer survival of P. ramorum in bay laurel leaves was lower in mixed-evergreen forest due to lower recovery from infected attached leaves and higher abscission rates of infected leaves. Onset of inoculum production and new infections of bay laurel leaves occurred later in mixed-evergreen forest. Mean inoculum levels in rainwater and final infection counts on leaves were higher in redwood forest. Based on these two studies, lower summer survival of reservoir inoculum in bay laurel leaves in mixed-evergreen forest may result in delayed onset of both inoculum production and new infections, leading to slower disease progress in the early rainy season compared with redwood forest. Although final infection counts also will depend on other foliar pathogens and disease history, in sites where P. ramorum is the main foliar pathogen, these transmission patterns suggest higher rates of disease spread in redwood forests during rainy seasons of short or average length.

  10. Inventory and comparative evolution of the ABC superfamily in the genomes of Phytophthora ramorum and Phytophthora sojae.

    PubMed

    Morris, Paul F; Phuntumart, Vipaporn

    2009-05-01

    Automated and manual annotation of the ATP binding cassette (ABC) superfamily in the Phytophthora ramorum and P. sojae genomes has identified 135 and 136 members, respectively, indicating that this family is comparable in size to the Arabidopsis thaliana and rice genomes, and significantly larger than that of two fungal pathogens, Fusarium graminearum and Magnaporthe grisea. The high level of synteny between these oomycete genomes extends to the ABC superfamily, where 108 orthologues were identified by phylogenetic analysis. The largest subfamilies include those most often associated with multidrug resistance. The P. ramorum genome contains 22 multidrug resistance-associated protein (MRP) genes and 49 pleiotropic drug resistance (PDR) genes, while P. sojae contains 20 MRP and 49 PDR genes. Tandem duplication events in the last common ancestor appear to account for much of the expansion of these subfamilies. Recent duplication events in the PDR and ABCG families in both the P. ramorum and the P. sojae genomes indicate that selective expansion of ABC transporters may still be occurring. In other kingdoms, subfamilies define both domain arrangements and proteins having a common phylogenetic origin, but this is not the case for several subfamilies in oomycetes. At least one ABCG type transporter is derived from a PDR transporter, while transporters in the ABCB-half family cluster with transporters from bacterial, plant, and metazoan genomes. Additional examples of transporters that appear to be derived from horizontal transfer events from bacterial genomes include components of transporters associated with iron uptake and DNA repair.

  11. Effect of temperature and moisture period on infection of Rhododendron 'Cunningham's White' by Phytophthora ramorum.

    PubMed

    Tooley, Paul W; Browning, Marsha; Kyde, Kerrie L; Berner, Dana

    2009-09-01

    We investigated the temperature and moisture conditions that allow Phytophthora ramorum to infect Rhododendron 'Cunningham's White'. Most experiments were performed with a single P. ramorum isolate from the NA1 clonal lineage. For whole plants incubated in dew chambers at 10 to 31 degrees C, the greatest proportion of diseased leaves, 77.5%, occurred at the optimum temperature of 20.5 degrees C. Disease occurred over the entire range of temperatures tested, although amounts of disease were minor at the temperature extremes. For whole plants exposed to varying dew periods at 20 degrees C and then incubated at 20 degrees C for 7 days, a dew period as short as 1 h resulted in a small amount of disease; however, at least 4 h of dew were required for >10% of the leaves to become diseased. Moisture periods of 24 and 48 h resulted in the greatest number of diseased leaves. In detached-leaf, temperature-gradient-plate experiments, incubation at 22 degrees C resulted in the greatest disease severity, followed by 18 degrees C and then 14 degrees C. In detached-leaf, moisture-tent experiments, a 1-h moisture period was sufficient to cause disease on 67 to 73% of leaves incubated for 7 days at 20 degrees C. A statistical model for disease development that combined the effects of temperature and moisture period was generated using nonlinear regression. Our results define temperature and moisture conditions which allow infection by P. ramorum on Cunningham's White rhododendron, and show that P. ramorum is able to infect this host over a wide range of temperatures and moisture levels. The results indicate that P. ramorum has the potential to become established in parts of the United States that are outside its current range.

  12. Population Genetic Analysis Infers Migration Pathways of Phytophthora ramorum in US Nurseries

    PubMed Central

    Goss, Erica M.; Larsen, Meg; Chastagner, Gary A.; Givens, Donald R.; Grünwald, Niklaus J.

    2009-01-01

    Recently introduced, exotic plant pathogens may exhibit low genetic diversity and be limited to clonal reproduction. However, rapidly mutating molecular markers such as microsatellites can reveal genetic variation within these populations and be used to model putative migration patterns. Phytophthora ramorum is the exotic pathogen, discovered in the late 1990s, that is responsible for sudden oak death in California forests and ramorum blight of common ornamentals. The nursery trade has moved this pathogen from source populations on the West Coast to locations across the United States, thus risking introduction to other native forests. We examined the genetic diversity of P. ramorum in United States nurseries by microsatellite genotyping 279 isolates collected from 19 states between 2004 and 2007. Of the three known P. ramorum clonal lineages, the most common and genetically diverse lineage in the sample was NA1. Two eastward migration pathways were revealed in the clustering of NA1 isolates into two groups, one containing isolates from Connecticut, Oregon, and Washington and the other isolates from California and the remaining states. This finding is consistent with trace forward analyses conducted by the US Department of Agriculture's Animal and Plant Health Inspection Service. At the same time, genetic diversities in several states equaled those observed in California, Oregon, and Washington and two-thirds of multilocus genotypes exhibited limited geographic distributions, indicating that mutation was common during or subsequent to migration. Together, these data suggest that migration, rapid mutation, and genetic drift all play a role in structuring the genetic diversity of P. ramorum in US nurseries. This work demonstrates that fast-evolving genetic markers can be used to examine the evolutionary processes acting on recently introduced pathogens and to infer their putative migration patterns, thus showing promise for the application of forensics to plant

  13. Evaluation of a rapid diagnostic field test kit for identification of Phytophthora ramorum, P. kernoviae and other Phytophthora species at the point of inspection

    Treesearch

    C.R. Lane; E. Hobden; L. Laurenson; V.C. Barton; K.J.D. Hughes; H. Swan; N. Boonham; A.J. Inman

    2008-01-01

    Plant health regulations to prevent the introduction and spread of Phytophthora ramorum and P. kernoviae require rapid, cost effective diagnostic methods for screening large numbers of plant samples at the time of inspection. Current on-site techniques require expensive equipment, considerable expertise and are not suited for plant...

  14. The importance of understory infection by Phytophthora ramorum as a means of primary disease establishment in Oregon forests

    Treesearch

    E.K. Peterson

    2013-01-01

    Phytophthora ramorum-infested soils have been implicated as a source of primary inoculum in natural ecosystems. Implicit in this pathway is the need for infection of understory vegetation during pathogen establishment, preceding infection of bole hosts. In support of soil dispersal, studies using artificiallyinoculated soils have shown that...

  15. Effect of environmental and seasonal factors on the susceptibility of different rhododendron species and hybrids to Phytophthora ramorum

    Treesearch

    Isabelle De Dobbelaere; Kurt Heungens; Martine Maes

    2008-01-01

    Although Rhododendron is the most important host of Phytophthora ramorum. in Europe, there is little scientific information about the susceptibility levels of different Rhododendron species and cultivars. Increasing this knowledge would help nurseries in the management of the disease and could be used by plant protection services to target their...

  16. PCR-RFLP Markers Identify Three Lineages of the North American and European Populations of Phytophthora ramorum

    USDA-ARS?s Scientific Manuscript database

    Phytophthora ramorum, the cause of Sudden Oak Death, has a wide host range and is found in the northern hemisphere. It is thought to be introduced to North America and Europe, but its origin is unknown. It has three major clonal lineages and two mating types. Sexual reproduction can only occur when ...

  17. A glimpse at future forests: predicting the effects of Phytophthora ramorum on oak forests of southern Appalachia

    Treesearch

    H.L. Spaulding; L.K. Rieske

    2011-01-01

    The highly pathogenic Phytophthora ramorum, causal organism of sudden oak death (SOD), is established in forests of the Pacific Northwest (USA) and is threatening invasion of other regions. Given the breadth of its host range, with dozens of asymptomatic ornamental hosts and with oaks, Quercus spp., in the red oak (Erythrobalanus) subgenus particularly susceptible, we...

  18. Epidemiological modeling of Phytophthora ramorum: network properties of susceptible plant genera movements in the nursery sector of England and Wales

    Treesearch

    Marco Pautasso; Tom Harwood; Mike Shaw; Xiangming Xu; Mike Jeger

    2008-01-01

    Since the first finding of Phytophthora ramorum in the U.K. (on Viburnum tinus, 2002), the pathogen has been reported throughout the country on a variety of susceptible species both in the horticultural sector and in woodlands and historic gardens. The nursery network may have properties which affect the epidemic threshold for...

  19. Evaluation of molecular markers for Phytophthora ramorum detection and identification: Testing for specificity using a standardized library of isolates

    Treesearch

    F.N. Martin; M.D. Coffey; K. Zeller; R.C. Hamelin; P. Tooley; M. Garbelotto; K.J.D. Hughes; T. Kubisiak; G.J. Bilodeau; L. Levy; C. Blomquist; P.H. Berger

    2009-01-01

    Given the importance of Phytophthora ramorum from a regulatory standpoint, it is imperative that molecular markers for pathogen detection are fully tested to evaluate their specificity in detection of the pathogen. In an effort to evaluate 11 reported diagnostic techniques, we assembled a standardized DNA library using accessions from the World...

  20. The effect of moisture on infection of Rhododendron 'Cunningham's White' and Viburnum tinus by zoospores of Phytophthora ramorum

    Treesearch

    Paul W. Tooley; Marsha Browning

    2017-01-01

    We performed studies to determine the effect of leaf wetness on infection of whole plants of Rhododendron 'Cunningham's White' and Viburnum tinus by zoospores of Phytophthora ramorum. We also evaluated the effect of a post-inoculation drying period on infectivity of the two host species with...

  1. Effect of environmental conditions and lesion age on sporulation of Phytophthora ramorum on California bay laurel, rhododendron, and camellia

    Treesearch

    Steve Tjosvold; David Chambers; Sylvia Mori

    2013-01-01

    The objective of our research was to determine the environmental conditions and lesion age favorable for Phytophthora ramorum sporulation under field conditions. For 2 years, new camellia, rhododendron, and California bay laurel (Umbellaria californica (Hook. & Arn.) Nutt.) nursery stock were seasonally inoculated (every 3 months) on foliage....

  2. Survival, dispersal, and potential soil-mediated suppression of Phytophthora ramorum in a California redwood-tanoak forest

    Treesearch

    E. J. Fichtner; S. C. Lynch; D. M. Rizzo

    2009-01-01

    Because the role of soil inoculum of Phytophthora ramorum in the sudden oak death disease cycle is not well understood, this work addresses survival, chlamydospore production, pathogen suppression, and splash dispersal of the pathogen in infested forest soils. Colonized rhododendron and bay laurel leaf disks were placed in mesh sachets before...

  3. Real-time PCR assay to distinguish the four Phytophthora ramorum lineages using cellulose binding elicitor lectin (CBEL) locus

    USDA-ARS?s Scientific Manuscript database

    Phytophthora ramorum is a pathogenic oomycete responsible for causing sudden oak death in the Western United States and sudden larch death in the United Kingdom. This pathogen has so far caused extensive mortality of oak and tanoak in California and of Japanese larch in the United Kingdom. Until rec...

  4. A spatial analysis of Phytophthora ramorum symptom spread using second-order point pattern and GIS-based analyses

    Treesearch

    Mark Spencer; Kevin O' Hara

    2006-01-01

    Phytophthora ramorum is a major source of tanoak (Lithocarpus densiflorus) mortality in the tanoak/redwood (Sequoia sempervirens) forests of central California. This study presents a spatial analysis of the spread of the disease using second-order point pattern and GIS analyses. Our data set includes four plots...

  5. Single-strand conformation polymorphism analysis of ribosomal DNA for detection of Phytophthora ramorum directly from plant tissues

    Treesearch

    Ping Kong; Patricia A. Richardson; Chuanxue Hong; Thomas L. Kubisiak

    2006-01-01

    At the first Sudden Oak Death Science Symposium, we reported on the use of a single strand conformation polymorphism (SSCP) analysis for rapid identification of Phytophthora ramorum in culture. We have since assessed and improved the fingerprinting technique for detecting this pathogen directly from plant tissues. The improved SSCP protocol uses a...

  6. Antimicrobial activity of extracts and select compounds in the heartwood of seven western conifers toward Phytophthora ramorum

    Treesearch

    Daniel K. Manter; Rick G. Kelsey; Joseph J. Karchesy

    2008-01-01

    Previously, we demonstrated that wood chips, essential oil, and four individual compounds from Alaska yellow-cedar (Chamaecyparis nootkatensis [D. Don] Spach) heartwood strongly inhibit the germination f Phytophthora ramorum (Werres, de Cock, Man int Veld) zoospores or sporangia, and reduce hyphal growth in culture (Manter and...

  7. Phytophthora ramorum canker (Sudden Oak Death) disease risk and progress in coast live oak, 2000-2012

    Treesearch

    Tedmund J. Swiecki; Elizabeth Bernhardt

    2015-01-01

    From 2000 through 2012, we collected annual observations on disease symptoms and stand conditions in 128 coast live oak plots in forests affected by sudden oak death (SOD), caused by the introduced pathogen Phytophthora ramorum. Elevated rainfall in one or both of the previous wet seasons was associated with pulses of new infections. However,...

  8. The novel interaction between Phytophthora ramorum and wildfire elicits elevated ambrosia beetle landing rates on tanoak, Notholithocarpus densiflorus

    Treesearch

    Maia M. Beh; Margaret R. Metz; Steven J. Seybold; David M. Rizzo

    2014-01-01

    The 2008 wildfires in the Big Sur region of California’s central coast—the first to occur in forests impacted by Phytophthora ramorum, the non-native, invasive pathogen that causes sudden oak death—provided the rare opportunity to study the response of scolytid and other subcortical beetles to this novel disturbance interaction...

  9. Spatial variation in effects of temperature on Phenotypic characteristics of Phytophthora ramorum isolates from eastern Sonoma county

    Treesearch

    Valerie Sherron; Nathan E. Rank; Michael Cohen; Brian L. Anacker; Ross K. Meentemeyer

    2008-01-01

    Quantifying the growth rates of plant pathogens in the laboratory can be useful for predicting rates of disease spread and impact in nature. The purpose of this study was to examine phenotypic variation among isolates of Phytophthora ramorum collected from a foliar host plant species, Umbellularia californica (California bay laurel...

  10. Magnetic resonance imaging (MRI) of oak trees infected with Phytophthora ramorum to determine potential avenues of infection in bark

    Treesearch

    Edwin R. Florance

    2006-01-01

    Non-destructive magnetic resonance imaging (MRI) revealed pathological anatomical features of coast live oak trees (Quercus agrifolia) that were naturally infected with Phytophthora ramorum. Fresh excised whole slices showing typical macroscopic cankers and bleeding were examined. Infected areas (i.e. cankers) were compared to...

  11. Spatial estimation of the density and carbon content of host populations for Phytophthora ramorum in California and Oregon

    Treesearch

    Sanjay Lamsal; Richard C. Cobb; J. Hall Cushman; Qingmin Meng; David M. Rizzo; Ross K. Meentemeyer.

    2011-01-01

    Outbreak of the emerging infectious disease sudden oak death continues to threaten California and Oregon forests following introduction of the exotic plant pathogen Phytophthora ramorum. Identifying areas at risk and forecasting changes in forest carbon following disease outbreak requires an understanding of the geographical distribution of host...

  12. Research on the quarantine pathogen Phytophthora ramorum at the National Ornamentals Research Site at Dominican University of California

    Treesearch

    Wolfgang Schweigkofler; Kathleen Kosta; Tomas Pastalka; Vernon Huffman; Supriya Sharma; Karen Suslow

    2017-01-01

    The National Ornamentals Research Site at Dominican University of California (NORS-DUC) was founded in the year 2009 by a Farm Bill grant to study Phytophthora ramorum in a sophisticated research nursery that reflects an authentic commercial nursery setting (www.dominican.edu/norsduc). NORS-DUC goals are to develop practical solutions for...

  13. The effects of Phytophthora ramorum stem inoculation on aspects of tanoak physiology and xylem function in saplings and seedlings

    Treesearch

    Elizabeth Stamm

    2012-01-01

    Phytophthora ramorum, an oomycete plant pathogen, is the causal agent of sudden oak death, a serious disease of Fagaceous trees in California and Oregon over the last decade. Tanoak (Notholithocarpus densiflorus) is one of the most susceptible host species, but the cause of host mortality is poorly understood....

  14. Evaluation of molecular markers for Phytophthora ramorum detection and identification; testing for specificity using a standardized library of isolates.

    USDA-ARS?s Scientific Manuscript database

    A number of molecular techniques have been developed for detection of Phytophthora ramorum from infected tissue. These have been based on spacer regions (the rDNA ITS region, the spacer region between the cox I and II gene) or specific genes (beta tubulin, elicitin) and have been configured for use ...

  15. Ancient isolation and independent evolution of the three clonal lineages of the exotic sudden oak death pathogen Phytophthora ramorum

    Treesearch

    E.M. Goss; I. Carbone; N.J. Grünwald

    2009-01-01

    The genus Phytophthora includes some of the most destructive plant pathogens affecting agricultural and native ecosystems and is responsible for a number of recent emerging and re-emerging infectious diseases of plants. Sudden oak death, caused by the exotic pathogen P. ramorum, has caused extensive mortality of oaks...

  16. Progress report on the evaluation of the susceptibility of the holm oak (Quercus ilex) forest ecosystem to Phytophthora ramorum

    Treesearch

    Eduardo Moralejo; Enrique Descals

    2006-01-01

    In preliminary studies on the susceptibility of plant members of the holm oak (Quercus ilex) forest, detached leaves of several woody species were highly susceptible when inoculated with zoospore suspensions of local isolates of Phytophthora ramorum (Moralejo and Hernández 2002). Since then, there have been reports of natural...

  17. Phytophthora ramorum infection in coast live oaks and Shreve's oaks treated with insecticide to prevent beetle colonization

    Treesearch

    Brice A. McPherson; David L. Wood; David M. Rizzo; Pavel Svihra; Steve Tjosvold; Andrew J. Storer; Richard B. Standiford

    2006-01-01

    As the name implies, sudden oak death, caused by Phytophthora ramorum, kills many, if not most of the coast live oaks, Quercus agrifolia, that become infected (McPherson and others, 2005). Several genera of ambrosia and bark beetles (Coleoptera: Scolytidae) colonize bleeding (infected) trees and are suspected to hasten tree death....

  18. Phytophthora ramorum does not cause physiologically significant systemic injury to California bay laurel, its primary reservoir host

    Treesearch

    M. V. DiLeo; R. M. Bostock; D.M. Rizzo

    2009-01-01

    California bay laurel trees (Umbellularia californica) play a crucial role in the reproduction and survival of Phytophthora ramorum in coastal California forests by supporting sporulation during the rainy season and by providing a means for the pathogen to survive the dry, Mediterranean summer. While bay laurel is thus critical to the epidemiology of sudden oak death...

  19. Effects of inoculum density and wounding on stem infection of three eastern US forest species by Phytophthora ramorum

    Treesearch

    P.W. Tooley; M. Browning; R.M. Leighty

    2014-01-01

    Seedlings of three Eastern US forest species Quercus rubra (northern red oak), Quercus prinus (chestnut oak) and Acer rubrum (red maple) were inoculated by applying Phytophthora ramorum sporangia to stems at different inoculum densities with and without wounding. Disease occurred in all...

  20. Population dynamics of aerial and terrestrial populations Phytophthora ramorum in a California forest under different climatic conditions

    Treesearch

    C.A. Eyre; M. Kozanitas; M. Garbelotto

    2013-01-01

    Limited information is available on how soil and leaf populations of the sudden oak death pathogen, Phytophthora ramorum, may differ in their response to changing weather conditions, and their corresponding role in initiating the next disease cycle after unfavorable weather conditions. We sampled and cultured from 425 trees in six sites, three...

  1. Soil moisture and temperature conditions affect survival and sporulation capacity of Rhododendron leaf disks infested with Phytophthora ramorum

    Treesearch

    Ebba K. Peterson; Niklaus J. Grünwald; Jennifer L. ParkeSoil

    2017-01-01

    Soilborne inoculum (infested leaf debris which has become incorporated into the soil) may be an important contributor to the persistence of the sudden oak death pathogen Phytophthora ramorum in recurrently positive nurseries. To initiate new epidemics, soilborne inoculum must not only be able to survive over time, but also be capable of...

  2. The importance of humans in the dispersal and spread of Phytophthora ramorum at local, landscape, and regional scales

    Treesearch

    J. Hall Cushman; Ross Meentemeyer

    2006-01-01

    Determining how Phytophthora ramorum is dispersed across the landscape is critical for understanding the ecology and epidemiology of this influential pathogen. To date, researchers have shown that abiotic factors – such as rain-splash, wind-blown rain and down-stream transport of inoculum – are critical mechanisms for the dispersal of this pathogen....

