@article {EFP:EFP167, title = {Pathogenicity of Phytophthora species to Pacific Northwest conifers}, journal = {European Journal of Forest Pathology}, volume = {12}, number = {3}, year = {1982}, pages = {167{\textendash}174}, publisher = {Blackwell Publishing Ltd}, abstract = {

Phytophthora root rot is described for the first time killing sugar pine (Pinus lambertiana) in a seed orchard and four species of true fir (Abies spp.) in a forest nursery. P. cactorum was recovered from true firs and P. megasperma was recovered from sugar pine. P. cryptogea was recovered from sugar pine and true fir but isolates from the two locations differed from each other in pathogenicity and colony appearance. Isolates recovered from these hosts and isolates of 6 Phytophthora species previously recovered from Douglas-fir (Pseudotsuga menziesii) were then tested for pathogenicity on seedlings of 9 Northwest conifers. P. megasperma Group 1, P. cryptogea, and P. cinnamomi were pathogenic to all tree species except western redcedar (Thujaplicata). Western hemlock (Tsuga heterophylla) and true firs were susceptible to most species tested; ponderosa (P. ponderosa) and sugar pines were damaged only by P. cryptogea and P. cinnamomi; western redcedar was resistant to all isolates.

}, issn = {1439-0329}, doi = {10.1111/j.1439-0329.1982.tb01390.x}, url = {http://dx.doi.org/10.1111/j.1439-0329.1982.tb01390.x}, author = {P.B. Hamm and Hansen, E.M.} } @article {654, title = {Phytophthora pseudotsugae, a new species causing root rot of Douglas-fir}, journal = {Can. J. Bot.}, volume = {61}, year = {1983}, pages = {2626{\textendash}2631}, abstract = {

Phytophthora pseudotsugae n. sp. was isolated from rotted roots of Douglas-fir growing in forest tree nurseries in Oregon and Washington. It is distinguished by large oogonia and oospores, mostly paragynous antheridia, and predominantly spherical or ovoid, persistent sporangia borne primarily on simple and unbranched sporangiophores. Sporangia are formed occasionally in liquid culture, rarely in solid media. Phytophthora pseudotsugae is distinguished most readily from P. cactorum by its unbranched sporangiophores and persistent sporangia. It also differs in growth on defined media, electrophoretic protein patterns, and pathogenicity. Comparison is also made with P. iranica, the other species in group 1 of Waterhouse.

}, doi = {10.1139/b83-289}, url = {http://rparticle.web-p.cisti.nrc.ca/rparticle/AbstractTemplateServlet?calyLang=eng\&journal=cjb\&volume=61\&year=1983\&issue=10\&msno=b83-289}, author = {P.B. Hamm and Hansen, E.M.} } @article {200, title = {Improved method for isolating Phytophthora lateralis from soil.}, journal = {Plant disease}, volume = {68}, year = {1984}, month = {June 1984}, pages = {517-519}, issn = {01912917}, doi = {10.1094/PD-68-517}, author = {P.B. Hamm and Hansen, E.M.} } @article {hamm1987identification, title = {Identification of Phytophthora spp. known to attack conifers in the Pacific Northwest}, journal = {Northwest Sci.}, volume = {61}, year = {1987}, month = {1987}, pages = {103-109}, publisher = {WSU Press}, author = {P.B. Hamm and Hansen, E.M.} } @article {EverettM.Hansen01012009, title = {Phytophthora rosacearum and P. sansomeana, new species segregated from the Phytophthora megasperma "complex"}, journal = {Mycologia}, volume = {101}, number = {1}, year = {2009}, pages = {129-135}, abstract = {