  3. Dynamics of aerial and terrestrial populations of Phytophthora ramorum in a California watershed under different climatic conditions

    Treesearch

    Catherine A. Eyre; Melina Kozanitas; Matteo Garbelotto

    2013-01-01

    We present a study of the epidemiology of sudden oak death (SOD) in California within a watershed based on temporally and spatially replicated surveys of symptoms, viability of the pathogen from symptomatic leaves, and genetic analyses using polymorphic SSR markers.Phytophthora ramorum is sensitive to climate; its...

  4. Disease risk factors and disease progress in coast live oak and tanoak affected by Phytophthora ramorum canker (sudden oak death)

    Treesearch

    Tedmund J. Swiecki; Elizabeth Bernhardt

    2006-01-01

    This paper reports on five years of observations in a case-control study examining the role of tree and site factors on the development of Phytophthora ramorum stem canker (sudden oak death) in coast live oak (Quercus agrifolia) and tanoak (Lithocarpus densiflorus). In September of each year from 2000 through...

  5. In vitro testing of biological control agents on A1 and A2 isolates of Phytophthora ramorum

    Treesearch

    Marianne Elliott; Simon Shamoun

    2008-01-01

    Biological control products were tested in vitro with six isolates of Phytophthora ramorum. These isolates were geographically diverse and were selected based on their pathogenicity to detached Rhododendron leaves. In addition to five commercially available biocontrol products, nine species of Trichoderma were tested. The in vitro...

  6. Survival of Phytophthora ramorum following wildfires in the sudden oak death-impacted forests of the Big Sur region

    Treesearch

    Maia M. Beh; Margaret Metz; Kerri Frangioso; David Rizzo

    2013-01-01

    The summer of 2008 brought the first wildfires to occur in known Phytophthora ramorum-infested forests in California, with the largest individual fire burning in the Big Sur region of the central coast (Monterey County) (Metz et al. 2011). More than 100,000 ha in Big Sur were ultimately burned that summer, providing a natural experiment to examine...

  7. The search for the origin of Phytophthora ramorum: a first look in Yunnan Province, People's Republic of China

    Treesearch

    Ellen Michaels Goheen; Thomas L. Kubisiak; Wenxia Zhao

    2006-01-01

    Phytophthora ramorum, a previously unknown pathogen, was first seen in Europe on ornamental nursery stock in the early 1990s (Werres and others 2001). It has since been implicated in the death of thousands of oaks (Quercus agrifolia and Q. kelloggii) and tanoaks (Lithocarpus densiflorus) in the...

  8. A high throughput system for the detection of Phytophthora ramorum in susceptible plant species: a preliminary report

    Treesearch

    A. Trippe; E. Berghauer; N. Osterbauer

    2008-01-01

    Phytophthora ramorum is a pathogen of regulatory concern in North America and Europe. In 2004, potentially infected plants were shipped from large, wholesale nurseries on the West Coast (California, Oregon, and Washington) throughout the U.S. This prompted a nationwide survey effort and the adoption of a federal order requiring mandatory inspection...

  9. Estimated economic losses associated with the destruction of plants owing to Phytophthora ramorum quarantine efforts in Washington state

    Treesearch

    N.L. Dart; G.A. Chastagner

    2008-01-01

    The number and retail value of plants destroyed in Washington state nurseries due to Phytophthora ramorum quarantine efforts was estimated using Emergency Action Notification forms (EANs) issued by the United States Department of Agriculture Animal and Plant Health Inspection Service between 2004 and 2005. Data collected from EANs indicate that...

  10. Episodic abiotic stress and Phytophthora ramorum blight in rhododendron: impacts on root infection, symptom expression and chemical management

    Treesearch

    Tatiana Roubtsova; Richard Bostock

    2013-01-01

    Of concern for disease management and certification programs in nursery ornamentals is that roots, when colonized by Phytophthora ramorum, may serve as a potential reservoir of inoculum. An additional complication is that the above ground portion of plants with root infections may be asymptomatic. Our central hypothesis is that mild abiotic...

  11. A Multiple Logistic Regression Model for Predicting the Development of Phytophthora ramorum symptoms in Tanoak (Lithocarpus densiflorus)

    Treesearch

    Mark Spencer; Kevin O' Hara

    2007-01-01

    Phytophthora ramorum attacks tanoak (Lithocarpus densiflorus) in California and Oregon. We present a stand-level study examining the presence of disease symptoms in individual stems. Working with data from four plots in redwood (Sequoia sempervirens)/tanoak forests in Marin County, and three plots in Mendocino...

  12. Increasing distance from California bay laurel reduces the risk and severity of Phytophthora ramorum canker in coast live oak

    Treesearch

    Tedmund J. Swiecki; Elizabeth A. Bernhardt

    2008-01-01

    Foliar infections in California bay (Umbellularia californica) are the most important known source of inoculum contributing to Phytophthora ramorum canker in coast live oak (Quercus agrifolia). This research addressed the question whether there is a ?safe? distance between California bay and coast live oak beyond...

  13. Effects of inoculum density and wounding on stem infection of three Eastern U.S. forest species by Phytophthora ramorum

    USDA-ARS?s Scientific Manuscript database

    Seedlings of three Eastern US forest species (red maple, northern red oak, and chestnut oak) were inoculated by applying Phytophthora ramorum sporangia to stems at different inoculum densities with and without wounding. Disease occurred in all treatments involving wounds, and no disease was observe...

  14. Adaptation of a Phytophthora ramorum Real-Time Polymerase Chain Reaction Assay based on a mitochondrial gene region for use on the Cepheid SmartCycler

    USDA-ARS?s Scientific Manuscript database

    Detection of Phytophthora ramorum (causal agent of sudden oak death) in U.S. commercial nurseries has led to quarantine regulations including inspection of nurseries in infested areas. Since P. ramorum can be difficult to culture from symptomatic tissue, methods such as real-time PCR provide rapid ...

  15. Sentinel plant monitoring of Phytophthora ramorum at a research nursery over a six-year-period indicates limited aerial pathogen spread

    Treesearch

    Tomas Pastalka; Karen Suslow; Wolfgang Schweigkofler

    2017-01-01

    The National Ornamentals Research Site at Dominican University of California (NORS-DUC) is a research nursery that was established in 2009 to study invasive plant pathogens like Phytophthora ramorum, causal agent of sudden oak death and ramorum blight. In order to fulfill federal and state regulations, the possible...

  16. Combining Inferential and Deductive Approaches to Estimate the Potential Geographical Range of the Invasive Plant Pathogen, Phytophthora ramorum

    PubMed Central

    Ireland, Kylie B.; Hardy, Giles E. St. J.; Kriticos, Darren J.

    2013-01-01

    Phytophthora ramorum, an invasive plant pathogen of unknown origin, causes considerable and widespread damage in plant industries and natural ecosystems of the USA and Europe. Estimating the potential geographical range of P. ramorum has been complicated by a lack of biological and geographical data with which to calibrate climatic models. Previous attempts to do so, using either invaded range data or surrogate species approaches, have delivered varying results. A simulation model was developed using CLIMEX to estimate the global climate suitability patterns for establishment of P. ramorum. Growth requirements and stress response parameters were derived from ecophysiological laboratory observations and site-level transmission and disease factors related to climate data in the field. Geographical distribution data from the USA (California and Oregon) and Norway were reserved from model-fitting and used to validate the models. The model suggests that the invasion of P. ramorum in both North America and Europe is still in its infancy and that it is presently occupying a small fraction of its potential range. Phytophthora ramorum appears to be climatically suited to large areas of Africa, Australasia and South America, where it could cause biodiversity and economic losses in plant industries and natural ecosystems with susceptible hosts if introduced. PMID:23667628

  17. The current state of knowledge on operational sanitation measures to lower risk of Phytophthora ramorum spread and the need for further study

    Treesearch

    Yana Valachovic; Dave Rizzo; Brendan Twieg

    2013-01-01

    We are working to evaluate risks associated with human spread of the sudden oak death (SOD) pathogen, Phytophthora ramorum, to currently uninfested areas in California. Port-Orford-cedar (Chamaecyparis lawsoniana (A. Murray) Parl.) root disease (POC RD), caused by Phytophthora lateralis, has brought...

  18. Phytophthora ramorum does not cause physiologically significant systemic injury to California bay laurel, its primary reservoir host.

    PubMed

    DiLeo, M V; Bostock, R M; Rizzo, D M

    2009-11-01

    California bay laurel trees (Umbellularia californica) play a crucial role in the reproduction and survival of Phytophthora ramorum in coastal California forests by supporting sporulation during the rainy season and by providing a means for the pathogen to survive the dry, Mediterranean summer. While bay laurel is thus critical to the epidemiology of sudden oak death and other P. ramorum diseases in California, the relatively minor symptoms observed on this reservoir host suggest that it may not sustain ecologically significant injury itself. The long-term role that P. ramorum will play in California forests will depend in part on the extent to which this pathogen decreases the ecological fitness of bay laurel. Despite the importance of this question, no study has yet investigated in detail the physiological impact that ramorum blight imposes on bay laurel. This experimental study quantifies the impact that P. ramorum has on artificially inoculated bay laurel seedlings with measurements that integrate the full injury that infection with an oomycete may cause: photosynthetic efficiency, total photosynthetic area, and growth. Leaf area and leaf mass were not impacted significantly by infection of P. ramorum. Photosynthetic efficiency was mildly depressed in symptomatic, but not asymptomatic leaves, despite unnaturally high levels of necrosis that were imposed on the seedlings. These results demonstrate that bay laurel trees suffer only minor injury from ramorum blight beyond visible necrotic symptoms. Consequently, it is highly likely that bay laurel will continue to be widely available as a host for P. ramorum in California forests, which has long-term implications for the composition of these forests.

  19. Phenotypic Diversification Is Associated with Host-Induced Transposon Derepression in the Sudden Oak Death Pathogen Phytophthora ramorum

    PubMed Central

    Kasuga, Takao; Kozanitas, Melina; Bui, Mai; Hüberli, Daniel; Rizzo, David M.; Garbelotto, Matteo

    2012-01-01

    The oomycete pathogen Phytophthora ramorum is responsible for sudden oak death (SOD) in California coastal forests. P. ramorum is a generalist pathogen with over 100 known host species. Three or four closely related genotypes of P. ramorum (from a single lineage) were originally introduced in California forests and the pathogen reproduces clonally. Because of this the genetic diversity of P. ramorum is extremely low in Californian forests. However, P. ramorum shows diverse phenotypic variation in colony morphology, colony senescence, and virulence. In this study, we show that phenotypic variation among isolates is associated with the host species from which the microbe was originally cultured. Microarray global mRNA profiling detected derepression of transposable elements (TEs) and down-regulation of crinkler effector homologs (CRNs) in the majority of isolates originating from coast live oak (Quercus agrifolia), but this expression pattern was not observed in isolates from California bay laurel (Umbellularia californica). In some instances, oak and bay laurel isolates originating from the same geographic location had identical genotypes based on multilocus simples sequence repeat (SSR) marker analysis but had different phenotypes. Expression levels of the two marker genes analyzed by quantitative reverse transcription PCR were correlated with originating host species, but not with multilocus genotypes. Because oak is a nontransmissive dead-end host for P. ramorum, our observations are congruent with an epi-transposon hypothesis; that is, physiological stress is triggered on P. ramorum while colonizing oak stems and disrupts epigenetic silencing of TEs. This then results in TE reactivation and possibly genome diversification without significant epidemiological consequences. We propose the P. ramorum-oak host system in California forests as an ad hoc model for epi-transposon mediated diversification. PMID:22529930

  20. Biochemical and Kinetic Characterization of the Eukaryotic Phosphotransacetylase Class IIa Enzyme from Phytophthora ramorum

    PubMed Central

    Taylor, Tonya; Ingram-Smith, Cheryl

    2015-01-01

    Phosphotransacetylase (Pta), a key enzyme in bacterial metabolism, catalyzes the reversible transfer of an acetyl group from acetyl phosphate to coenzyme A (CoA) to produce acetyl-CoA and Pi. Two classes of Pta have been identified based on the absence (PtaI) or presence (PtaII) of an N-terminal regulatory domain. PtaI has been fairly well studied in bacteria and one genus of archaea; however, only the Escherichia coli and Salmonella enterica PtaII enzymes have been biochemically characterized, and they are allosterically regulated. Here, we describe the first biochemical and kinetic characterization of a eukaryotic Pta from the oomycete Phytophthora ramorum. The two Ptas from P. ramorum, designated PrPtaII1 and PrPtaII2, both belong to class II. PrPtaII1 displayed positive cooperativity for both acetyl phosphate and CoA and is allosterically regulated. We compared the effects of different metabolites on PrPtaII1 and the S. enterica PtaII and found that, although the N-terminal regulatory domains share only 19% identity, both enzymes are inhibited by ATP, NADP, NADH, phosphoenolpyruvate (PEP), and pyruvate in the acetyl-CoA/Pi-forming direction but are differentially regulated by AMP. Phylogenetic analysis of bacterial, archaeal, and eukaryotic sequences identified four subtypes of PtaII based on the presence or absence of the P-loop and DRTGG subdomains within the N-terminal regulatory domain. Although the E. coli, S. enterica, and P. ramorum enzymes all belong to the IIa subclass, our kinetic analysis has indicated that enzymes within a subclass can still display differences in their allosteric regulation. PMID:25956919

  1. Stromata, sporangiomata and chlamydosori of Phytophthora ramorum on inoculated Mediterranean woody plants.

    PubMed

    Moralejo, Eduardo; Puig, Miquel; García, José A; Descals, Enrique

    2006-11-01

    Three types of multihyphal structures, stromata, sporangiomata and chlamydosori, are described for the plant pathogen Phytophthora ramorum. Their morphology, morphogenesis and position on the host organ were observed by dissecting, compound and scanning electron microscopy. Stromata were consistently formed one to two weeks after zoospore inoculation of detached leaves and fruits of an assortment of Mediterranean sclerophyll shrubs. Stroma initials appeared subcuticularly or subepidermally and developed as small hyphal aggregates by repeated branching, budding, swelling and interweaving, eventually forming a prosenchyma. They always emerged through the adaxial side of the leaf by rupture of the overlying host tissue. Occasionally sporangia and chlamydosori (packed clusters of chlamydospores) were formed on the stromata. Sporangiomata bore short sporangiophores and clusters of 20-100 sporangia and resembled sporodochia of the mitosporic fungi. The biological significance of these multihyphal structures is discussed. Some epidemiological aspects were also studied: several understorey species of the holm oak (Quercus ilex) woodland were susceptible to in vitro infection with three isolates of P. ramorum originally collected from different ornamental hosts. The risk of spread to this ecosystem is evaluated.

  2. Growth and sporulation of Phytophthora ramorum in vitro in response to temperature and light.

    PubMed

    Englander, Larry; Browning, Marsha; Tooley, Paul W

    2006-01-01

    Phytophthora ramorum, recently found in the US, is causing concern for hardwood forests and the nursery industry. In an effort to identify some of the environmental limitations to growth and sporulation we undertook a laboratory study of four US and three European (EU) isolates. On V8 media, isolates grew when incubated at 2-28 C and produced chlamydospores at 8-28 C. Sporangia were produced at all temperatures tested: 10-30 C for US isolates and 6-26 C for EU isolates. Optimal temperatures were 16-26 C for growth, 14-26 C for chlamydospore production and 16-22 C for sporangia production. US isolates grew less and produced fewer spores when exposed to increasing doses of near-UV radiation (50-300 microW/cm(2)) and visible radiation (250-1500 microW/cm(2)). EU isolates were exposed to 300 microW/cm(2) near-UV only, which significantly reduced growth of one of three isolates and had no significant effect on spore production. In our studies P. ramorum tolerated a broad range of temperature and light conditions, which suggests that it is capable of establishment in a wide geographic area.

  3. A five-minute DNA extraction method for expedited detection of Phytophthora ramorum following prescreening using Phytophthora spp. lateral flow devices.

    PubMed

    Tomlinson, J A; Dickinson, M; Hobden, E; Robinson, S; Giltrap, P M; Boonham, N

    2010-05-01

    In a direct comparison with established methods for Phytophthora ramorum detection (isolation followed by morphological identification, or conventional DNA extraction followed by TaqMan real-time PCR) a rapid, simplified detection method in which membranes of lateral flow devices (LFDs) are added directly to TaqMan real-time PCR reactions was used to test 202 plant samples collected by plant health inspectors in the field. P. ramorum prevalence within the 202 samples was approximately 40% according to routine testing by isolation or TaqMan real-time PCR. The diagnostic sensitivity and specificity of the rapid detection method were 96.3% and 91.2%, respectively. This method can be used in conjunction with Phytophthora spp. lateral flow devices to reduce the number of samples requiring testing using more laborious conventional methods. The effect of combining prescreening for Phytophthora spp. with P. ramorum-specific tests is discussed in terms of the positive and negative predictive values of species-specific detection when testing samples collected in different inspection scenarios. Crown Copyright 2010. Published by Elsevier B.V. All rights reserved.

  4. Ethanol attracts scolytid beetles to Phytophthora ramorum cankers on coast live oak.

    PubMed

    Kelsey, Rick G; Beh, Maia M; Shaw, David C; Manter, Daniel K

    2013-04-01

    Ethanol in sapwood was analyzed along vertical transects, through small spot cankers and larger basal cankers, of Phytophthora ramorum-infected stems of Quercus agrifolia at three sites in California. Trees with large basal cankers, known to attract scolytid beetles, had a 4.3 times higher ethanol level than trees with spot cankers that attract fewer beetles. Ethanol concentrations inside cankers, where scolytid beetles preferentially attack, varied by about four orders of magnitude among samples, with a median level of 16.0 μg.g(-1) fresh mass. This concentration was 4.3 and 15.5 times greater, respectively, than the concentrations at 1 cm or 15-30 cm outside the canker boundaries. In the laboratory, we demonstrated that ethanol escaped through the bark of a Q. garryana log just 3 days after it was added to the sapwood. At the three study sites, traps baited with ethanol captured more Xyleborinus saxesenii, Pseudopityophthorus pubipennis, and Monarthrum dentiger (all Coleoptera: Curculionidae: Scolytinae) than traps baited with ethanol plus (-)-α-pinene, or ethanol plus 4-allylanisole (4AA). Logs of Q. agrifolia with a 50 % ethanol solution added to the sapwood were placed at the study sites, with or without additional bark treatments above the ethanol. The number of scolytid beetle gallery holes above the ethanol-infused sapwood was 4.4 times greater than that on the opposite side of the log where no ethanol was added. Attachment of ultra-high release (-)-α-pinene pouches to the bark surface above the 50 % ethanol solution reduced scolytid attacks to a density of 19.1 % that of logs without this treatment. We conclude that ethanol in P. ramorum cankers functions as a primary host attractant for scolytid beetles and is an important link in colonization of these cankers and accelerated mortality of Q. agrifolia. The results of this research shed light on the chemical ecology behind the focused scolytid attacks on P. ramorum-infected coast live oaks, and lay the

  5. Determining landscape-scale changes in forest structure and possible management responses to Phytophthora ramorum in the Mt. Tamalpais watershed, Marin County, California

    Treesearch

    Janet Klein; Andrea Williams; John Menke

    2013-01-01

    The Marin Municipal Water District's (MMWD) 7487 ha Mt. Tamalpais watershed in Marin County, California has the dubious distinction of being one of the earliest and most extensive areas impacted by Phytophthora ramorum in California. Rapid die off of tanoaks (Notholithocarpus densiflorus (Hook. & Arn.) Manos, Cannon...

  6. Importance of rainfall and sprinkler irrigation in supporting sporulation, spread of inoculum in runoff-water, and new infections of Phytophthora ramorum under field conditions

    Treesearch

    Steve Tjosvold; David Chambers; Elizabeth. Fichtner

    2010-01-01

    If a nursery plant infected with Phytophthora ramorum is introduced in a non-infested area, then it is important to understand what environmental conditions could lead spread and infection of new hosts. Once an infected nursery plant is introduced in a nursery or landscape, moving water sources, such as from rain and irrigation events, could...

  7. Incubation of Phytophthora ramorum-infested leaf debris in soil affects survival, sporulation capacity, and subsequent risk of epidemic development within nurseries

    Treesearch

    Ebba K. Peterson; Niklaus J. Grünwald; Jennifer L. Parke

    2017-01-01

    Soilborne inoculum (infested leaf debris which has become incorporated into the soil) may be an important contributor to the persistence of the sudden oak death pathogen Phytophthora ramorum in recurrently positive nurseries. To initiate new epidemics, soilborne inoculum must not only be able to survive over time, but also be capable of producing...

  8. Management of Phytophthora ramorum at plot and landscape scales for disease control, tanoak conservation, and forest restoration - insights from epidemiological and ecosystem models

    Treesearch

    João A.N. Filipe; Richard C. Cobb; Maëlle Salmon; David M. Rizzo; Christopher A. Gilligan

    2013-01-01

    Phytophthora ramorum has continued to spread in forests in the western United States, the United Kingdom, and the Republic of Ireland, and continues to challenge vegetation and ecosystems in temperate regions (Brasier and Webber 2010, Grünwald et al. 2012). Disease management in the wild has been applied with some success in localized outbreaks in...