Phytophthora megasperma sensu lato was a conglomeration of morphologically similar but phylogenetically unrelated species. In this paper we continue the segregation of species from the old P. megasperma complex, formally naming two previously recognized isolate groups. Isolates recovered from rosaceous fruit trees (especially apple and cherry) are in ITS clade 6, related to but distinct from P. megasperma sensu strictu. They are named here Phytophthora rosacearum. They have been referred to previously as the "AC" or "high temperature small oospore" group of P. megasperma. A second group of isolates, earlier called "soybean race non-classifiable", recovered from soybeans in Indiana and other Midwestern states, are morphologically similar to P. megasperma sensu strictu but unrelated to that species, falling in ITS clade 8. They are named here P. sansomeana. Isolates recovered from Douglas-fir seedlings in nurseries in the Pacific Northwest and various weedy hosts in New York State, referred to in earlier work as "P. megasperma DF1", appear to be conspecific with the soybean isolates, although they include certain ITS DNA polymorphisms. Both new species are supported by a combination of new and previously published morphological, growth and molecular data.

}, doi = {10.3852/07-203}, url = {http://www.mycologia.org/cgi/content/abstract/101/1/129}, author = {Hansen, Everett M. and Wilcox, Wayne F. and Reeser, Paul W. and Sutton, Wendy} } @article {hansen1979isolation, title = {Isolation, incidence and management of Phytophthora in forest tree nurseries in the Pacific Northwest [USA]}, journal = {Plant Disease Reporter}, volume = {63}, year = {1979}, pages = {607-611}, issn = {0032-0811}, author = {Hansen, E.M. and P.B. Hamm and Julis, AJ and L.F. Roth} } @article { refId, title = {Phytophthora species in oak forests of north-east France}, journal = {Ann. For. Sci.}, volume = {56}, number = {7}, year = {1999}, pages = {539-547}, abstract = {

Phytophthora species were surveyed from the end of 1997 through July 1998 in oak forests in NE France. Healthy (Amance) or declining (Illwald) forests were compared. The Phytophthora population in both was diverse and locally abundant. At least eight species were present at Amance and six at Illwald. At Amance Phytophthora species had a localized distribution in water and low-lying soils. At Illwald distribution was more uniform apparently due to flooding events. Most often recovered were P. citricola, P. gonapodyides and P. quercina. P. gonapodyides was ubiquitous in water and colonized leaf debris. P. quercina was widely distributed in soil but not abundant, and was found in sites that did not otherwise appear to favor Phytophthora. No correlation was detected between presence of Phytophthora in soil and health of trees. Unusual combinations of environmental factors may be required for resident Phytophthora to have a detrimental impact on oaks. {\textcopyright} 1999 Editions scientifiques et m{\'e}dicales Elsevier SAS.

}, doi = {10.1051/forest:19990702}, url = {http://dx.doi.org/10.1051/forest:19990702}, author = {Hansen, E.M. and Delatour, Claude} } @article {4655, title = {First Confirmation of Phytophthora lateralis in Europe}, journal = {Plant Disease}, volume = {83}, year = {1999}, month = {Jan-06-1999}, pages = {587 - 587}, abstract = {