  9. Disease on nursery stock as affected by environmental factors and seasonal inoculum levels of Phytophthora ramorum in stream water used for irrigation

    Treesearch

    S.A. Tjosvold; D.L. Chambers; S.T. Koike; S.R. Mori

    2008-01-01

    A pear bait monitoring system was used to detect and quantify Phytophthora ramorum propagules in streams that flow through woodland areas with sudden oak death in Santa Cruz County, CA from 2001 to 2007. Stream propagules were detected most frequently or occurred in highest concentrations in winter and spring. The stream propagule concentration was...

  10. This tree is not big enough for the both of us: symptoms of Phytophthora ramorum on California bay laurel are lower when insect herbivores are abundant

    Treesearch

    Kerry E. Wininger; Nathan Rank

    2017-01-01

    Leaves of California bay laurel (Umbellularia californica) are considered the primary natural source of inoculum for the devastating forest disease sudden oak death (Phytophthora ramorum), and yet this plant and the insects associated with its leaves remain understudied. This is unfortunate due to the role herbivorous...

  11. Pyracantha ‘Mohave’ fruit infection by Phytophthora ramorum and transmission of the pathogen from infected fruit to roots of Viburnum tinus

    USDA-ARS?s Scientific Manuscript database

    We conducted a study to investigate the potential role of Pyracantha ‘Mohave’fruit as a source of inoculum for subsequent root infection of a susceptible host by Phytophthora ramorum. An examination of the fleshy pulp revealed an abundance of chlamydospores in fruit following inoculation with P. ra...

  12. Evaluation of stem water potential and other tree and stand variables as risk factors for Phytophthora ramorum canker development in coast live oak

    Treesearch

    Tedmund J. Swiecki; Elizabeth Bernhardt

    2002-01-01

    We conducted a case-control study to examine the role of water stress and various other factors on the development of Phytophthora ramorum cankers in symptomatic (case) and symptomless (control) coast live oak (Quercus agrifolia) and tanoak (Lithocarpus densiflorus). Midday stem water potential (SWP) in ...

  13. Reducing the spread of Phytophthora ramorum on the Redwood Nature Trail, Rogue River-Siskiyou National Forest, Curry County, Oregon: A Case Study

    Treesearch

    Ellen Michaels Goheen

    2013-01-01

    In late August 2009, a 20.3 cm (8 in) diameter tanoak (Notholithocarpus densiflorus (Hook. & Arn.) Manos, Cannon & S.H. Oh) adjacent to a popular hiking trail on the Rogue River-Siskiyou National Forest was found infected with Phytophthora ramorum. The trail was immediately closed to the public. An eradication treatment...

  14. Comparison of the recovery of Phytophthora ramorum from tanoak and California bay laurel, and the potential recovery of inoculum in fog

    Treesearch

    E.K. Peterson; E.M. Hansen; W. Sutton; P.W. Reeser; J.M. Hulbert

    2013-01-01

    Oregon's sudden oak death (SOD) eradication program has focused its efforts upon the aggressive treatment of tanoak (Notholithocarpus densiflorus (Hook.& Arn.) Manos, Cannon & S.H. Oh) over all other host species in its efforts to control the spread of Phytophthora ramorum. Despite its known importance to the...

  15. Host-induced genome alterations in Phytophthora ramorum, I. NA1 lineage on coast live oak in California, II. EU1 lineage on Chamaecyparis lawsoniana in UK

    Treesearch

    Takao Kasuga; Mai Bui; Elizabeth Bernhardt; Tedmund Swiecki; Kamyar Aram; Lien Bertier; Jennifer Yuzon; Liliana M. Cano; Joan Webber; Clive Brasier; Caroline Press; Niklaus Grünwald; David Rizzo; Matteo Garbelotto

    2017-01-01

    Rapid phenotypic diversification in clonal invasive populations is often observed, although the underlying genetic mechanisms remain elusive. Lineages of the sudden oak death pathogen Phytophthora ramorum are exclusively clonal, yet isolates of the NA1 lineage from oak (Quercus spp.) frequently exhibit...

  16. Patterns of tanoak acorn production in Phytophthora ramorum infested and uninfested stands in Big Sur, California, with insights from girdled tanoaks

    Treesearch

    Leila Hadj-Chikh; Kerri Frangioso; Keyt Fischer; Sarah Bergemann; Ebba Peterson

    2006-01-01

    Although tanoak (Lithocarpus densiflorus) acorns are a valuable source of food for many species of wildlife few data on tanoak acorn production exist. We conducted studies of acorn production in tanoaks to understand the potential impact of Phytophthora ramorum on acorn availability to wildlife. In 2002 we established 3-ha seed-...

  17. Regulatory considerations in assessing the potential for Phytophthora ramorum to cause environmental impact to ecozones outside the west coast "fog belt" in North America

    Treesearch

    John McDonald; Gary Kristjansson; Stephen Miller; Shane Sela

    2010-01-01

    Sudden oak death (SOD) is a disease caused by Phytophthora ramorum that is characterized by lethal trunk lesions that affect tanoak (Lithocarpus densiflorus), and a few oak species, principally coast live oak (Quercus agrifolia). It was first observed in Marin County, California, in 1994, and now has been...

  18. Susceptibility to Phytophthora ramorum in a key infectious host: landscape variation in host genotype, host phenotype, and environmental factors.

    PubMed

    Anacker, Brian L; Rank, Nathan E; Hüberli, Daniel; Garbelotto, Matteo; Gordon, Sarah; Harnik, Tami; Whitkus, Richard; Meentemeyer, Ross

    2008-01-01

    Sudden oak death is an emerging forest disease caused by the invasive pathogen Phytophthora ramorum. Genetic and environmental factors affecting susceptibility to P. ramorum in the key inoculum-producing host tree Umbellularia californica (bay laurel) were examined across a heterogeneous landscape in California, USA. Laboratory susceptibility trials were conducted on detached leaves and assessed field disease levels for 97 host trees from 12 225-m(2) plots. Genotype and phenotype characteristics were assessed for each tree. Effects of plot-level environmental conditions (understory microclimate, amount of solar radiation and topographic moisture potential) on disease expression were also evaluated. Susceptibility varied significantly among U. californica trees, with a fivefold difference in leaf lesion size. Lesion size was positively related to leaf area, but not to other phenotypic traits or to field disease level. Genetic diversity was structured at three spatial scales, but primarily among individuals within plots. Lesion size was significantly related to amplified fragment length polymorphism (AFLP) markers, but local environment explained most variation in field disease level. Thus, substantial genetic variation in susceptibility to P. ramorum occurs in its principal foliar host U. californica, but local environment mediates expression of susceptibility in nature.

  19. Tracking populations of Phytophthora ramorum within trees and across the South-western Oregon tanoak (Notholithocarpus densiflorus) forest with DNA fingerprinting and the relative fitness of dominant and rare individuals

    Treesearch

    Jennifer Britt; Everett Hansen

    2011-01-01

    Since the discovery of Phytophthora ramorum Werres, De Cock & Man In't Veld in south-western Oregon forests in 2001, newly infected areas are detected each year. Yet, there are still gaps in our knowledge about how the pathogen spreads or where new infections come from. Our study aims to track the spread of P. ramorum...

  20. Potential for sexual reproduction of Phytophthora ramorum in Washington state nurseries

    Treesearch

    Matteo Garbelotto; Kelly Ivors; Daniel Hüberli; Peter Bonants; Art Wagner

    2006-01-01

    In 2003, isolates belonging to the Al mating type were reported from commercial nurseries in Oregon. Soon thereafter, we reported the presence of both mating types of P. ramorum in nurseries in Washington. AFLP, microsatellite, and RFLP of the Cox I region indicated the Al isolates belonged to the European (E.U.) lineage of P. ramorum...

  1. Detecting Phytophthora ramorum and other species of Phytophthora in Streams in natural ecosystems using baiting and filtration methods

    Treesearch

    Jaesoon Hwang; Steven W. Oak; Steven Jeffers

    2008-01-01

    Phytophthora spp. occur widely in forest and other natural ecosystems. Because these straminipiles are well adapted to aquatic environments, monitoring strategically selected streams may reflect occurrence and distribution of Phytophthora spp. over the relatively large area drained by these streams. The mountain region of western...

  2. Survival, dispersal, and potential soil-mediated suppression of Phytophthora ramorum in a California redwood-tanoak forest.

    PubMed

    Fichtner, E J; Lynch, S C; Rizzo, D M

    2009-05-01

    Because the role of soil inoculum of Phytophthora ramorum in the sudden oak death disease cycle is not well understood, this work addresses survival, chlamydospore production, pathogen suppression, and splash dispersal of the pathogen in infested forest soils. Colonized rhododendron and bay laurel leaf disks were placed in mesh sachets before transfer to the field in January 2005 and 2006. Sachets were placed under tanoak, bay laurel, and redwood at three vertical locations: leaf litter surface, litter-soil interface, and below the soil surface. Sachets were retrieved after 4, 8, 20, and 49 weeks. Pathogen survival was higher in rhododendron leaf tissue than in bay tissue, with >80% survival observed in rhododendron tissue after 49 weeks in the field. Chlamydospore production was determined by clearing infected tissue in KOH. Moist redwood-associated soils suppressed chlamydospore production. Rain events splashed inoculum as high as 30 cm from the soil surface, inciting aerial infection of bay laurel and tanoak. Leaf litter may provide an incomplete barrier to splash dispersal. This 2-year study illustrates annual P. ramorum survival in soil and the suppressive nature of redwood-associated soils to chlamydospore production. Infested soil may serve as primary inoculum for foliar infections by splash dispersal during rain events.

  3. Microclimate Impacts Survival and Prevalence of Phytophthora ramorum in Umbellularia californica, a Key Reservoir Host of Sudden Oak Death in Northern California Forests

    PubMed Central

    DiLeo, Matthew V.; Bostock, Richard M.; Rizzo, David M.

    2014-01-01

    Phytophthora ramorum, an invasive pathogen and the causal agent of Sudden Oak Death, has become established in mixed-evergreen and redwood forests in coastal northern California. While oak and tanoak mortality is the most visible indication of P. ramorum’s presence, epidemics are largely driven by the presence of bay laurel (Umbellularia californica), a reservoir host that supports both prolific sporulation in the winter wet season and survival during the summer dry season. In order to better understand how over-summer survival of the pathogen contributes to variability in the severity of annual epidemics, we monitored the viability of P. ramorum leaf infections over three years along with coincident microclimate. The proportion of symptomatic bay laurel leaves that contained viable infections decreased during the first summer dry season and remained low for the following two years, likely due to the absence of conducive wet season weather during the study period. Over-summer survival of P. ramorum was positively correlated with high percent canopy cover, less negative bay leaf water potential and few days exceeding 30°C but was not significantly different between mixed-evergreen and redwood forest ecosystems. Decreased summer survival of P. ramorum in exposed locations and during unusually hot summers likely contributes to the observed spatiotemporal heterogeneity of P. ramorum epidemics. PMID:25098281

  4. Susceptibility of some native plant species from Hawaii to Phytophthora ramorum

    Treesearch

    Paul Reeser; Everett Hansen; Wendy Sutton; Jennifer Davidson; Jennifer Parke

    2008-01-01

    The remaining native flora of Hawaii are under continuing pressure from habitat loss and exotic, invasive organisms, including animals, plants, and pathogens. In order to assess the risk to P. ramorum, we inoculated seedlings of Metrosideros polymorpha (ohia), Vaccinium calycinum (ohelo), Acacia koa...

  5. The effect of temperature on germination of chlamydospores of Phytophthora ramorum

    USDA-ARS?s Scientific Manuscript database

    Mycelium-free chlamydospores of twelve isolates of P. ramorum representing three clonal lineages (NA-1, NA-2, and EU-1) were produced using a method involving incubation in non-sterile sand at 20 C in darkness for 30 days. Chlamydospores were incubated on selective agar medium in incubators at 5, 10...

  6. Inoculum density effects on infection of selected Eastern US forest species by Phytophthora ramorum

    USDA-ARS?s Scientific Manuscript database

    Inoculum threshold information can be used to better understand the epidemiology of P. ramorum should it become established in the Eastern US. Detached leaves from Quercus prinus, Q. rubra, Acer rubrum, Kalmia latifolia ‘Hoffman’s K’, and Rhododendron ‘Cunningham’s White’ were exposed to sporangia ...

  7. Detection of Phytophthora ramorum chlamydospores in soil by baiting and dilution plating

    USDA-ARS?s Scientific Manuscript database

    Chlamydospores of P. ramorum produced by mixing 20 percent V8 juice broth cultures with sand and incubating over a 1 month period were used to infest field soil at concentrations ranging from 0.2 to 42 chlamydospores/cc soil. Chlamydospore recovery was determined by baiting with rhododendron leaf d...

  8. Inoculum density relationships for infection of some Eastern forest species by Phytophthora ramorum

    USDA-ARS?s Scientific Manuscript database

    The objectives of this work were to establish inoculum density relationships between P. ramorum and selected hosts using detached leaf and whole plant inoculations. Knowledge of levels of initial inoculum needed to generate epidemics is needed for disease prediction and development of pest risk ass...

  9. Inoculum Density Relationships for Infection of Some Eastern US Forest Species by Phytophthora ramorum

    Treesearch

    Paul Tooley; Marsha Browning; Robert Leighty

    2013-01-01

    Our objectives were to establish inoculum density relationships between P. ramorum and selected hosts using detached leaf and whole-plant inoculations. Young plants and detached leaves of Quercus prinus (Chestnut oak), Q. rubra (Northern red oak), Acer rubrum (red maple), ...

  10. Phytophthora ramorum--economic impacts and challenges for the nursery industry

    Treesearch

    Karen Suslow

    2006-01-01

    In March 2004, a large wholesale nursery in southern California, which ships to interstate receivers, was found to have P. ramorum infected nursery stock. As a result, several of the southeastern states placed a ban on all nursery stock shipping from California. Federal regulatory agencies were not able to provide background information and current...

  11. Effectiveness of fungicides in protecting conifers and rhododendrons from Phytophthora ramorum

    Treesearch

    Gary A. Chastagner; Annie DeBauw; Kathy Riley; Norm Dart

    2008-01-01

    The effectiveness of 19 fungicides in protecting noble fir, grand fir, and Rhododendron x ?Nova Zembla? foliage from P. ramorum was tested. The tops of conifer seedlings with newly emerging shoots and mature rhododendron leaves were collected from treated plants 7 days after drench applications or 1 day after foliar applications....

  12. The effect of relative humidity on germination of Sporangia of Phytophthora ramorum

    USDA-ARS?s Scientific Manuscript database

    Sporangia of three isolates of P. ramorum representing three different clonal lineages were subjected to relative humidity (RH) levels between 80 and 100% for exposure periods ranging from 1 to 24 h at 20°C in darkness. Airtight snap-lid plastic containers (21.5 x 14.5 x 5 cm) were used as humidity ...

  13. Population dynamics of aerial and terrestrial populations of Phytophthora ramorum in a California forest under different climatic conditions.

    PubMed

    Eyre, C A; Kozanitas, M; Garbelotto, M

    2013-11-01

    Limited information is available on how soil and leaf populations of the sudden oak death pathogen, Phytophthora ramorum, may differ in their response to changing weather conditions, and their corresponding role in initiating the next disease cycle after unfavorable weather conditions. We sampled and cultured from 425 trees in six sites, three times at the end of a 3-year-long drought and twice during a wet year that followed. Soil was also sampled twice with similar frequency and design used for sampling leaves. Ten microsatellites were used for genetic analyses on cultures from successful isolations. Results demonstrated that incidence of leaf infection tripled at the onset of the first wet period in 3 years in spring 2010, while that of soil populations remained unchanged. Migration of genotypes among sites was low and spatially limited under dry periods but intensity and range of migration of genotypes significantly increased for leaf populations during wet periods. Only leaf genotypes persisted significantly between years, and genotypes present in different substrates distributed differently in soil and leaves. We conclude that epidemics start rapidly at the onset of favorable climatic conditions through highly transmissible leaf genotypes, and that soil populations are transient and may be less epidemiologically relevant than previously thought.

  14. New technologies to detect and monitor Phytophthora ramorum in plant, soil, and water samples

    Treesearch

    Paul Russell; Nathan McOwen; Robert Bohannon

    2013-01-01

    The focus of our research efforts has been to develop methods to quickly identify plants, soil, and water samples infested with Phytophthora spp., and to rapidly confirm the findings using novel isothermal DNA technologies suitable for field use. These efforts have led to the development of a rapid Immunostrip® that reliably detects...

  15. Effect of flooding on root and foliar disease severity on Rhododendron Caused by Phytophthora ramorum

    Treesearch

    Niklaus J. Grünwald; Megan Kitner; Robert G. Linderman

    2008-01-01

    It is generally thought that extensive periods of flooding can predispose plants to infection by Phytophthora pathogens. We evaluated the effect of 0, 1, 3, and 7 days of flooding before infection of Rhododendron plants through either wound inoculation of leaves or infestation of the potting mix using two hybrid cultivars ?...

  16. Effect of plant sterols and tannins on Phytophthora ramorum growth and sporulation

    Treesearch

    Rachel A. Stong; Eli Kolodny; Rick G. Kelsey; M.P. Gonzalez-Hernandez; Jorge M. Vivanco; Daniel K. Manter

    2013-01-01

    Elicitin-mediated acquisition of plant sterols is required for growth and sporulation of Phytophthora spp. This study examined the interactions between elicitins, sterols, and tannins. Ground leaf tissue, sterols, and tannin-enriched extracts were obtained from three different plant species (California bay laurel, California black oak, and Oregon...

  17. Photosynthetic declines are induced by Phytophthora ramorum infection and exposure to elicitins

    Treesearch

    Daniel K. Manter; Rick G. Kelsey; Joseph J. Karchesy

    2008-01-01

    Infection of compatible plants by Phytophthora spp. often leads to a decline in stomatal conductance and photosynthesis, although the mechanistic basis for such declines is not completely understood. In many cases, declines in leaf gas exchange rates have been linked to losses in water supply capacity associated with root and/or xylem. However, the...

  18. The effect of temperature on germination of chlamydospores of Phytophthora ramorum.

    PubMed

    Tooley, Paul W; Browning, Marsha; Leighty, Robert M

    2014-01-01

    Mycelium-free chlamydospores of 12 isolates of P. ramorum representing three clonal lineages were produced with a method involving incubation in nonsterile sand at 20 C in darkness for 30 d. Chlamydospores were incubated on selective agar medium at 5, 10, 15, 20, 25 and 30 C and germination assessed after 1, 2, 4, 6 and 8 d incubation. The optimal temperature for germination based on 8 d incubation was 20 C for all three clonal lineages tested (NA1, NA2, EU1). Mean germination rates were 2, 21, 44, 67, 32 and 0 percent at 5, 10, 15, 20, 25 and 30 C respectively for all isolates combined. The highest mean germination rate was scored by isolates of the EU1 clonal lineage at 20 C (85%) after 8 d incubation However, substantial variation was observed among isolates within each clonal lineage. Overall temperatures and days of incubation on which germination was assessed isolates of the NA1 clonal lineage had the lowest mean germination, even though one isolate had the highest germination of any isolate in any lineage. The results indicate that 20 C is the optimal germination temperature for P. ramorum chlamydospores and that a great disparity in germination percentage can exist within isolates, even within a single clonal lineage.

  19. Genome sequences of 12 isolates of the EU1 lineage of Phytophthora ramorum, a fungus-like pathogen that causes extensive damage and mortality to a wide range of trees and other plants.

    PubMed

    Turner, Judith; O'Neill, Paul; Grant, Murray; Mumford, Rick A; Thwaites, Richard; Studholme, David J

    2017-06-01

    Here we present genome sequences for twelve isolates of the invasive pathogen Phytophthora ramorum EU1. The assembled genome sequences and raw sequence data are available via BioProject accession number PRJNA177509. These data will be useful in developing molecular tools for specific detection and identification of this pathogen.

  20. Phylogenetic relationships of Phytophthora ramorum, P. nemorosa, and P. pseudosyringae, three species recovered from areas in California with sudden oak death.

    PubMed

    Martin, Frank N; Tooley, Paul W

    2003-12-01

    Sudden oak death has been an emerging disease problem in coastal California and has caused significant losses in forest ecosystems in some regions of the state. The causal agent of this disease has been described as Phytophthora ramorum with two other less aggressive species, P. nemorosa and P. pseudosyringae, recovered from some symptomatic plants. The phylogenetic relationship of these species with other members of the genus was examined by sequence alignment of 667 bp of the mitochondrially-encoded cytochrome oxidase II gene and the nuclear encoded rDNA internal transcribed spacer region. P. ramorum was most closely related to P. hibernalis and P. lateralis in trees from both regions, although the specific relationship among species differed depending on the tree. In the cox II tree these species were on a single clade with P. lateralis basal to a group containing P. ramorum and P. hibernalis. On the maximum parsimony ITS tree P. ramorum was most closely affiliated with P. lateralis and in the same clade as P. hibernalis, but with maximum likelihood analysis P. ramorum was basal to a grouping of P. hibernalis and P. lateralis. While bootstrap support was strong for the grouping of these species together, it was not for determining the relationship among them. In contrast to the cox II tree, the clade containing these three species grouped with P. cryptogea, P. drechsleri, P. erythroseptica, and P. syringae in the ITS tree. Since the same isolates of these species were used for both the cox II and ITS sequence analysis, this difference in species grouping suggests either a differential rate of evolutionary divergence for these two regions, incorrect assumptions about alignment of ITS sequences, or different evolutionary histories of the regions under study. Analysis of combined cox II and ITS data sets gave trees where the relationships among these species were the same as for the ITS tree alone, although the results of the partition homogeneity test (P=0

  1. Global gene expression profiles of Phytophthora ramorum strain pr102 in response to plant host and tissue differentiation

    Treesearch

    Caroline M. Press; Niklaus J. Grunwald

    2008-01-01

    The release of the draft genome sequence of P. ramorum strain Pr102, enabled the construction of an oligonucleotide microarray of the entire genome of Pr102. The array contains 344,680 features (oligos) that represent the transcriptome of Pr102. P. ramorum RNA was extracted from mycelium and sporangia and used to compare gene...