Phytophthora lateralis, a pathogen of Chamaecyparis lawsoniana (Port-Orford cedar or Lawson{\textquoteright}s cypress), was confirmed in France, but isolates from Germany identified as P. lateralis or {\textquotedblleft}similar to{\textquotedblright} P. lateralis proved to be P. gonapodyides. Previously, P. lateralis was known only from western North America, where it has been destructive in nurseries, ornamental plantings, and the forest since its introduction about 1920 (1). Reports from other locations have proved to be misidentifications or impossible to confirm. In France, P. lateralis was isolated and identified from C. lawsoniana on two occasions (1996 and 1998) in different parts of the country, probably stemming from a single original infestation of young, potted, greenhouse-propagated cedars in a commercial nursery. German isolates were from an old culture collection and from irrigation water in a nursery growing a wide range of woody ornamentals. Identifications were confirmed by comparison (2) with authentic isolates. P. lateralis isolates from France and Oregon formed laterally proliferating, elongated obpyriform sporangia that under the conditions of our tests could be dislodged by agitation, leaving a short pedicel. Also, brown chlamydospores formed laterally on the hyphae or terminally on a short stalk and oospores were not formed on standard media. Radial growth was about 2 mm per day. In contrast, sporangia of German isolates and known P. gonapodyides isolates were similar. They exhibited nested pro liferation, were broader than P. lateralis sporangia, and were not readily dehiscent. Some P. gonapodyides isolates, including those from Germany, formed chlamydospores, but these were nearly all catenulate and not lateral, and isolates grew faster (3 to 4 mm per day). Pathogenicity was tested by stem inoculation of C. lawsoniana. P. lateralis from France and Oregon produced lesions averaging 4.7 cm after 2 months (range 2.0 to 8.1 cm, six replicates per isolate, five isolates) while the six replicates of the two German isolates averaged 1.2- and 1.6-cm lesion lengths. Furthermore, sequences of internal transcribed spacer (ITS) DNA from French and Oregon P. lateralis isolates were identical, while sequences of German isolates were similar to P. gonapodyides (J. Duncan and D. Cooke, personal communiation). P. lateralis is a dangerous pathogen of C. lawsoniana and is also pathogenic to Taxus spp. (1), although less aggressive on this host. If established, it would be a serious threat to the widespread ornamental plantings and scattered forest plantations of C. lawsoniana in Europe.

}, issn = {0191-2917}, doi = {10.1094/PDIS.1999.83.6.587B}, url = {http://apsjournals.apsnet.org/doi/10.1094/PDIS.1999.83.6.587B}, author = {Hansen, E. M. and Streito, Jean-Claude and Delatour, Claude} } @article {doi:10.1094/PD-89-0063, title = {Susceptibility of Oregon forest trees and shrubs to Phytophthora ramorum: a comparison of artificial inoculation and natural infection}, journal = {Plant Disease}, volume = {89}, number = {1}, year = {2005}, pages = {63-70}, abstract = {

Phytophthora ramorum is an invasive pathogen in some mixed-hardwood forests in California and southwestern Oregon, where it causes sudden oak death (SOD) on some members of Fagaceae, ramorum shoot dieback on some members of Ericaceae and conifers, and ramorum leaf blight on diverse hosts. We compared symptoms of P. ramorum infection resulting from four different artificial inoculation techniques with the symptoms of natural infection on 49 western forest trees and shrubs; 80\% proved susceptible to one degree or another. No single inoculation method predicted the full range of symptoms observed in the field, but whole plant dip came closest. Detached-leaf-dip inoculation provided a rapid assay and permitted a reasonable assessment of susceptibility to leaf blight. Both leaf age and inoculum dose affected detached-leaf assays. SOD and dieback hosts often developed limited leaf symptoms, although the pattern of midrib and petiole necrosis was distinctive. Stem-wound inoculation of seedlings correlated with field symptoms for several hosts. The results suggested that additional conifer species may be damaged in the field. Log inoculation provided a realistic test of susceptibility to SOD, but was cumbersome and subject to seasonal variability. Pacific rhododendron, salmonberry, cascara, and poison oak were confirmed as hosts by completing Koch{\textquoteright}s postulates. Douglas-fir was most susceptible to shoot dieback shortly after budburst, with infection occurring at the bud.