  2. Identification of Quercus agrifolia (coast live oak) resistant to the invasive pathogen Phytophthora ramorum in native stands using Fourier-transform infrared (FT-IR) spectroscopy.

    PubMed

    Conrad, Anna O; Rodriguez-Saona, Luis E; McPherson, Brice A; Wood, David L; Bonello, Pierluigi

    2014-01-01

    Over the last two decades coast live oak (CLO) dominance in many California coastal ecosystems has been threatened by the alien invasive pathogen Phytophthora ramorum, the causal agent of sudden oak death. In spite of high infection and mortality rates in some areas, the presence of apparently resistant trees has been observed, including trees that become infected but recover over time. However, identifying resistant trees based on recovery alone can take many years. The objective of this study was to determine if Fourier-transform infrared (FT-IR) spectroscopy, a chemical fingerprinting technique, can be used to identify CLO resistant to P. ramorum prior to infection. Soft independent modeling of class analogy identified spectral regions that differed between resistant and susceptible trees. Regions most useful for discrimination were associated with carbonyl group vibrations. Additionally, concentrations of two putative phenolic biomarkers of resistance were predicted using partial least squares regression; >99% of the variation was explained by this analysis. This study demonstrates that chemical fingerprinting can be used to identify resistance in a natural population of forest trees prior to infection with a pathogen. FT-IR spectroscopy may be a useful approach for managing forests impacted by sudden oak death, as well as in other situations where emerging or existing forest pests and diseases are of concern.

  3. Identification of Quercus agrifolia (coast live oak) resistant to the invasive pathogen Phytophthora ramorum in native stands using Fourier-transform infrared (FT-IR) spectroscopy

    PubMed Central

    Conrad, Anna O.; Rodriguez-Saona, Luis E.; McPherson, Brice A.; Wood, David L.; Bonello, Pierluigi

    2014-01-01

    Over the last two decades coast live oak (CLO) dominance in many California coastal ecosystems has been threatened by the alien invasive pathogen Phytophthora ramorum, the causal agent of sudden oak death. In spite of high infection and mortality rates in some areas, the presence of apparently resistant trees has been observed, including trees that become infected but recover over time. However, identifying resistant trees based on recovery alone can take many years. The objective of this study was to determine if Fourier-transform infrared (FT-IR) spectroscopy, a chemical fingerprinting technique, can be used to identify CLO resistant to P. ramorum prior to infection. Soft independent modeling of class analogy identified spectral regions that differed between resistant and susceptible trees. Regions most useful for discrimination were associated with carbonyl group vibrations. Additionally, concentrations of two putative phenolic biomarkers of resistance were predicted using partial least squares regression; >99% of the variation was explained by this analysis. This study demonstrates that chemical fingerprinting can be used to identify resistance in a natural population of forest trees prior to infection with a pathogen. FT-IR spectroscopy may be a useful approach for managing forests impacted by sudden oak death, as well as in other situations where emerging or existing forest pests and diseases are of concern. PMID:25352852

  4. AFLP analysis of Phytophthora nemorosa and P. pseudosyringae genetic structure in North America

    Treesearch

    Rachel Linzer; David Rizzo; Matteo Garbelotto

    2006-01-01

    In California and Oregon, Phytophthora ramorum has an overlapping host and geographic range with two newly described homothallic Phytophthora species, P. nemorosa and P. pseudosyringae. P. nemorosa alone causes symptoms similar to those of P. ramorum,...

  5. Diversity of foliar Phytophthora species on Rhododendron in Oregon nurseries

    Treesearch

    B.J. Knaus; K.A. Graham; Niklaus J. Grünwald; Valerie J. Fieland

    2017-01-01

    The genus Phytophthora contains some of the most notorious plant pathogens affecting nursery crops. Given the recent emergence of the sudden oak death pathogen Phytophthora ramorum, particularly in association with Rhododendron spp., characterization of Phytophthora communities...

  6. Pilot program (proof of concept) to mitigate Phytophthora ramorum at an infested nursery based on a systems approach

    Treesearch

    Gary Chastagner; Marianne Elliott

    2017-01-01

    The primary purpose of this program was to demonstrate proof of concept of certain mitigation approaches at a repeat P. ramorum-positive nursery site in Washington. Approaches included steam treatment of infested soil areas; creating a gravel “sandwich” above steam-treated and potentially infested soil surfaces; improving drainage systems; required...

  7. The effect of temperature and moisture period on infection of Rhododendron Cunningham’s White by Phytophthora ramorum

    USDA-ARS?s Scientific Manuscript database

    We investigated the temperature and moisture conditions that allow P. ramorum to infect 'Cunningham's White' rhododendron. For whole plants incubated in dew chambers at 10-31C, the greatest percentage diseased leaves occurred at 22C, followed by 16, 25, and 19C. Significantly less infection occur...

  8. Development of a predictive model to estimate the effect of soil solarization on survival of soilborne inoculum of Phytophthora ramorum and Phytophthora pini

    Treesearch

    Fumiaki Funahashi; Jennifer L. Parke

    2017-01-01

    Soil solarization has been shown to be an effective tool to manage Phytophthora spp. within surface soils, but estimating the minimum time required to complete local eradication under variable weather conditions remains unknown. A mathematical model could help predict the effectiveness of solarization at different sites and soil depths....

  9. Knowing your Phytophthora

    USDA-ARS?s Scientific Manuscript database

    Phytophthora pathogens are known as some of the most important plant killers known to man. Two particularly notorious killers include the Irish potato famine pathogen P. infestans affecting potato and tomato and the sudden oak death P. ramorum affecting woody ornamentals and trees. Phytophthora path...

  10. Probabilistic commodity-flow-based focusing of monitoring activities to facilitate early detection of Phytophthora ramorum outbreaks

    Treesearch

    Steven C. McKelvey; William D. Smith; Frank Koch

    2012-01-01

    This project summary describes a probabilistic model developed with funding support from the Forest Health Monitoring Program of the Forest Service, U.S. Department of Agriculture (BaseEM Project SO-R-08-01). The model has been implemented in SODBuster, a standalone software package developed using the Java software development kit from Sun Microsystems.

  11. Pathogenicity variation in two west coast forest Phytophthoras, Phytophthora nemorosa and P. pseudosyringae, to bay laurel

    Treesearch

    R.E. Linzer; M. Garbelotto

    2008-01-01

    Two recently described pathogenic oomycetes, Phytophthora nemorosa and P. pseudosyringae, have overlapping host and geographic ranges in California and Oregon forests with P. ramorum, causal agent of ?sudden oak death? disease. Preliminary genetic evidence indicates P. nemorosa and P....

  12. Ecology of Phytophthora nemorosa and Phytophthora pseudosyringae in mixed-evergreen forests

    Treesearch

    Allison C. Wickland; David M. Rizzo

    2006-01-01

    Recent research has shown that Phytophthora ramorum is a major threat to California’s coast live oak (Quercus agrifolia) dominated, mixed-evergreen forests (Rizzo and Garbelotto 2003). However, the role that diseases caused by other Phytophthora species play in the ecology of these forest communities is less...

  13. Some challenges of recognizing invasive phytophthoras and finding their origins

    Treesearch

    Everett Hansen

    2010-01-01

    Discovering the origins of Phytophthora ramorum remains a challenge. To improve our chances of finding the origin of P. ramorum or any other introduced organism, we need to be sure of our motivation, because success will require persistence. We need to be able to distinguish indigenous from exotic organisms, to know what to...

  14. Phytophthora siskiyouensis, a new species from soil and water in southwest Oregon

    Treesearch

    Paul Reeser; Everett Hansen; Wendy Sutton

    2008-01-01

    An unknown Phytophthora species was recovered from rhododendron and tanoak leaf baits used for monitoring streams and soils in Southwestern Oregon for the presence of Phytophthora ramorum. Isolates of this species yielded ITS-DNA sequences that differed substantially from other Phytophthora sequences in GenBank....

  15. Evaluation of chemical and biological agents for control of Phytophthora species on intact plants or detached leaves of rhododendron and lilac

    Treesearch

    R.G. Linderman; E.A. Davis

    2006-01-01

    The recent incidence of Ramorum blight, caused by Phytophthora ramorum, on many nursery crops has focused attention on improving management strategies against Phytophthora diseases in nurseries. We evaluated several chemical agents that target Oomycete pathogens for their capacity to inhibit infection of rhododendron or lilac...

  16. Dissemination of aerial and root infecting Phytophthoras by human vectors

    Treesearch

    J.F. Webber; J. Rose

    2008-01-01

    Two new Phytophthora pathogens, Phytophthora kernoviae and P. ramorum, have recently established in parts of the U.K. They are most prevalent in the south west of England where they cause intense episodes of foliar blight and dieback on both ornamental and naturalised rhododendron such as Rhododendron ponticum,...

  17. Combining field epidemiological information and genetic data to comprehensively reconstruct the invasion history and the microevolution of the sudden oak death agent Phytophthora ramorum (Stramenopila: Oomycetes) in California.

    PubMed

    Croucher, Peter J P; Mascheretti, Silvia; Garbelotto, Matteo

    2013-01-01

    Understanding the migration patterns of invasive organisms is of paramount importance to predict and prevent their further spread. Previous attempts at reconstructing the entire history of the sudden oak death (SOD) epidemic in California were limited by: (1) incomplete sampling; (2) the inability to include infestations caused by a single genotype of the pathogen; (3) collapsing of non-spatially contiguous yet genetically similar samples into large meta-samples that confounded the coalescent analyses. Here, we employ an intensive sampling coverage of 832 isolates of Phytopthora ramorum (the causative agent of SOD) from 60 California forests, genotyped at nine microsatellite loci, to reconstruct its invasion. By using age of infestation as a constraint on coalescent analyses, by dividing genetically indistinguishable meta-populations into highly-resolved sets of spatially contiguous populations, and by using Bruvo genetic distances for most analyses, we reconstruct the entire history of the epidemic and convincingly show infected nursery plants are the original source for the entire California epidemic. Results indicate that multiple human-mediated introductions occurred in most counties and that further disease sources were represented by large wild infestations. The study also identifies minor introductions, some of them relatively recent, linked to infected ornamental plants. Finally, using archival isolates collected soon after the discovery of the pathogen in California, we corroborate that the epidemic is likely to have resulted form 3 to 4 core founder individuals evolved from a single genotype. This is probably the most complete reconstruction ever completed for an invasion by an exotic forest pathogen, and the approach here described may be useful for the reconstruction of invasions by any clonally reproducing organism with a relatively limited natural dispersal range.

  18. Phytophthora Genome Sequences Uncover Evolutionary Origins and Mechanisms of Pathogenesis

    SciTech Connect

    Lamour, Kurt H; McDonald, W Hayes; Savidor, Alon

    2006-01-01

    Genome sequences of the soybean pathogen, Phytophthora sojae, and the sudden oak death pathogen, Phytophthora ramorum, suggest a photosynthetic past and reveal recent massive expansion and diversification of potential pathogenicity gene families. Abstract: Draft genome sequences of the soybean pathogen, Phytophthora sojae, and the sudden oak death pathogen, Phytophthora ramorum, have been determined. O mycetes such as these Phytophthora species share the kingdom Stramenopila with photosynthetic algae such as diatoms and the presence of many Phytophthora genes of probable phototroph origin support a photosynthetic ancestry for the stramenopiles. Comparison of the two species' genomes reveals a rapid expansion and diversification of many protein families associated with plant infection such as hydrolases, ABC transporters, protein toxins, proteinase inhibitors and, in particular, a superfamily of 700 proteins with similarity to known o mycete avirulence genes.

  19. Phytophthora austrocedrae.

    Treesearch

    A. Greslebin; E. M. Hansen; L. La Manna

    2011-01-01

    Phytophthora austrocedrae Gresl. & E.M. Hansen (2007) was isolated from necrotic lesions of stem and roots of Austrocedrus chilensis (Cupressaceae). It is homothallic with semi-papillate sporangia, oogonia with amphigynous antheridia, and very slow growth. It is the cause of "mal del...

  20. Phytophthora siskiyouensis

    Treesearch

    E. M. Hansen; P. Reeser; S. Rooney-Latham

    2011-01-01

    Phytophthora siskiyouensis Reeser & E.M. Hansen (2007) was discovered first in streams and soil in Curry County, Oregon in areas dominated by native forest, and most isolates continue to come from these sources. Only later, and still infrequently, were isolates of the new species recovered from diseased forest plants. Recent...

  1. Monitoring occurrence and distribution of Phytophthora species in forest streams in North Carolina using bait and filtration methods

    Treesearch

    Jaesoon Hwang; S.W. Oak; S.N. Jeffers

    2009-01-01

    The recent epidemics of sudden oak death, caused by Phytophthora ramorum, in the coastal forests of California and southwest Oregon have drawn attention to other species of Phytophthora present in natural ecosystems that may threaten forest tree health. Since Phytophthora species are well adapted to aquatic...

  2. AFLPs detect low genetic diversity for Phytophthora nemorosa and P. pseudosyringae in the US and Europe

    Treesearch

    Rachel E. Linzer; David M. Rizzo; Santa Olga Cacciola; Matteo Garbelotto

    2009-01-01

    In California and Oregon, two recently described oomycete forest pathogens, Phytophthora nemorosa and P. pseudosyringae, overlap in their host and geographic ranges with the virulent P. ramorum, causal agent of "sudden oak death." Epidemiological observations, namely broader geographic...

  3. Histopathological investigations of the infection process and propagule development of Phytophthora ramorumon rhododendron leaves

    Treesearch

    Marko Riedel; Sabine Werres; Marianne Elliott; Katie McKeever; Simon Shamoun

    2012-01-01

    Studies on the relationship between rhododendron and Phytophthora ramorum include the influence of wounds on leaf infection and on the development of leaf necrosis (De Dobbelaere et al. 2010; Denman et al. 2005), the influence of the inoculum type (Widmer 2009), and tissue colonization by P. ramorum (Brown and Brasier 2007;...

  4. Phytopthora ramorum in Belgium: 2002 survey results and research efforts.

    PubMed

    Heungens, K; Crepel, C; Inghelbrecht, S; Maes, M

    2003-01-01

    Phytophthora ramorum is a new and aggressive Phytophthora species that causes leaf blight and dieback symptoms on Viburnum and Rhododendron plants in Europe. A variant of this fungus is responsible for Sudden Oak Death (SOD) in California and Oregon. In Europe, problems so far are mostly restricted to nursery plants of Rhododendron and Viburnum while in the US, the fungus has been isolated from over 20 host species and is responsible for massive killing of oak trees (mostly Quercus agrifolia and Lithocarpus densiflorus) in forest and park settings. The potential for infection of native tree species in Europe and the recent detection of the fungus in nurseries of several European countries has lead to the implementation of EU emergency phytosanitary measures. As a result, most European countries have conducted surveys and are doing research as part of risk assessment efforts. The first part of this paper focuses on the plant diagnoses of the 2002 survey of P. ramorum in Belgian nurseries. The data from the survey indicates P. ramorum is present in Belgium at similar rates as in the neighbouring countries, in an apparent random distribution. The second part of this paper describes research results relating to the in vitro effect of oomycete fungicides on P. ramorum, Rhododendron cultivar susceptibility, the determination of the leaf infection site, and pathogen survival. Some fungicides had excellent in vitro activity against P. ramorum and should be tested further on plants. Use of host resistance as a control strategy may be limited as little difference in cultivar sensitivity was observed. Infection studies showed that wounds and the lower sides of the leaves are most susceptible to infection. Once the pathogen gets inside, it can survive well on detached leaves, especially when they are kept cool and moist. These data can contribute to management decisions of P. ramorum at the level of nurseries as well as the government.

  5. Phytophthora Genome Sequences Uncover Evolutionary Origins and Mechanisms of Pathogenesis

    SciTech Connect

    Tyler, Brett M.; Tripathy, Sucheta; Zhang, Xuemin; Dehal, Paramvir; Jiang, Rays H. Y.; Aerts, Andrea; Arredondo, Felipe D.; Baxter, Laura; Bensasson, Douda; Beynon, JIm L.; Chapman, Jarrod; Damasceno, Cynthia M. B.; Dorrance, Anne E.; Dou, Daolong; Dickerman, Allan W.; Dubchak, Inna L.; Garbelotto, Matteo; Gijzen, Mark; Gordon, Stuart G.; Govers, Francine; Grunwald, NIklaus J.; Huang, Wayne; Ivors, Kelly L.; Jones, Richard W.; Kamoun, Sophien; Krampis, Konstantinos; Lamour, Kurt H.; Lee, Mi-Kyung; McDonald, W. Hayes; Medina, Monica; Meijer, Harold J. G.; Nordberg, Erik K.; Maclean, Donald J.; Ospina-Giraldo, Manuel D.; Morris, Paul F.; Phuntumart, Vipaporn; Putnam, Nicholas J.; Rash, Sam; Rose, Jocelyn K. C.; Sakihama, Yasuko; Salamov, Asaf A.; Savidor, Alon; Scheuring, Chantel F.; Smith, Brian M.; Sobral, Bruno W. S.; Terry, Astrid; Torto-Alalibo, Trudy A.; Win, Joe; Xu, Zhanyou; Zhang, Hongbin; Grigoriev, Igor V.; Rokhsar, Daniel S.; Boore, Jeffrey L.

    2006-04-17

    Draft genome sequences have been determined for the soybean pathogen Phytophthora sojae and the sudden oak death pathogen Phytophthora ramorum. Oömycetes such as these Phytophthora species share the kingdom Stramenopila with photosynthetic algae such as diatoms, and the presence of many Phytophthora genes of probable phototroph origin supports a photosynthetic ancestry for the stramenopiles. Comparison of the two species' genomes reveals a rapid expansion and diversification of many protein families associated with plant infection such as hydrolases, ABC transporters, protein toxins, proteinase inhibitors, and, in particular, a superfamily of 700 proteins with similarity to known oömycete avirulence genes.

  6. Variation in density and diversity of species of Phytophthora in two forest stream networks

    Treesearch

    Jaesoon Hwang; Steven N. Jeffers; Steven W. Oak

    2010-01-01

    Monitoring occurrence and distribution of Phytophthora species, including Phytophthora ramorum, in forest ecosystems can be achieved in several ways including sampling symptomatic plants, infested soils, and infested streams. Collecting plant and soil samples can be laborious and time consuming due to the distance surveyors...

  7. Infectivity and sporulation potential of Phytophthora kernoviae to select North American native plants

    Treesearch

    E. J. Fichtner; D. M. Rizzo; S. A. Kirk; J. F. Webber

    2011-01-01

    Phytophthora kernoviae exhibits comparable epidemiology to Phytophthora ramorum in invaded UK woodlands. Because both pathogens have an overlapping geographic range in the UK and often concurrently invade the same site, it is speculated that P. kernoviae may also invade North American (NA) forests...

  8. Identification and frequency of Phytophthora species associated with foliar diseases in California ornamental nurseries

    Treesearch

    L. E. Yakabe; C. L. Blomquist; S. L. Thomas; J. D. MacDonald

    2009-01-01

    Numerous ornamental nurseries in 32 California counties were surveyed for leaf spots as part of the California Department of Food and Agriculture mandated surveys targeting Phytophthora ramorum. Tissue collected during the 2005 and 2006 surveys was initially screened by a Phytophthora-specific enzyme-linked immunosorbent assay...

  9. Population genetic analysis of four Phytophthoras recently described in California reveal they are all introduced

    Treesearch

    M. Garbelotto; R. Linzer; W. Monahan; S. Bergeman

    2009-01-01

    Four Phytophthora species have recently been described in California natural ecosystems: Phytophthora ramorum, P. ilicis, P. pseudosyringae, and P. cinnamomi. The first three species are of recent description, while the last one is a well-known pathogen associated with agricultural crops in the Western USA...

  10. Phytophthora species from oak and tanoak forests in California and Oregon

    Treesearch

    Everett Hansen; David Rizzo; Matteo Garbelotto

    2006-01-01

    The current sudden oak death (SOD) epidemics in Europe and western North America triggered a search of North American oak forests for other Phytophthora species, and the results from the western United States have been surprising. Phytophthora ramorum has been the main quarry, and as an aerial pathogen, it is a surprise in itself....

  11. Microbial- and isothiocyanate-mediated control of Phytophthora and Pythium species

    Treesearch

    M.F. Cohen; E. Yamamoto; E. Condeso; B.L. Anacker; N. Rank; M. Mazzola

    2008-01-01

    Plant pathogens of the oomycete lineage share common susceptibilities to many biotic and abiotic stresses. We are investigating the potential of antagonistic bacteria, isothiocyanates, and mycophagous amoebae to control diseases caused by Phytophthora spp., including the etiologic agent of sudden oak death, Phytophthora ramorum (...

  12. Population genetic analysis reveals ancient evolution and recent migration of P. ramorum

    Treesearch

    Erica M. Goss; Meg Larsen; Ignazio Carbone; Donald R. Givens; Gary A. Chastagner; Niklaus J. Gr& uuml; nwald

    2010-01-01

    Phytophthora ramorum populations in North America and Europe are comprised of three clonal lineages based on several different genetic marker systems (Ivors and others 2006, Martin 2008). Whether these lineages are ancient or a recent artifact of introduction has been unclear. We analyzed DNA sequence variation at five nuclear loci in order to...

  13. Development and Validation of a Tissue based Panel for the P. ramorum Proficiency Testing Program

    USDA-ARS?s Scientific Manuscript database

    Proficiency testing (PT) is a key element of a laboratory accreditation program. A tissue-based PT panel for the Sudden Oak Death pathogen, Phytophthora ramorum, used by the National Plant Protection Laboratory Accreditation Program (NPPLAP), was developed and validated in 2008 to assess proficienc...

  14. Spread of P. ramorum from nurseries into waterways-implications for pathogen establishment in new areas

    Treesearch

    Gary Chastagner; Steven Oak; Daniel Omdal; Amy Ramsey-Kroll; Katie Coats; Yana Valachovic; Chris Lee; Jaesoon Hwang; Steven Jeffers; Marianne. Elliott

    2010-01-01

    In the United States, water and soil baiting have been part of the U.S. Department of Agriculture, Animal and Plant Health Inspection Service (USDA APHIS) Confirmed Nursery Protocol (CNP) to prevent the spread of Phytophthora ramorum from infected nursery stock since 2005. Additionally, the U.S. Department of Agriculture, Forest Service (USDA...

  15. California bay laurel susceptibility to Phythophthora ramorum depends upon season, leaf age, and fungal load

    Treesearch

    Steve Johnston; Nathan Rank; Michael Cohen; Ross Meentemeyer

    2010-01-01

    Phytophthora ramorum can produce spores on dozens of native California plant species, but the most important vector for infection of oak (Quercus) is California bay laurel (Umbellularia californica). Presence of bay laurel is associated with increased infection of oaks and it is the most common tree...

  16. Managing Phytophthora ramorum at Bloedel Reserve

    Treesearch

    Darren Strenge; Marianne Elliott; Gary Chastagner; Casey Sclar

    2017-01-01

    Bloedel Reserve is a 150-acre botanical garden and nature preserve on the north end of Bainbridge Island in Washington on the Puget Sound. The grounds encompass undeveloped forest, pastures, a bird marsh, woodland plantings, and intensely maintained gardens within the limits of the City of Bainbridge Island. The garden is part of the Sentinel Plant Network, a...

  17. Methods for assessing Phytophthora ramorum chlamydospore germination

    Treesearch

    Joyce Eberhart; Elilzabeth Stamm; Jennifer Parke

    2013-01-01

    Germination of chlamydospores is difficult to accurately assess when chlamydospores are attached to remnants of supporting hyphae. We developed two approaches for closely observing and rigorously quantifying the frequency of chlamydospore germination in vitro. The plate marking and scanning method was useful for quantifying germination of large...

  18. Rhododendron leaf baiting of coastal California watersheds for Phytophthora

    Treesearch

    Tyler B. Bourret; Heather K. Mehl; Kamyar Aram; David M. Rizzo

    2017-01-01

    For more than a decade, the Rizzo lab and collaborators have monitored northern and central coastal California watersheds each spring and early summer for the presence of Phytophthora using submerged Rhododendron leaves as bait. This served as an early detection tool for the sudden oak death (SOD) pathogen, P. ramorum...

  19. Root infections may challenge management of invasive Phytophthora spp

    Treesearch

    E.J. Fichtner; D.M. Rizzo; S.A. Kirk; J.F. Webber

    2011-01-01

    Because sporulation of Phytophthora ramorum and P. kernoviae on Rhododendron ponticum, an invasive plant, serves as primary inoculum for trunk infections on trees, R. ponticum clearance from pathogen-infested woodlands is pivotal to inoculum management. The efficacy of clearance for...

  20. Phytophthora species associated with tanoak stem cankers in southwestern Oregon

    Treesearch

    Paul Reeser; Wendy Sutton; Everett Hansen

    2009-01-01

    From 2001 through 2006 stem cankers on tanoak (Lithocarpus densiflorus) were sampled during surveys to detect and eradicate Phytophthora ramorum from forests in southwestern Oregon. Pieces of bark from stem canker margins were plated on cornmeal agar amended with 10 ppm natamycin, 200 ppm Na-ampicillin, and 10 ppm rifampicin....

  1. Phytophthora species in tanoak trees, canopy-drip, soil, and streams in the sudden oak death epidemic area of south-western Oregon, USA

    Treesearch

    Paul Reeser; Wendy Sutton; Everett Hansen.

    2011-01-01

    Various Phytophthora species were recovered from tanoak trees, tanoak canopy drip, soils, and streams, which were sampled as part of a larger survey and management effort aimed at limiting the spread of Phytophthora ramorum Werres, De Cock & Man in't Veld (the causal agent of sudden oak death) in an epidemic area...

  2. Mapping hardwood mortality for the early detection of P. ramorum: an assessment of aerial surveys and object-oriented image analysis

    Treesearch

    Erik Haunreiter; Zhanfeng Liu; Jeff Mai; Zachary Heath; Lisa Fischer

    2008-01-01

    Effective monitoring and identification of areas of hardwood mortality is a critical component in the management of sudden oak death (SOD). From 2001 to 2005, aerial surveys covering 13.5 million acres in California were conducted to map and monitor hardwood mortality for the early detection of Phytophthora ramorum, the pathogen responsible for SOD....

  3. Phytophthora species associated with stem cankers on tanoak in southwestern Oregon

    Treesearch

    Paul Reeser; Wendy Sutton; Everett Hansen

    2008-01-01

    In effort to eradicate Phytophthora ramorum from Oregon forests, tanoak over its entire range in southwestern Oregon is surveyed intensively for stem disease. Pieces of bark from the leading edge of tanoak stem cankers were plated on cornmeal agar amended with 10 ppm natamycin, 200 ppm a-ampicillin, and 10 ppm rifamycin SV (CARP) to favor the...

  4. Genome sequences of Phytophthora enable translational plant disease management and accelerate research

    Treesearch

    Niklaus J. Grünwald

    2012-01-01

    Whole and partial genome sequences are becoming available at an ever-increasing pace. For many plant pathogen systems, we are moving into the era of genome resequencing. The first Phytophthora genomes, P. ramorum and P. sojae, became available in 2004, followed shortly by P. infestans...

  5. Phytophthora species associated with forest soils in central and eastern U.S. oak ecosystems

    Treesearch

    Y. Balci; S. Balci; J. Eggers; W.L. MacDonald; K.W. Gottschalk; J. Juzwik; R. Long

    2006-01-01

    The existence of native and exotic species of Phytophthora in soils of eastern and central oak ecosystems is largely unknown. This informational void and the potential threat of P. ramorum to eastern oak species provided the impetus for a multiple state survey of soils associated with oak cover types. The initial survey was...

  6. Genome sequences of Phytophthora enable translational plant disease management and accelerate research

    USDA-ARS?s Scientific Manuscript database

    Whole and partial genome sequences are becoming available at an ever-increasing pace. For many plant pathogen systems, we are moving into the era of genome resequencing. The first Phytophthora genomes, P. ramorum and P. sojae, became available in 2004, followed shortly by P. infestans in 2006. Ava...

  7. A systems approach for detecting sources of Phytophthora contamination in nurseries

    Treesearch

    Jennifer L. Parke; Niklaus Grünwald; Carrie Lewis; Val Fieland

    2010-01-01

    Nursery plants are also important long-distance vectors of non-indigenous pathogens such as P. ramorum and P. kernoviae. Pre-shipment inspections have not been adequate to ensure that shipped plants are free from Phytophthora, nor has this method informed growers about sources of contamination in their...

  8. Gene duplication event in family 12 glycosyl hydrolase from Phytophthora spp.

    PubMed

    Costanzo, Stefano; Ospina-Giraldo, M D; Deahl, K L; Baker, C J; Jones, Richard W

    2006-10-01

    A total of 18 paralogs of xyloglucan-specific endoglucanases (EGLs) from the glycosyl hydrolase family 12 were identified and characterized in Phytophthora sojae and Phytophthora ramorum. These genes encode predicted extracellular enzymes, with sizes ranging from 189 to 435 amino acid residues, that would be capable of hydrolyzing the xyloglucan component of the host cell wall. In two cases, four and six functional copies of these genes were found in tight succession within a region of 5 and 18 kb, respectively. The overall gene copy number and relative organization appeared well conserved between P. sojae and P. ramorum, with apparent synteny in this region of their respective genomes. Phylogenetic analyses of Phytophthora endoglucanases of family 12 and other known members of EGL 12, revealed a close relatedness with a fairly conserved gene sub-family containing, among others, sequences from the fungi Emericella desertorum and Aspergillus aculeatus. This is the first report of family 12 EGLs present in plant pathogenic eukaryotes.

  9. Phytophthora lateralis.

    Treesearch

    E.M. Hansen

    2011-01-01

    Phytophthora lateralis was named by Tucker and Milbrath in 1942. There are no known synonyms. P. lateralis was classified in morphological group V by Stamps et al. (1990); the group includes homothallic species with paragynous antheridia and nonpapillate, proliferating sporangia.

  10. Ancient origin of elicitin gene clusters in Phytophthora genomes.

    PubMed

    Jiang, Rays H Y; Tyler, Brett M; Whisson, Stephen C; Hardham, Adrienne R; Govers, Francine

    2006-02-01

    The genus Phytophthora belongs to the oomycetes in the eukaryotic stramenopile lineage and is comprised of over 65 species that are all destructive plant pathogens on a wide range of dicotyledons. Phytophthora produces elicitins (ELIs), a group of extracellular elicitor proteins that cause a hypersensitive response in tobacco. Database mining revealed several new classes of elicitin-like (ELL) sequences with diverse elicitin domains in Phytophthora infestans, Phytophthora sojae, Phytophthora brassicae, and Phytophthora ramorum. ELIs and ELLs were shown to be unique to Phytophthora and Pythium species. They are ubiquitous among Phytophthora species and belong to one of the most highly conserved and complex protein families in the Phytophthora genus. Phylogeny construction with elicitin domains derived from 156 ELIs and ELLs showed that most of the diversified family members existed prior to divergence of Phytophthora species from a common ancestor. Analysis to discriminate diversifying and purifying selection showed that all 17 ELI and ELL clades are under purifying selection. Within highly similar ELI groups there was no evidence for positively selected amino acids suggesting that purifying selection contributes to the continued existence of this diverse protein family. Characteristic cysteine spacing patterns were found for each phylogenetic clade. Except for the canonical clade ELI-1, ELIs and ELLs possess C-terminal domains of variable length, many of which have a high threonine, serine, or proline content suggesting an association with the cell wall. In addition, some ELIs and ELLs have a predicted glycosylphosphatidylinositol site suggesting anchoring of the C-terminal domain to the cell membrane. The eli and ell genes belonging to different clades are clustered in the genomes. Overall, eli and ell genes are expressed at different levels and in different life cycle stages but those sharing the same phylogenetic clade appear to have similar expression patterns.

  11. Survival of Phytophthora species and other pathogens in soilless media components or soil and their eradication with aerated steam

    Treesearch

    R.G. Linderman; E.A. Davis

    2006-01-01

    Phytophthora ramorum, while thought to be primarily an aerial pathogen, can be introduced into soilless potting media in the nursery industry as sporangia or chlamydospores and be disseminated widely without being detected. Inoculum of this pathogen, both North American (A2) and European (A1) isolates were used to infest potting media components or...

  12. Phytophthora Species, New Threats to the Plant Health in Korea

    PubMed Central

    Hyun, Ik-Hwa; Choi, Woobong

    2014-01-01

    Given the lack of a resistant genetic pool in host plants, the introduction of exotic invasive pathogens can result in epidemics that affect a specific ecosystem and economy. Plant quarantine, which is designed to protect endemic plant resources, is a highly invaluable safeguard that should keep biosecurity with increasing international trade and global transportation. A total of 34 species of plant pathogens including Phytophthora infestans were documented as introduced from other countries into Korea from 1900 to 2010. The genus Phytophthora, classified in oomycetes, includes more than 120 species that are mostly recognized worldwide as highly invasive plant pathogens. After 2000, over 50 new species of Phytophthora were identified internationally as plant pathogens occurring in crops and forest trees. In Korea, Phytophthora is also one of the most serious plant pathogens. To date, 22 species (about one-fifth of known species) of the genus have been identified and reported as plant pathogens in the country. The likelihood of new exotic Phytophthora species being introduced into Korea continues to increase, thus necessitating intensive plant quarantine inspections. As new potential threats to plant health in Korea, six Phytophthora species, namely, P. alni, P. inundata, P. kernoviae, P. pinifolia, P. quercina, and P. ramorum, are discussed in this review with focus on history, disease, biology, management, and plant quarantine issues. PMID:25506298

  13. Phytophthora tentaculata

    Treesearch

    Suzanne Rooney-Latham; Cheryl Blomquist; Ted Swiecki; Elizabeth Bernhardt

    2015-01-01

    Phytophthora tentaculata Kröber & Marwitz was described in 1993 in Germany on greenhouse-grown nursery ornamentals. It has since been found in Italy, Spain, China and the U.S. (California) causing a root and stem rot of many different plant species including nursery-grown native species used for habitat restoration. P. tentaculata...

  14. Forest Phytophthoras

    Treesearch

    J. L. Parke

    2013-01-01

    Profiles are provided for 5 forest Phytopthora species: P. kernoviae, P. pinifolia, P.alni, P. cinnamomi, P.katsurae. Also presented are a "Host and Habitat Index for Phytophthora Species in Oregon" and "Histopathological Investigations of the Infection Process and Propagule Development of...

  15. Landscape connectivity influences the establishment of Phytophthora ramorum

    Treesearch

    Emiko T. Condeso; Ross K. Meentemeyer

    2008-01-01

    As the emergence of invasive pathogens and their impacts on ecological communities increases, so has the interest in understanding how landscape pattern (in other words the configuration and composition of suitable habitat) affects their establishment and spread. Plant pathogen invasions are inherently spatial, but few studies have demonstrated the role of landscape...

  16. Survival of Phytophthora ramorum Chlamydospores at high and low temperatures

    Treesearch

    Paul W. Tooley; Marsha Browning

    2008-01-01

    Chlamydospores were produced as described by Colburn and Shishkoff (Phytopathology 96:S25). Samples (5cc) of chlamydospores in sand inoculum were placed in 15 ml conical plastic test tubes and incubated at selected temperatures for 1, 2, 3, 4, and 7 days. Following incubation, tube contents were resuspended in 0.2 percent water agar and 1 ml was plated onto PARPH...

  17. Laboratory diagnosis of Phytophthora ramorum from field samples

    Treesearch

    Cheryl Blomquist; Thomas L. Kubisiak

    2003-01-01

    A plant disease should never be diagnosed on the basis of a single test. Using as much information as possible leads to the most informed diagnosis. The species of host plant, its symptoms, the location of the plant, the status of the county or state (known infested versus not infested with the pathogen), the culture results, and the results of DNA tests...

  18. Phytophthora ramorum: How it got here and how it spread

    USDA-ARS?s Scientific Manuscript database

    The sudden oak death pathogen might have arrived on the U.S. West Coast circa 5-15 years before its first detection in the mid 1990s. Sudden oak death has caused disease of epidemic proportions on tanoak, Japanese larch and live oak. This article provides a brief chronology of the sudden oak death ...

  19. Host-induced phenotypic diversification in Phytophthora ramorum

    Treesearch

    Takao Kasuga; Mai Bui; Christine Shoemaker; Elizabeth Bernhardt; Tedmund Swiecki; Kamyar Aram; David Rizzo; Melina Kozanitas; Matteo Garbelotto

    2013-01-01

    Forestry, agriculture, and native ecosystems face ever-increasing threats by invasive species. Not all introduced species are, however, invasive. In order to establish and persist in a non-native land, introduced species have to adapt to different environments, unfamiliar food, and predators. There are a number of examples where invasive species evolved quickly in non-...

  20. Isolation and characterization of phytotoxins secreted by Phytophthora ramorum

    Treesearch

    Daniel K. Manter; Rick G. Kelsey; Joseph J. Karchesy

    2006-01-01

    Most Phythophthora species secrete a variety of small, hydrophilic proteins that induce a hypersensitive-like response to varying degrees in host and non-host plant species. Our research focuses on the potential role of these proteins in the biology and susceptibility of host species to sudden oak death (SOD). In this paper we reported on the...

  1. Contemporary California Indians, oaks and Sudden Oak Death (Phytophthora ramorum)

    Treesearch

    Beverly R. Ortiz

    2008-01-01

    This paper begins with a survey of contemporary California Indian utilization of acorns for food, including an examination of: (1) familial, community and cultural contexts in which acorn is shared and eaten; (2) new and old acorn processing techniques in use today and the foods that result; (3) the symbolic context of the foods in terms of ecological and social...

  2. Human activity and the spread of Phytophthora ramorum

    Treesearch

    Hall J. Cushman; Michelle Cooper; Ross K. Meentemeyer; Shelly Benson

    2008-01-01

    Increasing numbers of studies are finding that humans can facilitate the spread of exotic plant species in protected wildlands. Hiking trails commonly serve as conduits for invaders and the number of exotic plant species occurring in protected areas is often correlated positively with visitation rates. Despite such evidence linking human activity to the spread of...

  3. Phytophthora cinnamomi.

    PubMed

    Hardham, Adrienne R; Blackman, Leila M

    2017-05-18

    Phytophthora cinnamomi is one of the most devastating plant pathogens in the world. It infects close to 5000 species of plants, including many of importance in agriculture, forestry and horticulture. The inadvertent introduction of P. cinnamomi into natural ecosystems, including a number of recognized Global Biodiversity Hotspots, has had disastrous consequences for the environment and the biodiversity of flora and fauna. The genus Phytophthora belongs to the Class Oomycetes, a group of fungus-like organisms that initiate plant disease through the production of motile zoospores. Disease control is difficult in agricultural and forestry situations and even more challenging in natural ecosystems as a result of the scale of the problem and the limited range of effective chemical inhibitors. The development of sustainable control measures for the future management of P. cinnamomi requires a comprehensive understanding of the cellular and molecular basis of pathogen development and pathogenicity. The application of next-generation sequencing technologies to generate genomic and transcriptomic data promises to underpin a new era in P. cinnamomi research and discovery. The aim of this review is to integrate bioinformatic analyses of P. cinnamomi sequence data with current knowledge of the cellular and molecular basis of P. cinnamomi growth, development and plant infection. The goal is to provide a framework for future research by highlighting potential pathogenicity genes, shedding light on their possible functions and identifying suitable targets for future control measures. Phytophthora cinnamomi Rands; Kingdom Chromista; Phylum Oomycota or Pseudofungi; Class Oomycetes; Order Peronosporales; Family Peronosporaceae; genus Phytophthora. Infects about 5000 species of plants, including 4000 Australian native species. Host plants important for agriculture and forestry include avocado, chestnut, macadamia, oak, peach and pineapple. A root pathogen which causes rotting of fine

  4. Carbohydrate-related enzymes of important Phytophthora plant pathogens.

    PubMed

    Brouwer, Henk; Coutinho, Pedro M; Henrissat, Bernard; de Vries, Ronald P

    2014-11-01

    Carbohydrate-Active enZymes (CAZymes) form particularly interesting targets to study in plant pathogens. Despite the fact that many CAZymes are pathogenicity factors, oomycete CAZymes have received significantly less attention than effectors in the literature. Here we present an analysis of the CAZymes present in the Phytophthora infestans, Ph. ramorum, Ph. sojae and Pythium ultimum genomes compared to growth of these species on a range of different carbon sources. Growth on these carbon sources indicates that the size of enzyme families involved in degradation of cell-wall related substrates like cellulose, xylan and pectin is not always a good predictor of growth on these substrates. While a capacity to degrade xylan and cellulose exists the products are not fully saccharified and used as a carbon source. The Phytophthora genomes encode larger CAZyme sets when compared to Py. ultimum, and encode putative cutinases, GH12 xyloglucanases and GH10 xylanases that are missing in the Py. ultimum genome. Phytophthora spp. also encode a larger number of enzyme families and genes involved in pectin degradation. No loss or gain of complete enzyme families was found between the Phytophthora genomes, but there are some marked differences in the size of some enzyme families.

  5. Foliar susceptibility of eastern oak species to Phytophthora infection

    Treesearch

    Y. Balci; S. Balci; W.L. MacDonald; K.W. Gottschalk

    2008-01-01

    Seven different Phytophthora species were used to test the foliar susceptibility of the common eastern US oak species and understory plants to Phytophthora infection. The Phytophthora species employed were Phytophthora cambivora, Phytophthora cinnamomi, Phytophthora citricola, Phytophthora europaea,...

  6. Pyrosequencing of environmental soil samples reveals biodiversity of the Phytophthora resident community in chestnut forests.