}, doi = {10.1094/PD-89-0063}, url = {http://apsjournals.apsnet.org/doi/abs/10.1094/PD-89-0063}, author = {Hansen, E.M. and Parke, J. L. and Sutton, W.} } @article {3992, title = {Phytophthora beyond agriculture}, journal = {Annual Review of Phytopathology}, volume = {50}, year = {2012}, month = {09/2012}, pages = {359 - 378}, abstract = {

Little is known about indigenous Phytophthora species in natural ecosystems. Increasing evidence, however, suggests that a diverse, trophically complex Phytophthora community is important in many forests. The number of described species has steadily increased, with a dramatic spike in recent years as new species have been split from old and new species have been discovered through exploration of new habitats. Forest soil, streams, and the upper canopies of trees are now being explored for Phytophthora diversity, and a new appreciation for the ecological amplitude of the genus is emerging. Ten to twenty species are regularly identified in temperate forest surveys. Half or more of this Phytophthora diversity comes from species described since 2000. Taxa in internal transcribed spacer (ITS) Clade 6 are especially numerous in forest streams and may be saprophytic in this habitat. Three ecological assemblages of forest Phytophthora species are hypothesized: aquatic opportunists, foliar pathogens, and soilborne fine-root and canker pathogens. Aggressive invasive species are associated with all three groups.

}, issn = {0066-4286}, doi = {10.1146/annurev-phyto-081211-172946}, url = {http://www.annualreviews.org/doi/pdf/10.1146/annurev-phyto-081211-172946}, author = {Hansen, Everett M. and Reeser, Paul W. and Sutton, Wendy} } @article {361, title = {Species of the Phytophthora megasperma complex}, journal = {Mycologia,}, volume = {83}, year = {1991}, month = {May - Jun., 1991}, pages = {376-381}, issn = {00275514}, url = {http://www.jstor.org/stable/3759999}, author = {Hansen, E.M. and D. P. Maxwell} } @article {Hansen1986557, title = {The taxonomic structure of Phytophthora megasperma: Evidence for emerging biological species groups}, journal = {Transactions of the British Mycological Society}, volume = {87}, number = {4}, year = {1986}, pages = {557 - 573}, abstract = {

Nomenclatural uncertainty surrounds P. megasperma as various authors, working with limited groups of isolates, offer their interpretations of this species based on pathology, morphology, or cytology. We compared 93 isolates, including many described by others, for classical morphological features, growth behaviour and appearance, electrophoretic pattern of total proteins, chromosome number and nuclear DNA content. Nine distinct sub-groups were distinguished. While most groups could be distinguished by each of the criteria, protein electrophoresis was the most sensitive. The groups included: ALF, pathogenic to alfalfa, n = 12{\textendash}15; SOY, pathogenic to soybean, n = 12{\textendash}15; CLO, pathogenic to clover, n = 11{\textendash}15; DF, pathogenic to Douglas fir, n = 17{\textendash}24; AC, isolated from rosaceous fruit trees; and BHR, a major group obtained from a broad range of hosts. The last two groups, distinguished primarily by protein pattern, comprised at least four karyotypes: KI, n = 12{\textendash}17; KII, n = 15{\textendash}23; KIII, n = 22{\textendash}28; and KIV, n= 26{\textendash}34. All four karyotypes occur within the BHR protein group, suggesting a polyploid series within a closely related genotype.

Two broad lines of evolution are hypothesized, a legume line comprising ALF, SOY, CLO, and perhaps DF isolates, and a Broad Host Range line of AC and BHR isolates. Sub-groups within each line may represent emerging biological species, isolated by host specificity or karyotype. Taxonomic designation for the various groups must await confirmation of the hypothesis by demonstration of the extent of barriers to gene flow between the groups.

}, issn = {0007-1536}, doi = {10.1016/S0007-1536(86)80097-3}, url = {http://www.sciencedirect.com/science/article/pii/S0007153686800973}, author = {Hansen, E.M. and C.M. Brasier and D.S. Shaw and P.B. Hamm} } @article {4654, title = {Phytophthora species in oak forests of north-east France}, journal = {ANNALS OF FOREST SCIENCE}, volume = {56}, year = {1999}, month = {Jan-01-1999}, pages = {539 - 547}, abstract = {