    PubMed

    Vannini, Andrea; Bruni, Natalia; Tomassini, Alessia; Franceschini, Selma; Vettraino, Anna Maria

    2013-09-01

    Pyrosequencing analysis was performed on soils from Italian chestnut groves to evaluate the diversity of the resident Phytophthora community. Sequences analysed with a custom database discriminated 15 pathogenic Phytophthoras including species common to chestnut soils, while a total of nine species were detected with baiting. The two sites studied differed in Phytophthora diversity and the presence of specific taxa responded to specific ecological traits of the sites. Furthermore, some species not previously recorded were represented by a discrete number of reads; among these species, Phytophthora ramorum was detected at both sites. Pyrosequencing was demonstrated to be a very sensitive technique to describe the Phytophthora community in soil and was able to detect species not easy to be isolated from soil with standard baiting techniques. In particular, pyrosequencing is an highly efficient tool for investigating the colonization of new environments by alien species, and for ecological and adaptive studies coupled with biological detection methods. This study represents the first application of pyrosequencing for describing Phytophthoras in environmental soil samples.

  7. Phytophthora borealis and Phytophthora riparia , new species in Phytophthora ITS Clade 6

    Treesearch

    Everrett Hansen; Paul Reeser; Wendy Sutton

    2012-01-01

    Phytopthora borealis and Phytophthora riparia were identified in recent Phytophthora surveys in forest streams in Oregon, California and Alaska are described as new species in Phytophthora ITS Clade 6. They are similar in growth form and morphology to P. gonapodyides...

  8. Phytophthora kernoviae sp. nov., an invasive pathogen causing bleeding stem lesions on forest trees and foliar necrosis of ornamentals in the UK.

    PubMed

    Brasier, Clive M; Beales, Paul A; Kirk, Susan A; Denman, Sandra; Rose, Joan

    2005-08-01

    A new Phytophthora pathogen of trees and shrubs, previously informally designated Phytophthora taxon C, is formally named here as P. kernoviae. P. kernoviae was discovered in late 2003 during surveys of woodlands in Cornwall, south-west England, for the presence of another invasive pathogen, P. ramorum. P. kernoviae is self-fertile (homothallic), having plerotic oogonia, often with distinctly tapered stalks and amphigynous antheridia. It produces papillate sporangia, sometimes markedly asymmetric with medium length pedicels. Its optimum temperature for growth is ca 18 degrees C and upper limit ca 26 degrees. Currently, P. kernoviae is especially noted for causing bleeding stem lesions on mature Fagus sylvatica and foliar and stem necrosis of Rhododendron ponticum. P. kernoviae is the latest of several invasive tree Phytophthoras recently identified in the UK. Its geographical origins and the possible plant health risk it poses are discussed.

  9. The inclusion of downy mildews in a multi-locus-dataset and its reanalysis reveals a high degree of paraphyly in Phytophthora.

    PubMed

    Runge, Fabian; Telle, Sabine; Ploch, Sebastian; Savory, Elizabeth; Day, Brad; Sharma, Rahul; Thines, Marco

    2011-12-01

    Pathogens belonging to the Oomycota, a group of heterokont, fungal-like organisms, are amongst the most notorious pathogens in agriculture. In particular, the obligate biotrophic downy mildews and the hemibiotrophic members of the genus Phytophthora are responsible for a huge variety of destructive diseases, including sudden oak death caused by P. ramorum, potato late blight caused by P. infestans, cucurbit downy mildew caused by Pseudoperonospora cubensis, and grape downy mildew caused by Plasmopara viticola. About 800 species of downy mildews and roughly 100 species of Phytophthora are currently accepted, and recent studies have revealed that these groups are closely related. However, the degree to which Phytophthora is paraphyletic and where exactly the downy mildews insert into this genus in relation to other clades could not be inferred with certainty to date. Here we present a molecular phylogeny encompassing all clades of Phytophthora as represented in a multi-locus dataset and two representatives of the monophyletic downy mildews from divergent genera. Our results demonstrate that Phytophthora is at least six times paraphyletic with respect to the downy mildews. The downy mildew representatives are consistently nested within clade 4 (contains Phytophthora palmivora), which is placed sister to clade 1 (contains Phytophthora infestans). This finding would either necessitate placing all downy mildews and Phytopthora species in a single genus, either under the oldest generic name Peronospora or by conservation the later name Phytophthora, or the description of at least six new genera within Phytophthora. The complications of both options are discussed, and it is concluded that the latter is preferable, as it warrants fewer name changes and is more practical.

  10. Fighting phytophthora in blueberries

    USDA-ARS?s Scientific Manuscript database

    Phytophthora cinnamomi Rands is a ubiquitous soilborne pathogen associated with root rot in many woody perennial plant species, including highbush blueberry (Vaccinium sp.). To identify genotypes with resistance to the pathogen, cultivars and advanced selections of highbush blueberry were grown in a...

  11. Evolution of the cutinase gene family: evidence for lateral gene transfer of a candidate Phytophthora virulence factor.

    PubMed

    Belbahri, Lassaad; Calmin, Gautier; Mauch, Felix; Andersson, Jan O

    2008-01-31

    Lateral gene transfer (LGT) can facilitate the acquisition of new functions in recipient lineages, which may enable them to colonize new environments. Several recent publications have shown that gene transfer between prokaryotes and eukaryotes occurs with appreciable frequency. Here we present a study of interdomain gene transfer of cutinases -- well documented virulence factors in fungi -- between eukaryotic plant pathogens Phytophthora species and prokaryotic bacterial lineages. Two putative cutinase genes were cloned from Phytophthora brassicae and Northern blotting experiments showed that these genes are expressed early during the infection of the host Arabidopsis thaliana and induced during cyst germination of the pathogen. Analysis of the gene organisation of this gene family in Phytophthora ramorum and P. sojae showed three and ten copies in tight succession within a region of 5 and 25 kb, respectively, probably indicating a recent expansion in Phytophthora lineages by gene duplications. Bioinformatic analyses identified orthologues only in three genera of Actinobacteria, and in two distantly related eukaryotic groups: oomycetes and fungi. Together with phylogenetic analyses this limited distribution of the gene in the tree of life strongly support a scenario where cutinase genes originated after the origin of land plants in a microbial lineage living in proximity of plants and subsequently were transferred between distantly related plant-degrading microbes. More precisely, a cutinase gene was likely acquired by an ancestor of P. brassicae, P. sojae, P. infestans and P. ramorum, possibly from an actinobacterial source, suggesting that gene transfer might be an important mechanism in the evolution of their virulence. These findings could indeed provide an interesting model system to study acquisition of virulence factors in these important plant pathogens.

  12. Development of Rapid Isothermal Amplification Assays for Detection of Phytophthora spp. in Plant Tissue.

    PubMed

    Miles, Timothy D; Martin, Frank N; Coffey, Michael D

    2015-02-01

    Several isothermal amplification techniques recently have been developed that are tolerant of inhibitors present in many plant extracts, which can reduce the need for obtaining purified DNA for running diagnostic assays. One such commercially available technique that has similarities with real-time polymerase chain reaction (PCR) for designing primers and a labeled probe is recombinase polymerase amplification (RPA). This technology was used to develop two simple and rapid approaches for detection of Phytophthora spp.: one genus-specific assay multiplexed with a plant internal control and the other species-specific assays for Phytophthora ramorum and P. kernoviae. All assays were tested for sensitivity (ranging from 3 ng to 1 fg of DNA) and specificity using DNA extracted from more than 136 Phytophthora taxa, 21 Pythium spp., 1 Phytopythium sp., and a wide range of plant species. The lower limit of linear detection using purified DNA was 200 to 300 fg of DNA in all pathogen RPA assays. Six different extraction buffers were tested for use during plant tissue maceration and the assays were validated in the field by collecting 222 symptomatic plant samples from over 50 different hosts. Only 56 samples were culture positive for Phytophthora spp. whereas 91 were positive using the Phytophthora genus-specific RPA test and a TaqMan real-time PCR assay. A technique for the generation of sequencing templates from positive RPA amplifications to confirm species identification was also developed. These RPA assays have added benefits over traditional technologies because they are rapid (results can be obtained in as little as 15 min), do not require DNA extraction or extensive training to complete, use less expensive portable equipment than PCR-based assays, and are significantly more specific than current immunologically based methods. This should provide a rapid, field-deployable capability for pathogen detection that will facilitate point-of-sample collection processing

  13. A Phytophthora infestans Cystatin-Like Protein Targets a Novel Tomato Papain-Like Apoplastic Protease1[W][OA

    PubMed Central

    Tian, Miaoying; Win, Joe; Song, Jing; van der Hoorn, Renier; van der Knaap, Esther; Kamoun, Sophien

    2007-01-01

    There is emerging evidence that the proteolytic machinery of plants plays important roles in defense against pathogens. The oomycete pathogen Phytophthora infestans, the agent of the devastating late blight disease of tomato (Lycopersicon esculentum) and potato (Solanum tuberosum), has evolved an arsenal of protease inhibitors to overcome the action of host proteases. Previously, we described a family of 14 Kazal-like extracellular serine protease inhibitors from P. infestans. Among these, EPI1 and EPI10 bind and inhibit the pathogenesis-related (PR) P69B subtilisin-like serine protease of tomato. Here, we describe EPIC1 to EPIC4, a new family of P. infestans secreted proteins with similarity to cystatin-like protease inhibitor domains. Among these, the epiC1 and epiC2 genes lacked orthologs in Phytophthora sojae and Phytophthora ramorum, were relatively fast-evolving within P. infestans, and were up-regulated during infection of tomato, suggesting a role during P. infestans-host interactions. Biochemical functional analyses revealed that EPIC2B interacts with and inhibits a novel papain-like extracellular cysteine protease, termed Phytophthora Inhibited Protease 1 (PIP1). Characterization of PIP1 revealed that it is a PR protein closely related to Rcr3, a tomato apoplastic cysteine protease that functions in fungal resistance. Altogether, this and earlier studies suggest that interplay between host proteases of diverse catalytic families and pathogen inhibitors is a general defense-counterdefense process in plant-pathogen interactions. PMID:17085509

  14. Genome-wide sequencing of Phytophthora lateralis reveals genetic variation among isolates from Lawson cypress (Chamaecyparis lawsoniana) in Northern Ireland.

    PubMed

    Quinn, Lisa; O'Neill, Paul A; Harrison, James; Paskiewicz, Konrad H; McCracken, Alistair R; Cooke, Louise R; Grant, Murray R; Studholme, David J

    2013-07-01

    Phytophthora lateralis is a fungus-like (oomycete) pathogen of trees in the family Cupressaceae, including Chamaecyparis lawsoniana (Lawson cypress or Port Orford cedar). Known in North America since the 1920s, presumably having been accidentally introduced from its assumed East Asian centre of origin, until recently, this pathogen has not been identified causing disease in Europe except for a few isolated outbreaks. However, since 2010, there have been several reports of infection of C. lawsoniana by P. lateralis in the United Kingdom, including Northern Ireland. We sequenced the genomes of four isolates of P. lateralis from two sites in Northern Ireland in 2011. Comparison with the closely related tree and shrub pathogen P. ramorum (cause of ramorum disease of larch and other species in the UK) shows that P. lateralis shares 91.47% nucleotide sequence identity over the core conserved compartments of the genome. The genomes of the four Northern Ireland isolates are almost identical, but we identified several single-nucleotide polymorphisms (SNPs) that distinguish between isolates, thereby presenting potential molecular markers of use for tracking routes of spread and in epidemiological studies. Our data reveal very low rates of heterozygosity (compared with P. ramorum), consistent with inbreeding within this P. lateralis population.

  15. Structural and functional profile of the carbohydrate esterase gene complement in Phytophthora infestans.

    PubMed

    Ospina-Giraldo, Manuel D; McWalters, Jessica; Seyer, Lauren

    2010-12-01

    The plant cell cuticle is the first obstacle for penetration of the host by plant pathogens. To breach this barrier, most pathogenic fungi employ a complex assortment of cell wall-degrading enzymes including carbohydrate esterases, glycoside hydrolases, and polysaccharide lyases. We characterized the full complement of carbohydrate esterase-coding genes in three Phytophthora species and analyzed the expression of cutinase in vitro and in planta; we also determined the cutinase allele distribution in multiple isolates of P. infestans. Our investigations revealed that there are 49, 21, and 37 esterase homologs in the P. infestans, P. ramorum, and P. sojae genomes, respectively, with a considerable number predicted to be extracellular. Four cutinase gene copies were found in both the P. infestans and P. ramorum genomes, while 16 copies were found in P. sojae. Transcriptional analyses of cutinase in P. infestans revealed that its expression level during infection is significantly upregulated at all time points compared to that of the same gene in mycelium grown in vitro. Expression achieves maximum values at 15 hpi, declining at subsequent time points. These results may suggest, therefore, that cutinase most likely plays a role in P. infestans pathogenicity.

  16. Influence of oak woodland composition and structure on infection by Phytophthora ramorum

    Treesearch

    Nathan Rank; Hall Cushman; Brian Anacker; David Rizzo; Ross Meentemeyer

    2008-01-01

    Introduced plant pathogens have major ecological impacts in many parts of the world. While the spread of pathogens can be strongly mediated by the composition and structure of local host plant communities, little is known about effects of plant community structure on invasion dynamics of introduced pathogens. The progress of infection by the invasive pathogen ...

  17. Preliminary observations of heat treatment to control Phytophthora ramorum in infected wood species: an extended abstract

    Treesearch

    K.M. Tubajika; R. Singh; Shelly J.R.

    2008-01-01

    Identification of appropriate phytosanitary treatments that can be used for certifying solid wood packing material movement from areas infested or threatened by actionable plant pests and pathogens into uninfested areas is mportant. Heat treatment has been used on commodities to control fungal diseases and insect infestations for many years. The restricted use of...

  18. Genotypic diversity of european Phytophthora ramorum isolates based on SSR analysis

    Treesearch

    Kris Van Poucke; Annelies Vercauteren; Martine Maes; Sabine Werres; Kurt Heungens

    2013-01-01

    in Scotland were genotyped using seven microsatellite markers as described by Vercauteren et al. (2010). Thirty multilocus genotypes were identified within the Scottish population, with 51 percent of the isolates belonging to the main European genotype EU1MG1 and 13 unique detected genotypes. Ten of those genotypes were site specific, often represented by...

  19. Genetic diversity of Phytophthora ramorum in nursery trade and managed environment in Scotland

    Treesearch

    Alexandra Schlenzig; David Cook

    2013-01-01

    in Scotland were genotyped using seven microsatellite markers as described by Vercauteren et al. (2010). Thirty multilocus genotypes were identified within the Scottish population, with 51 percent of the isolates belonging to the main European genotype EU1MG1 and 13 unique detected genotypes. Ten of those genotypes were site specific, often represented by...

  20. Implication of global climate change on the distribution and activity of Phytophthora ramorum

    Treesearch

    Robert C. Venette

    2009-01-01

    Global climate change is predicted to alter the distribution and activity of several forest pathogens. Boland et al. (2004) suggested that climate change might affect pathogen establishment, rate of disease progress, and the duration of...

  1. Host-induced aneuploidy and phenotypic diversification in the Sudden Oak Death pathogen Phytophthora ramorum

    USDA-ARS?s Scientific Manuscript database

    Aneuploidy can result in significant phenotypic changes, which can sometimes be selectively advantageous. For example, aneuploidy confers resistance to antifungal drugs in human pathogenic fungi. Aneuploidy has also been observed in invasive fungal and oomycete plant pathogens in the field. Environm...

  2. Influence of woodland expansion (1942 to 2000) on the establishment of Phytophthora ramorum

    Treesearch

    Ross K. Meentemeyer; Nathan E. Rank; Brian L. Anacker; David M. Rizzo; Hall J. Cushman

    2008-01-01

    Human land-use practices have resulted in dramatic alterations of forest ecosystems worldwide. By modifying transmission pathways and habitat structure, land use changes are being increasingly implicated in the emergence of infectious plant disease. In this research, we examined the effects of human-related land-cover change on the establishment of the invasive plant...

  3. Diagnosis and Management of Phytophthora ramorum canker in canyon live oak, an atypical bole canker host

    Treesearch

    Tedmund J. Swiecki; Elizabeth Bernhardt; Kamyar Aram; David Rizzo

    2013-01-01

    Diagnosis of sudden oak death (SOD) in tanoak (Notholithocarpus densiflorus (Hook. & Arn.) Manos, Cannon & S.H. Oh) and susceptible red/black oak species (coast live oak, Quercus agrifolia Née; Shreve oak, Q. parvula Greene var. shrevei (C.H. Mull.) Nixon; California...

  4. Comparing Phytophthora ramorum diagnostic protocols for the national Sudden Oak death stream monitoring program

    Treesearch

    W. Sutton; E.M. Hansen; P. Reeser; A. Kanaskie

    2008-01-01

    Oregon was a participant in the pilot test of the national stream monitoring protocol for SOD. We routinely and continuously monitor about 50 streams in and near the SOD quarantine area in southwest Oregon using foliage baits. For the national protocol, we added six additional streams beyond the area of known infestation, and compared results from different diagnostic...

  5. 78 FR 58993 - Notice of Request for Extension of Approval of an Information Collection; Phytophthora Ramorum...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-25

    ... with the regulations for the interstate movement of regulated articles to prevent the spread of... coming. FOR FURTHER INFORMATION CONTACT: For information on the regulations for the interstate movement... Agriculture to restrict the importation, entry, or interstate movement of plants, plant products, and other...

  6. Survey and analysis of microsatellites from transcript sequences in Phytophthora species: frequency, distribution, and potential as markers for the genus

    PubMed Central

    Garnica, Diana P; Pinzón, Andrés M; Quesada-Ocampo, Lina M; Bernal, Adriana J; Barreto, Emiliano; Grünwald, Niklaus J; Restrepo, Silvia

    2006-01-01

    Background Members of the genus Phytophthora are notorious pathogens with world-wide distribution. The most devastating species include P. infestans, P. ramorum and P. sojae. In order to develop molecular methods for routinely characterizing their populations and to gain a better insight into the organization and evolution of their genomes, we used an in silico approach to survey and compare simple sequence repeats (SSRs) in transcript sequences from these three species. We compared the occurrence, relative abundance, relative density and cross-species transferability of the SSRs in these oomycetes. Results The number of SSRs in oomycetes transcribed sequences is low and long SSRs are rare. The in silico transferability of SSRs among the Phytophthora species was analyzed for all sets generated, and primers were selected on the basis of similarity as possible candidates for transferability to other Phytophthora species. Sequences encoding putative pathogenicity factors from all three Phytophthora species were also surveyed for presence of SSRs. However, no correlation between gene function and SSR abundance was observed. The SSR survey results, and the primer pairs designed for all SSRs from the three species, were deposited in a public database. Conclusion In all cases the most common SSRs were trinucleotide repeat units with low repeat numbers. A proportion (7.5%) of primers could be transferred with 90% similarity between at least two species of Phytophthora. This information represents a valuable source of molecular markers for use in population genetics, genetic mapping and strain fingerprinting studies of oomycetes, and illustrates how genomic databases can be exploited to generate data-mining filters for SSRs before experimental validation. PMID:17007642

  7. Phytophthora sojae: Diversity among and within Populations

    USDA-ARS?s Scientific Manuscript database

    Soybean production is increasing around the world and, to no surprise, so are the reports of soybean diseases caused by Phytophthora sojae, including Phytophthora seed, root, and stem rot. Phytophthora sojae is a diploid oomycete, which is homothallic and is limited to primarily one host: the soybe...

  8. Bioinformatic Inference of Specific and General Transcription Factor Binding Sites in the Plant Pathogen Phytophthora infestans

    PubMed Central

    Seidl, Michael F; Wang, Rui-Peng; Van den Ackerveken, Guido; Govers, Francine; Snel, Berend

    2012-01-01

    Plant infection by oomycete pathogens is a complex process. It requires precise expression of a plethora of genes in the pathogen that contribute to a successful interaction with the host. Whereas much effort has been made to uncover the molecular systems underlying this infection process, mechanisms of transcriptional regulation of the genes involved remain largely unknown. We performed the first systematic de-novo DNA motif discovery analysis in Phytophthora. To this end, we utilized the genome sequence of the late blight pathogen Phytophthora infestans and two related Phytophthora species (P. ramorum and P. sojae), as well as genome-wide in planta gene expression data to systematically predict 19 conserved DNA motifs. This catalog describes common eukaryotic promoter elements whose functionality is supported by the presence of orthologs of known general transcription factors. Together with strong functional enrichment of the common promoter elements towards effector genes involved in pathogenicity, we obtained a new and expanded picture of the promoter structure in P. infestans. More intriguingly, we identified specific DNA motifs that are either highly abundant or whose presence is significantly correlated with gene expression levels during infection. Several of these motifs are observed upstream of genes encoding transporters, RXLR effectors, but also transcriptional regulators. Motifs that are observed upstream of known pathogenicity-related genes are potentially important binding sites for transcription factors. Our analyses add substantial knowledge to the as of yet virtually unexplored question regarding general and specific gene regulation in this important class of pathogens. We propose hypotheses on the effects of cis-regulatory motifs on the gene regulation of pathogenicity-related genes and pinpoint motifs that are prime targets for further experimental validation. PMID:23251489

  9. Managing Phytophthora Disease with Fungicides

    USDA-ARS?s Scientific Manuscript database

    Phytophthora capsici ranks as a top threat to production of Cucurbitaceae, Solanaceae and most recently Fabaceae vegetables. Available and effective fungicides for disease management are limited and populations of P. capsici in many growing areas have become insensitive to mefenoxam. Efficacy of f...

  10. NEP1 orthologs encoding necrosis and ethylene inducing proteins exist as a multigene family in Phytophthora megakarya, causal agent of black pod disease on cacao.

    PubMed

    Bae, Hanhong; Bowers, John H; Tooley, Paul W; Bailey, Bryan A

    2005-12-01

    Phvytophthora megakarya is a devastating oomycete pathogen that causes black pod disease in cacao. Phytophthora species produce a protein that has a similar sequence to the necrosis and ethylene inducing protein (Nep1) of Fusarium oxysporum. Multiple copies of NEP1 orthologs (PmegNEP) have been identified in P. megakarya and four other Phytophthora species (P. citrophthora, P. capsici, P. palmivora, and P. sojae). Genome database searches confirmed the existence of multiple copies of NEP1 orthologs in P. sojae and P. ramorum. In this study, nine different PmegNEP orthologs from P. megakarya strain Mk-1 were identified and analyzed. Of these nine orthologs, six were expressed in mycelium and in P. megakarya zoospore-infected cacao leaf tissue. The remaining two clones are either regulated differently, or are nonfunctional genes. Sequence analysis revealed that six PmegNEP orthologs were organized in two clusters of three orthologs each in the P. megakarya genome. Evidence is presented for the instability in the P. megakarya genome resulting from duplications, inversions, and fused genes resulting in multiple NEP1 orthologs. Traits characteristic of the Phytophthora genome, such as the clustering of NEP1 orthologs, the lack of CATT and TATA boxes, the lack of introns, and the short distance between ORFs were also observed.

  11. Activation of Zoosporogenesis-Specific Genes in Phytophthora infestans Involves a 7-Nucleotide Promoter Motif and Cold-Induced Membrane Rigidity

    PubMed Central

    Tani, Shuji; Judelson, Howard

    2006-01-01

    Infections of plants by the oomycete Phytophthora infestans typically result from zoospores, which develop from sporangia at cold temperatures. To help understand the relevant cold-induced signaling pathway, factors regulating the transcription of the zoosporogenesis-specific NIF (nuclear LIM-interactor-interacting factor) gene family were examined. Sequences required for inducing PinifC3 were identified by analyzing truncated and mutated promoters using the β-glucuronidase reporter in stable transformants. A 7-nucleotide (nt) sequence located 139 bases upstream of the major transcription start point (GGACGAG) proved essential for the induction of PinifC3 when sporangia were shifted from ambient to cold temperatures. The motif, named the cold box, also conferred cold inducibility to a promoter normally activated only during sexual development. An identical motif was detected in the two other zoosporogenesis-specific NIF genes from P. infestans and three Phytophthora sojae orthologues, and a closely related sequence was found in Phytophthora ramorum orthologues. The 7-nt motif was also found in the promoters of other zoosporogenesis-induced genes. The presence of a cold box-interacting protein in nuclear extracts of P. infestans sporangia was demonstrated using electrophoretic mobility shift assays. Furthermore, zoospore release and cold box-regulated transcription were stimulated by the membrane rigidizer dimethyl sulfoxide and inhibited by the membrane fluidizer benzyl alcohol. The data therefore delineate a pathway in which sporangia perceive cold temperatures through membrane rigidity, which activates signals that drive both zoosporogenesis and cold-box-mediated transcription. PMID:16607021

  12. The Phytophthora species known as "Pg chlamydo"

    Treesearch

    Everett Hansen; Paul Reeser; Wendy Sutton

    2009-01-01

    Phytophthora taxon Pg chlamydo is perhaps the second most abundant Phytophthora species in the world, after P. gonapodyides, although it is commonly misidentified. Pg chlamydo is frequently encountered in streams and rivers in western North America, Argentina, China, and Europe. It has occasionally been...

  13. Screening Phytophthora rubi for fungicide resistance

    USDA-ARS?s Scientific Manuscript database

    Preliminary results from the survey for fungicide resistance in Phytophthora were reported at the 2016 Washington Small Fruit Conference. Phytophthora was isolated from diseased plants in 28 red raspberry fields and tested against mefenoxam, the active ingredient of Ridomil. Most isolates were ident...

  14. Pathogenic diversity of Phytophthora sojae and breeding strategies to develop Phytophthora-resistant soybeans

    USDA-ARS?s Scientific Manuscript database

    Phytophthora stem and root rot disease, caused by Phytophthora sojae, is one of the most destructive diseases of soybean (Glycine max (L.) Merr.), and has been increasing in several soybean-producing areas around the world. This disease induces serious limitations on soybean production, with yield l...

  15. The necrosis-inducing Phytophthora protein gene family of Phytophthora capsici is involved in pathogenicity

    USDA-ARS?s Scientific Manuscript database

    Phytophthora capsici is one of the most important pathogens limiting vegetable production worldwide. Necrosis-inducing Phytophthora protein (NPP), ocurring in phylogenetically distant organisms, is phytotoxic for dicotyledonous plants, but the mechanism of action has not been established. A gene fam...

  16. Introducing the Phytophthora database: an integrated resource for detecting, monitoring, and managing Phytophthora diseases

    Treesearch

    Kelly L. Ivors; Frank Martin; Michael Coffey; Izabela Makalowska; David M. Geiser; Seogchan Kang

    2008-01-01

    Its virulence and ability to spread rapidly throughout the world by various means establishes Phytophthora as one of the most important groups of plant pathogens. Discoveries of interspecific hybridization among Phytophthora species in nature, which could yield novel pathogens, further underscore the threat posed by members of this genus. The ability...

  17. Transcriptome analysis of tanoak reveals divergent mechanisms of innate and phosphite-induced resistance to Phytophthora ramorum

    Treesearch

    Catherine A. Eyre; Katherine J. Hayden; Peter Croucher; Shannon Schechter; Jessica W. Wright; Matteo Garbelotto

    2017-01-01

    Phosphite compounds have been used in the control of sudden oak death; however, their precise mode of action is not fully understood. To study the action of phosphite compounds in the context of naturally occurring host resistance, we first identified open-pollinated family groups that carried resistance, that is in which approximately 20% of offspring demonstrated a...

  18. Use of remotely sensed imagery to map Sudden Oak Death (Phytophthora ramorum) in the Santa Cruz Mountains

    NASA Astrophysics Data System (ADS)

    Gillis, Trinka

    This project sought a method to map Sudden Oak Death distribution in the Santa Cruz Mountains of California, a coastal mountain range and one of the locations where this disease was first observed. The project researched a method to identify forest affected by SOD using 30 m multi-spectral Landsat satellite imagery to classify tree mortality at the canopy-level throughout the study area, and applied that method to a time series of data to show pattern of spread. A successful methodology would be of interest to scientists trying to identify areas which escaped disease contagion, environmentalists attempting to quantify damage, and land managers evaluating the health of their forests. The more we can learn about the disease, the more chance we have to prevent further spread and damage to existing wild lands. The primary data source for this research was springtime Landsat Climate Data Record surface reflectance data. Non-forest areas were masked out using data produced by the National Land Cover Database and supplemental land cover classification from the Landsat 2011 Climate Data Record image. Areas with other known causes of tree death, as identified by Fire and Resource Assessment Program fire perimeter polygons, and US Department of Agriculture Forest Health Monitoring Program Aerial Detection Survey polygons, were also masked out. Within the remaining forested study area, manually-created points were classified based on the land cover contained by the corresponding Landsat 2011 pixel. These were used to extract value ranges from the Landsat bands and calculated vegetation indices. The range and index which best differentiated healthy from dead trees, SWIR/NIR, was applied to each Landsat scene in the time series to map tree mortality. Results Validation Points, classified using Google Earth high-resolution aerial imagery, were created to evaluate the accuracy of the mapping methodology for the 2011 data.

  19. In vitro foliage susceptibility of canary islands laurel forests: a model for better understanding the ecology of Phytophthora ramorum

    Treesearch

    Eduardo Moralejo; Enrique Descals

    2008-01-01

    The tree species that dominate the cloud-zone forests of Macaronesia, the coastal redwoods of California, the Valdivian forests of Chile, the Atlantic forests of Brazil and the podocarp forests of New Zealand are all examples of paleoendemic species that once had a much wider distribution. They appear to owe their survival to the particular environmental conditions...

  20. Detection of mRNA by reverse transcription PCR as an indicator of viability in Phytophthora ramorum

    Treesearch

    Antonio Chimento; Santa Olga Cacciola; Matteo Garbelotto

    2008-01-01

    Real-Time PCR technologies offer increasing opportunities to detect and study phytopathogenic fungi. They combine the sensitivity of conventional PCR with the generation of a specific fluorescent signal providing both real-time analysis of the reaction kinetics and quantification of specific DNA targets. Before the development of Real-Time PCR and...

  1. Symptoms associated with inoculation of stems on living Douglas-fir and Grand Fir Trees with Phytophthora ramorum

    Treesearch

    Gary Chastagner; Kathy Riley; Katie Coats; Marianne Elliott; Annie DeBauw; Norm Dart

    2010-01-01

    To obtain a better understanding of the potential risk of infection and colonization of living Douglas-fir (Pseudotsuga menziesii) and grand fir (Abies grandis) stems, the stems on over 150 trees of each species were inoculated at a Christmas tree farm near Los Gatos, California. This study had the following objectives: 1)...

  2. Detection of mRNA by reverse-transcription PCR as an indicator of viability in Phytophthora ramorum

    Treesearch

    A. Chimento; S.O. Cacciola; M. Garbelotto

    2011-01-01

    In the last few decades, the use of molecular tools has greatly improved the efficiency of plant disease diagnosis. However, one of the major setbacks of most molecular diagnostic approaches is their inability to differentiate between dead and viable pathogens. We propose a new strategy for the detection of plant pathogens, based on the use of mRNA as a viability...

  3. Phytophthora obscura sp. nov., a new species of the novel Phytophthora subclade 8d

    Treesearch

    N. J. Grünwald; S. Werres; E. M. Goss; C. R. Taylor; V. J. Fieland

    2012-01-01

    A new Phytophthora species was detected (i) in the USA, infecting foliage of Kalmia latifolia, (ii) in substrate underneath Pieris, and (iii) in Germany in soil samples underneath Aesculus hippocastanum showing disease symptoms. The new...

  4. Pathogenic diversity of Phytophthora sojae and breeding strategies to develop Phytophthora-resistant soybeans

    PubMed Central

    Sugimoto, Takuma; Kato, Masayasu; Yoshida, Shinya; Matsumoto, Isao; Kobayashi, Tamotsu; Kaga, Akito; Hajika, Makita; Yamamoto, Ryo; Watanabe, Kazuhiko; Aino, Masataka; Matoh, Toru; Walker, David R.; Biggs, Alan R.; Ishimoto, Masao

    2012-01-01

    Phytophthora stem and root rot, caused by Phytophthora sojae, is one of the most destructive diseases of soybean [Glycine max (L.) Merr.], and the incidence of this disease has been increasing in several soybean-producing areas around the world. This presents serious limitations for soybean production, with yield losses from 4 to 100%. The most effective method to reduce damage would be to grow Phytophthora-resistant soybean cultivars, and two types of host resistance have been described. Race-specific resistance conditioned by single dominant Rps (“resistance to Phytophthora sojae”) genes and quantitatively inherited partial resistance conferred by multiple genes could both provide protection from the pathogen. Molecular markers linked to Rps genes or quantitative trait loci (QTLs) underlying partial resistance have been identified on several molecular linkage groups corresponding to chromosomes. These markers can be used to screen for Phytophthora-resistant plants rapidly and efficiently, and to combine multiple resistance genes in the same background. This paper reviews what is currently known about pathogenic races of P. sojae in the USA and Japan, selection of sources of Rps genes or minor genes providing partial resistance, and the current state and future scope of breeding Phytophthora-resistant soybean cultivars. PMID:23136490

  5. Phytophthora lateralis on Port-Orford-cedar.

    Treesearch

    John. Hunt

    1959-01-01

    Results from annual surveys of the destructive Phytophthora root disease of Port-Orford-cedar (Chamaecyparis lawsoniana (A. Murr.) Parl.) show that the disease is gradually spreading and intensifying within the natural range of Port-Orford-cedar. The disease became established on native trees in the early 1950's in the vicinity of Coos Bay,...

  6. Hot spots of Phytophthora in commercial nurseries

    Treesearch

    Corina Junker; Patrick Goff; Stefan Wagner; Sabine Werres

    2017-01-01

    Studies have shown that nurseries are an important source for the spread of Phytophthora. Most surveys and studies focusing on the epidemiology of these pathogens in nurseries are based on sampling of symptomatic plants or on samples like water of different sources used for irrigation. There is little knowledge, however, on the survival and...

  7. Restoration of Mount Tamalpais forests destroyed by the sudden oak death pathogen

    Treesearch

    Richard C. Cobb; David M. Rizzo; Kerri Frangioso; Peter Hartsough; Janet Klein; Mike Swezy; Andrea Williams; Carl Sanders; Susan J. Frankel

    2017-01-01

    On Mt. Tamalpais, after nearly 20 years of accumulated disease impacts, some tanoak- (Notholithocarpus densiflorus) dominated forests where Phytophthora ramorum first emerged have converted to brushy fields of tanoak resprouts. Phytophthora ramorum has invaded throughout the...

  8. Host and habitat index for Phytophthora species in Oregon

    Treesearch

    Everett Hansen; Paul Reeser; Wendy Sutton; Laura. Sims

    2012-01-01

    In this contribution we compile existing records from available sources of reliably identified Phytophthora species from forests and forest trees in Oregon, USA. A searchable version of this information may be found in the Forest Phytophthoras of the World Disease Finder (select USA-Oregon). We have included isolations from soil and streams in...

  9. Phytophthora Database 2.0: update and future direction

    USDA-ARS?s Scientific Manuscript database

    The online community resource Phytophthora Database (PD) was developed to support accurate and rapid identification of Phytophthora and to help characterize and catalog the diversity and evolutionary relationships within the genus. Since its release in 2008, its sequence database has grown to cover ...

  10. Mapping resistance to Phytophthora cinnamomi in chestnut (Castanea sp.)

    Treesearch

    Bode A. Olukolu; C. Dana Nelson; Albert G. Abbott

    2012-01-01

    Phytophthora cinnamomi (Phytophthora crown and root rot, or ink disease) is now known to infect several hundred plant species in the world and is especially linked to the widespread death of mature chestnut (Castanea) and evergreen oak (Quercus ilex L.) trees in southeast United States. With an expanding...

  11. Host and habitat index for Phytophthora species in Oregon

    Treesearch

    Everett Hansen; Paul Reeser; Wendy Sutton; Laura Sims

    2013-01-01

    Phytophthora species are known as pathogens of agricultural crops or invasive pathogens destroying forests, and their prominent inclusion in various host-pathogen indices reflects this importance. It is increasingly evident, however, that Phytophthora species are abundant in streams in healthy forests and widespread in forest...

  12. Phytophthora root rot resistance in soybean E00003

    USDA-ARS?s Scientific Manuscript database

    Phytophthora root rot (PRR), caused by the oomycete Phytophthora sojae, is a devastating disease in soybean production. Using resistant cultivars has been suggested as the best solution for disease management. Michigan elite soybean E00003 is resistant to P. sojae and has been used as a PRR resist...

  13. Forest Phytophthora diseases in the Americas: 2007 - 2010

    Treesearch

    S. J. Frankel; E. M. Hansen

    2011-01-01

    Recent findings, policy, regulation, and management relating to tree disease caused by Phytophthora species in wildlands and nurseries of North and South America are reviewed. These include the isolation of Phytophthora alni uniformis Brasier & S.A.Kirk in Alaska, and detection of population shifts in NA1, NA2 and EU1...

  14. Development of Phytophthora fruit rot caused by Phytophthora capsici on resistant and susceptible watermelon fruit of different ages

    USDA-ARS?s Scientific Manuscript database

    Watermelon is an important crop grown in 44 states in the United States. Phytophthora fruit rot caused by Phytophthora capsici is a serious disease in the southeastern U.S., where over 50% of the watermelons are produced. The disease has resulted in severe losses to watermelon growers, especially in...

  15. Phytophthora-ID.org: A sequence-based Phytophthora identification tool

    Treesearch

    N.J. Grünwald; F.N. Martin; M.M. Larsen; C.M. Sullivan; C.M. Press; M.D. Coffey; E.M. Hansen; J.L. Parke

    2010-01-01

    Contemporary species identification relies strongly on sequence-based identification, yet resources for identification of many fungal and oomycete pathogens are rare. We developed two web-based, searchable databases for rapid identification of Phytophthora spp. based on sequencing of the internal transcribed spacer (ITS) or the cytochrome oxidase...

  16. Variation in capsidiol sensitivity between Phytophthora infestans and Phytophthora capsici is consistent with their host range.

    PubMed

    Giannakopoulou, Artemis; Schornack, Sebastian; Bozkurt, Tolga O; Haart, Dave; Ro, Dae-Kyun; Faraldos, Juan A; Kamoun, Sophien; O'Maille, Paul E

    2014-01-01

    Plants protect themselves against a variety of invading pathogenic organisms via sophisticated defence mechanisms. These responses include deployment of specialized antimicrobial compounds, such as phytoalexins, that rapidly accumulate at pathogen infection sites. However, the extent to which these compounds contribute to species-level resistance and their spectrum of action remain poorly understood. Capsidiol, a defense related phytoalexin, is produced by several solanaceous plants including pepper and tobacco during microbial attack. Interestingly, capsidiol differentially affects growth and germination of the oomycete pathogens Phytophthora infestans and Phytophthora capsici, although the underlying molecular mechanisms remain unknown. In this study we revisited the differential effect of capsidiol on P. infestans and P. capsici, using highly pure capsidiol preparations obtained from yeast engineered to express the capsidiol biosynthetic pathway. Taking advantage of transgenic Phytophthora strains expressing fluorescent markers, we developed a fluorescence-based method to determine the differential effect of capsidiol on Phytophtora growth. Using these assays, we confirm major differences in capsidiol sensitivity between P. infestans and P. capsici and demonstrate that capsidiol alters the growth behaviour of both Phytophthora species. Finally, we report intraspecific variation within P. infestans isolates towards capsidiol tolerance pointing to an arms race between the plant and the pathogens in deployment of defence related phytoalexins.

  17. Variation in Capsidiol Sensitivity between Phytophthora infestans and Phytophthora capsici Is Consistent with Their Host Range

    PubMed Central

    Giannakopoulou, Artemis; Schornack, Sebastian; Bozkurt, Tolga O.; Haart, Dave; Ro, Dae-Kyun; Faraldos, Juan A.; Kamoun, Sophien; O’Maille, Paul E.

    2014-01-01

    Plants protect themselves against a variety of invading pathogenic organisms via sophisticated defence mechanisms. These responses include deployment of specialized antimicrobial compounds, such as phytoalexins, that rapidly accumulate at pathogen infection sites. However, the extent to which these compounds contribute to species-level resistance and their spectrum of action remain poorly understood. Capsidiol, a defense related phytoalexin, is produced by several solanaceous plants including pepper and tobacco during microbial attack. Interestingly, capsidiol differentially affects growth and germination of the oomycete pathogens Phytophthora infestans and Phytophthora capsici, although the underlying molecular mechanisms remain unknown. In this study we revisited the differential effect of capsidiol on P. infestans and P. capsici, using highly pure capsidiol preparations obtained from yeast engineered to express the capsidiol biosynthetic pathway. Taking advantage of transgenic Phytophthora strains expressing fluorescent markers, we developed a fluorescence-based method to determine the differential effect of capsidiol on Phytophtora growth. Using these assays, we confirm major differences in capsidiol sensitivity between P. infestans and P. capsici and demonstrate that capsidiol alters the growth behaviour of both Phytophthora species. Finally, we report intraspecific variation within P. infestans isolates towards capsidiol tolerance pointing to an arms race between the plant and the pathogens in deployment of defence related phytoalexins. PMID:25203155

  18. Genome sequences of six Phytophthora species associated with forests in New Zealand

    PubMed Central

    Studholme, D.J.; McDougal, R.L.; Sambles, C.; Hansen, E.; Hardy, G.; Grant, M.; Ganley, R.J.; Williams, N.M.

    2015-01-01

    In New Zealand there has been a long association of Phytophthora diseases in forests, nurseries, remnant plantings and horticultural crops. However, new Phytophthora diseases of trees have recently emerged. Genome sequencing has been performed for 12 Phytophthora isolates, from six species: Phytophthora pluvialis, Phytophthora kernoviae, Phytophthora cinnamomi, Phytophthora agathidicida, Phytophthora multivora and Phytophthora taxon Totara. These sequences will enable comparative analyses to identify potential virulence strategies and ultimately facilitate better control strategies. This Whole Genome Shotgun data have been deposited in DDBJ/ENA/GenBank under the accession numbers LGTT00000000, LGTU00000000, JPWV00000000, JPWU00000000, LGSK00000000, LGSJ00000000, LGTR00000000, LGTS00000000, LGSM00000000, LGSL00000000, LGSO00000000, and LGSN00000000. PMID:26981359

  19. Genome sequences of six Phytophthora species associated with forests in New Zealand.

    PubMed

    Studholme, D J; McDougal, R L; Sambles, C; Hansen, E; Hardy, G; Grant, M; Ganley, R J; Williams, N M

    2016-03-01

    In New Zealand there has been a long association of Phytophthora diseases in forests, nurseries, remnant plantings and horticultural crops. However, new Phytophthora diseases of trees have recently emerged. Genome sequencing has been performed for 12 Phytophthora isolates, from six species: Phytophthora pluvialis, Phytophthora kernoviae, Phytophthora cinnamomi, Phytophthora agathidicida, Phytophthora multivora and Phytophthora taxon Totara. These sequences will enable comparative analyses to identify potential virulence strategies and ultimately facilitate better control strategies. This Whole Genome Shotgun data have been deposited in DDBJ/ENA/GenBank under the accession numbers LGTT00000000, LGTU00000000, JPWV00000000, JPWU00000000, LGSK00000000, LGSJ00000000, LGTR00000000, LGTS00000000, LGSM00000000, LGSL00000000, LGSO00000000, and LGSN00000000.

  20. Microbial acrobats: tracking the whereabouts of forest Phytophthora species

    Treesearch

    Susan J. Frankel

    2011-01-01

    Over the past few years, significant new findings have jolted the forest Phytophthora research community; the following is a synopsis of significant developments in our understanding of these adroit and often surprising organisms.

  1. Genetic transformation of the plant pathogens Phytophthora capsici and Phytophthora parasitica.

    PubMed Central

    Bailey, A M; Mena, G L; Herrera-Estrella, L

    1991-01-01

    Phytophthora capsici and P.parasitica were transformed to hygromycin B resistance using plasmids pCM54 and pHL1, which contain the bacterial hygromycin B phosphotransferase gene (hph) fused to promoter elements of the Ustilago maydis heat shock hsp70 gene. Enzymes Driselase and Novozyme 234 were used to generate protoplasts which were then transformed following exposure to plasmid DNA and polyethylene glycol 6000. Transformation frequencies of over 500 transformants per micrograms of DNA per 1 x 10(6) protoplasts were obtained. Plasmid pCM54 appears to be transmitted in Phytophthora spp. as an extra-chromosomal element through replication, as shown by Southern blot hybridization and by the loss of plasmid methylation. In addition, transformed strains retained their capacity of infecting Serrano pepper seedlings and Mc. Intosh apple fruits, the host plants for P.capsici and P.parasitica, respectively. Images PMID:1651483

  2. Genetic transformation of the plant pathogens Phytophthora capsici and Phytophthora parasitica.

    PubMed

    Bailey, A M; Mena, G L; Herrera-Estrella, L

    1991-08-11

    Phytophthora capsici and P.parasitica were transformed to hygromycin B resistance using plasmids pCM54 and pHL1, which contain the bacterial hygromycin B phosphotransferase gene (hph) fused to promoter elements of the Ustilago maydis heat shock hsp70 gene. Enzymes Driselase and Novozyme 234 were used to generate protoplasts which were then transformed following exposure to plasmid DNA and polyethylene glycol 6000. Transformation frequencies of over 500 transformants per micrograms of DNA per 1 x 10(6) protoplasts were obtained. Plasmid pCM54 appears to be transmitted in Phytophthora spp. as an extra-chromosomal element through replication, as shown by Southern blot hybridization and by the loss of plasmid methylation. In addition, transformed strains retained their capacity of infecting Serrano pepper seedlings and Mc. Intosh apple fruits, the host plants for P.capsici and P.parasitica, respectively.

  3. BABA and Phytophthora nicotianae Induce Resistance to Phytophthora capsici in Chile Pepper (Capsicum annuum)

    PubMed Central

    Stamler, Rio A.; Holguin, Omar; Dungan, Barry; Schaub, Tanner; Sanogo, Soumaila; Goldberg, Natalie; Randall, Jennifer J.

    2015-01-01

    Induced resistance in plants is a systemic response to certain microorganisms or chemicals that enhances basal defense responses during subsequent plant infection by pathogens. Inoculation of chile pepper with zoospores of non-host Phytophthora nicotianae or the chemical elicitor beta-aminobutyric acid (BABA) significantly inhibited foliar blight caused by Phytophthora capsici. Tissue extract analyses by GC/MS identified conserved change in certain metabolite concentrations following P. nicotianae or BABA treatment. Induced chile pepper plants had reduced concentrations of sucrose and TCA cycle intermediates and increased concentrations of specific hexose-phosphates, hexose-disaccharides and amino acids. Galactose, which increased significantly in induced chile pepper plants, was shown to inhibit growth of P. capsici in a plate assay. PMID:26020237

  4. Pathogenicity of Phytophthora species isolated from rhizosphere soil in the eastern United States

    Treesearch

    Y. Balci; S. Balci; W.L. MacDonald; K.W. Gottschalk

    2008-01-01

    Pathogenicity of seven Phytophthora species was assessed by inoculation of stem and foliar tissues of oak species (Quercus spp.) native to the eastern United States. Phytophthora cambivora, P. cinnamomi, P. citricola, P. europaea, P. quercina...

  5. Testing and implementing methods for managing Phytophthora root diseases in California native habitats and restoration sites

    Treesearch

    Tedmund J. Swiecki; Elizabeth A. Bernhardt

    2017-01-01

    Over the past 14 years, a variety of native plant communities in northern California have been identified where introduced root-rotting Phytophthora species, most notably Phytophthora cinnamomi, P. cambivora, and P. cactorum, are causing decline and mortality of...

  6. Phytophthora Resistance of Soybean Germplasm with High Potential for Asian Soybean Rust Resistance

    USDA-ARS?s Scientific Manuscript database

    Multiple disease resistance is an important component of production agriculture. Major challenges include resistance to Phytophthora root rot caused by evolving Phytophthora sojae races and the recently introduced invasive Asian soybean rust (ASBR) caused by Phakopsora pachyrhizi. The diseases cause...

  7. Biocontrol of Phytophthora Blight and Anthracnose in Pepper by Sequentially Selected Antagonistic Rhizobacteria against Phytophthora capsici.

    PubMed

    Sang, Mee Kyung; Shrestha, Anupama; Kim, Du-Yeon; Park, Kyungseok; Pak, Chun Ho; Kim, Ki Deok

    2013-06-01

    We previously developed a sequential screening procedure to select antagonistic bacterial strains against Phytophthora capsici in pepper plants. In this study, we used a modified screening procedure to select effective biocontrol strains against P. capsici; we evaluated the effect of selected strains on Phytophthora blight and anthracnose occurrence and fruit yield in pepper plants under field and plastic house conditions from 2007 to 2009. We selected four potential biocontrol strains (Pseudomonas otitidis YJR27, P. putida YJR92, Tsukamurella tyrosinosolvens YJR102, and Novosphingobium capsulatum YJR107) among 239 bacterial strains. In the 3-year field tests, all the selected strains significantly (P < 0.05) reduced Phytophthora blight without influencing rhizosphere microbial populations; they showed similar or better levels of disease suppressions than in metalaxyl treatment in the 2007 and 2009 tests, but not in the 2008 test. In the 2-year plastic house tests, all the selected strains significantly (P < 0.05) reduced anthracnose incidence in at least one of the test years, but their biocontrol activities were variable. In addition, strains YJR27, YJR92, and YJR102, in certain harvests, increased pepper fruit numbers in field tests and red fruit weights in plastic house tests. Taken together, these results indicate that the screening procedure is rapid and reliable for the selection of potential biocontrol strains against P. capsici in pepper plants. In addition, these selected strains exhibited biocontrol activities against anthracnose, and some of the strains showed plant growth-promotion activities on pepper fruit.

  8. Biocontrol of Phytophthora Blight and Anthracnose in Pepper by Sequentially Selected Antagonistic Rhizobacteria against Phytophthora capsici

    PubMed Central

    Sang, Mee Kyung; Shrestha, Anupama; Kim, Du-Yeon; Park, Kyungseok; Pak, Chun Ho; Kim, Ki Deok

    2013-01-01

    We previously developed a sequential screening procedure to select antagonistic bacterial strains against Phytophthora capsici in pepper plants. In this study, we used a modified screening procedure to select effective biocontrol strains against P. capsici; we evaluated the effect of selected strains on Phytophthora blight and anthracnose occurrence and fruit yield in pepper plants under field and plastic house conditions from 2007 to 2009. We selected four potential biocontrol strains (Pseudomonas otitidis YJR27, P. putida YJR92, Tsukamurella tyrosinosolvens YJR102, and Novosphingobium capsulatum YJR107) among 239 bacterial strains. In the 3-year field tests, all the selected strains significantly (P < 0.05) reduced Phytophthora blight without influencing rhizosphere microbial populations; they showed similar or better levels of disease suppressions than in metalaxyl treatment in the 2007 and 2009 tests, but not in the 2008 test. In the 2-year plastic house tests, all the selected strains significantly (P < 0.05) reduced anthracnose incidence in at least one of the test years, but their biocontrol activities were variable. In addition, strains YJR27, YJR92, and YJR102, in certain harvests, increased pepper fruit numbers in field tests and red fruit weights in plastic house tests. Taken together, these results indicate that the screening procedure is rapid and reliable for the selection of potential biocontrol strains against P. capsici in pepper plants. In addition, these selected strains exhibited biocontrol activities against anthracnose, and some of the strains showed plant growth-promotion activities on pepper fruit. PMID:25288942

  9. Evaluation of Actigard and Fungicides for Managing Phytophthora Fruit Rot of Watermelon, 2010

    USDA-ARS?s Scientific Manuscript database

    Phytophthora fruit rot caused by Phytophthora capsici is an emerging disease in most watermelon producing regions of Southeast U.S., and has been considered as a top research priority by the National Watermelon Association (NWA). Managing Phytophthora fruit rot can be difficult because of the l...

  10. Effect of Plant Sterols and Tannins on Phytopthora ramorum growth and sporulations. 4th Sudden Oak Death Science Symposium.

    USDA-ARS?s Scientific Manuscript database

    Phytopthora ramorum populations are clonal and consist of three clonal lineages. EU1 is the only lineage found in Europe with a few isolated nursery infections in the USA, NA1 is associated with natural infestations in California and Oregon as well as some nursery infections in North America, and NA...

  11. High-Throughput Chemical Screening Identifies Compounds that Inhibit Different Stages of the Phytophthora agathidicida and Phytophthora cinnamomi Life Cycles

    PubMed Central

    Lawrence, Scott A.; Armstrong, Charlotte B.; Patrick, Wayne M.; Gerth, Monica L.

    2017-01-01

    Oomycetes in the genus Phytophthora are among the most damaging plant pathogens worldwide. Two important species are Phytophthora cinnamomi, which causes root rot in thousands of native and agricultural plants, and Phytophthora agathidicida, which causes kauri dieback disease in New Zealand. As is the case for other Phytophthora species, management options for these two pathogens are limited. Here, we have screened over 100 compounds for their anti-oomycete activity, as a potential first step toward identifying new control strategies. Our screening identified eight compounds that showed activity against both Phytophthora species. These included five antibiotics, two copper compounds and a quaternary ammonium cation. These compounds were tested for their inhibitory action against three stages of the Phytophthora life cycle: mycelial growth, zoospore germination, and zoospore motility. The inhibitory effects of the compounds were broadly similar between the two Phytophthora species, but their effectiveness varied widely among life cycle stages. Mycelial growth was most successfully inhibited by the antibiotics chlortetracycline and paromomycin, and the quaternary ammonium salt benzethonium chloride. Copper chloride and copper sulfate were most effective at inhibiting zoospore germination and motility, whereas the five antibiotics showed relatively poor zoospore inhibition. Benzethonium chloride was identified as a promising antimicrobial, as it is effective across all three life cycle stages. While further testing is required to determine their efficacy and potential phytotoxicity in planta, we have provided new data on those agents that are, and those that are not, effective against P. agathidicida and P. cinnamomi. Additionally, we present here the first published protocol for producing zoospores from P. agathidicida, which will aid in the further study of this emerging pathogen. PMID:28769905

  12. High-Throughput Chemical Screening Identifies Compounds that Inhibit Different Stages of the Phytophthora agathidicida and Phytophthora cinnamomi Life Cycles.

    PubMed

    Lawrence, Scott A; Armstrong, Charlotte B; Patrick, Wayne M; Gerth, Monica L

    2017-01-01

    Oomycetes in the genus Phytophthora are among the most damaging plant pathogens worldwide. Two important species are Phytophthora cinnamomi, which causes root rot in thousands of native and agricultural plants, and Phytophthora agathidicida, which causes kauri dieback disease in New Zealand. As is the case for other Phytophthora species, management options for these two pathogens are limited. Here, we have screened over 100 compounds for their anti-oomycete activity, as a potential first step toward identifying new control strategies. Our screening identified eight compounds that showed activity against both Phytophthora species. These included five antibiotics, two copper compounds and a quaternary ammonium cation. These compounds were tested for their inhibitory action against three stages of the Phytophthora life cycle: mycelial growth, zoospore germination, and zoospore motility. The inhibitory effects of the compounds were broadly similar between the two Phytophthora species, but their effectiveness varied widely among life cycle stages. Mycelial growth was most successfully inhibited by the antibiotics chlortetracycline and paromomycin, and the quaternary ammonium salt benzethonium chloride. Copper chloride and copper sulfate were most effective at inhibiting zoospore germination and motility, whereas the five antibiotics showed relatively poor zoospore inhibition. Benzethonium chloride was identified as a promising antimicrobial, as it is effective across all three life cycle stages. While further testing is required to determine their efficacy and potential phytotoxicity in planta, we have provided new data on those agents that are, and those that are not, effective against P. agathidicida and P. cinnamomi. Additionally, we present here the first published protocol for producing zoospores from P. agathidicida, which will aid in the further study of this emerging pathogen.

  13. Two new Phytophthora species from South African Eucalyptus plantations.

    PubMed

    Maseko, Bongani; Burgess, Treena I; Coutinho, Teresa A; Wingfield, Michael J

    2007-11-01

    A recent study to determine the cause of collar and root rot disease outbreaks of cold tolerant Eucalyptus species in South Africa resulted in the isolation of two putative new Phytophthora species. Based on phylogenetic comparisons using the ITS and beta-tubulin gene regions, these species were shown to be distinct from known species. These differences were also supported by robust morphological characteristics. The names, Phytophthora frigida sp. nov. and Phytophthora alticola sp. nov. are thus provided for these taxa, which are phylogenetically closely related to species within the ITS clade 2 (P. citricola, P. tropicali and P.multivesiculata) and 4 (P. arecae and P. megakarya), respectively. Phytophthora frigida is heterothallic, and produces stellate to rosaceous growth patterns on growth medium, corraloid hyphae, sporangia with a variety of distorted shapes and has the ability to grow at low temperatures. Phytophthora alticola is homothallic and has a slower growth rate in culture. Both P. frigida and P. alticola are pathogenic to Eucalyptus dunnii. In pathogenicity tests, they were, however, less pathogenic than P. cinnamomi, which is a well-known pathogen of Eucalyptus in South Africa.

  14. Development of a pest risk analysis for Phytophthora ramorum for the European Union; the key deliverable from the EU-Funded project RAPRA

    Treesearch

    Claire Sansford; Alan Inman; Joan Webber

    2010-01-01

    Pest Risk Analysis (PRA) is an internationally recognized, structured process of determining whether plant pests and pathogens that are absent from a country or area could enter, establish, and cause an economic or environmental risk that is deemed unacceptable. PRA is also used to help identify phytosanitary measures to reduce risks to an acceptable level. United...

  15. Source or Sink? The Role of Soil and Water Borne Inoculum in the Dispersal of Phytophthora ramorum in Oregon Tanoak Forests

    Treesearch

    E. Peterson; E. Hansen; J. Hulbert

    2014-01-01

    Management of invasive species requires confidence in the detection methods used to assess expanding distributions, as well as an understanding of the dominant modes of spread. Lacking this basic biological information, during early stages of invasion management choices are often driven by available resources and the biology of closely related species. Such has been...

  16. Effect of oomatistatic Compounds and biological control agents on prodcuction of inoculum and root colonization of plants infected with Phytophthora ramorum

    Treesearch

    Nina Shishkoff

    2013-01-01

    In this study, viburnum (Viburnum) cuttings were treated with oomatistats (Subdue Maxx®, Banol®, and Aliette®) at standard rates for use as soil drenches or with biological control organisms (Streptomyces lydicus formulated as Actinovate SP® and used as a soil drench, and Trichoderma...

  17. A molecular method to assess Phytophthora diversity in environmental samples.

    PubMed

    Scibetta, Silvia; Schena, Leonardo; Chimento, Antonio; Cacciola, Santa O; Cooke, David E L

    2012-03-01

    Current molecular detection methods for the genus Phytophthora are specific to a few key species rather than the whole genus and this is a recognized weakness of protocols for ecological studies and international plant health legislation. In the present study a molecular approach was developed to detect Phytophthora species in soil and water samples using novel sets of genus-specific primers designed against the internal transcribed spacer (ITS) regions. Two different rDNA primer sets were tested: one assay amplified a long product including the ITS1, 5.8S and ITS2 regions (LP) and the other a shorter product including the ITS1 only (SP). Both assays specifically amplified products from Phytophthora species without cross-reaction with the related Pythium s. lato, however the SP assay proved the more sensitive and reliable. The method was validated using woodland soil and stream water from Invergowrie, Scotland. On-site use of a knapsack sprayer and in-line water filters proved more rapid and effective than centrifugation at sampling Phytophthora propagules. A total of 15 different Phytophthora phylotypes were identified which clustered within the reported ITS-clades 1, 2, 3, 6, 7 and 8. The range and type of the sequences detected varied from sample to sample and up to three and five different Phytophthora phylotypes were detected within a single sample of soil or water, respectively. The most frequently detected sequences were related to members of ITS-clade 6 (i.e. P. gonapodyides-like). The new method proved very effective at discriminating multiple species in a given sample and can also detect as yet unknown species. The reported primers and methods will prove valuable for ecological studies, biosecurity and commercial plant, soil or water (e.g. irrigation water) testing as well as the wider metagenomic sampling of this fascinating component of microbial pathogen diversity.

  18. Transformation of the oomycete pathogen, Phytophthora infestans.

    PubMed

    Judelson, H S; Tyler, B M; Michelmore, R W

    1991-01-01

    A stable transformation procedure has been developed for Phytophthora infestans, an oomycete fungus that causes the late blight diseases of potato and tomato. This is the first description of reliable methods for transformation in an oomycete pathogen. Drug-resistant transformants were obtained by using vectors that contained bacterial genes for resistance to hygromycin B or G418 fused to promoters and terminators from the Hsp70 and Ham34 genes of the oomycete, Bremia lactucae. Using polyethylene glycol and CaCl2, vector DNA was introduced into protoplasts as a complex with cationic liposomes or with carrier DNA only. Transformants were obtained at similar frequencies with each combination of promoter and selectable marker and were confirmed by DNA and RNA hybridization and phosphotransferase assays. Transformation occurred through the integration of single or tandemly repeated copies of the plasmids into genomic DNA, conferring mitotically stable drug-resistant phenotypes. The sizes of the marker gene mRNAs in each transformant and the results of transcript mapping studies were consistent with the function of the B. lactucae regulatory sequences in P. infestans. A hygromycin-resistant transformant was tested and found to maintain pathogenicity, indicating that the gene transfer procedure will be useful for the molecular analysis of genes relevant to disease.

  19. A unique species in Phytophthora clade 10, Phytophthora intercalaris sp. nov., recovered from stream and irrigation water in the eastern USA

    PubMed Central

    Balci, Y.; Brazee, N. J.; Loyd, A. L.; Hong, C. X.

    2016-01-01

    A novel species of the genus Phytophthora was recovered during surveys of stream and nursery irrigation water in Maryland, Massachusetts, North Carolina, Virginia and West Virginia in the USA. The novel species is heterothallic, and all examined isolates were A1 mating type. It produced rare ornamented oogonia and amphigynous antheridia when paired with A2 mating type testers of Phytophthora cinnamomi and Phytophthora cryptogea. Sporangia of this novel species were non-papillate and non-caducous. Thin-walled intercalary chlamydospores were abundant in hemp seed agar and carrot agar, while they were produced only rarely in aged cultures grown in clarified V8 juice agar. Phylogenetic analyses based on sequences of the internal transcribed spacer region and the β-tubulin and mitochondrial cytochrome-c oxidase 1 (cox1) genes indicated that the novel species is phylogenetically close to Phytophthora gallica in Phytophthora clade 10. The novel species has morphological and molecular features that are distinct from those of other species in Phytophthora clade 10. It is formally described here as Phytophthora intercalaris sp. nov. Description of this unique clade-10 species is important for understanding the phylogeny and evolution of Phytophthora clade 10. PMID:26620125

  20. The Effect of Potassium Nitrate on the Reduction of Phytophthora Stem Rot Disease of Soybeans, the Growth Rate and Zoospore Release of Phytophthora Sojae

    USDA-ARS?s Scientific Manuscript database

    The effects of potassium nitrate (KNO3) application on Phytophthora stem rot disease reduction of Glycine max (L.) Merr. cvs. Chusei-Hikarikuro and Sachiyutaka, and fungal growth and zoospore release of a Phytophthora sojae isolate were investigated under laboratory conditions. The application of 4-...