Phytophthora species were surveyed from the end of 1997 through July 1998 in oak forests in NE France. Healthy (Amance) or declining (Illwald) forests were compared. The Phytophthora population in both was diverse and locally abundant. At least eight species were present at Amance and six at Illwald. At Amance Phytophthora species had a localized distribution in water and low-lying soils. At Illwald distribution was more uniform apparently due to flooding events. Most often recovered were P. citricola, P. gonapodyides and P. quercina. P. gonapodyides was ubiquitous in water and colonized leaf debris. P. quercina was widely distributed in soil but not abundant, and was found in sites that did not otherwise appear to favor Phytophthora. No correlation was detected between presence of Phytophthora in soil and health of trees. Unusual combinations of environmental factors may be required for resident Phytophthora to have a detrimental impact on oaks. {\textcopyright} 1999 Editions scientifiques et m{\'e}dicales Elsevier SAS.

}, issn = {0003-4312}, doi = {10.1051/forest:19990702}, url = {http://www.afs-journal.org/10.1051/forest:19990702}, author = {Hansen, Everett and Delatour, Claude} } @article {doi:10.1094/PDIS.1999.83.6.587B, title = {First confirmation of Phytophthora lateralis in Europe}, journal = {Plant Disease}, volume = {83}, number = {6}, year = {1999}, pages = {587-587}, doi = {10.1094/PDIS.1999.83.6.587B}, url = {http://apsjournals.apsnet.org/doi/abs/10.1094/PDIS.1999.83.6.587B}, author = {Hansen, E.M. and Streito, Jean-Claude and Delatour, Claude} } @article {hansen1996survival, title = {Survival of Phytophthora lateralis in infected roots of Port Orford cedar}, journal = {Plant Disease}, volume = {80}, number = {9}, year = {1996}, pages = {1075{\textendash}1078}, publisher = {[St. Paul, Minn.: American Phytopathological Society], 1980-}, issn = {0191-2917}, author = {Hansen, E.M. and P.B. Hamm} } @article {360, title = {Phytophthora nemorosa, a new species causing cankers and leaf blight of forest trees in California and Oregon, U.S.A.}, journal = {Mycotaxon}, volume = {88}, year = {2003}, pages = {129{\textendash}138}, abstract = {

Phytophthora nemorosa, a new species isolated from stem cankers on two species of Fagaceae and leaves of various hosts, is described. The new species resembles P. ilicis with homothallic, amphigynous antheridia and deciduous, semi-papillate sporangia, and has a related ITS-DNA sequence. Symptoms and host range are similar to P. ramorum, cause of Sudden Oak Death and leaf blight and shoot dieback diseases in California and Oregon forests, although P. nemorosa does not appear to cause wide-spread mortality of oak trees.

}, keywords = {Lithocarpus densiflorus, Phytophthora ilicis, Phytophthora ramorum, Quercus agrifolia, Umbellularia californica}, url = {http://www.mycotaxon.com/vol/abstracts/88/88-129.html}, author = {Hansen, E.M. and P. Reeser and J. M. Davidson and Garbelotto, M. and K. Ivors and L. Douhan and D. M. Rizzo} } @article {4633, title = {Redesignation of Phytophthora taxon Pgchlamydo as Phytophthora chlamydospora sp. nov.}, journal = {North American Fungi}, volume = {10}, year = {2015}, pages = {1{\textendash}14}, abstract = {

A new species, Phytophthora chlamydospora, is described. P. chlamydospora, previously known informally as P. taxon Pgchlamydo, is found in streams and wet soil worldwide and is a pathogen of some riparian tree species. It is self-sterile, and produces persistent non-papillate sporangia, usually on unbranched sporangiophores. Clamydospores are formed most regularly at warmer temperatures. Phytophthora chlamydospora is classified in ITS Clade 6.

}, keywords = {chlamydospora, new species, Pg chlamydo, Phytophthora, soil, streams}, issn = {1937-786X}, url = {https://www.pnwfungi.org/index.php/pnwfungi/article/view/1414}, author = {Everett Hansen and Paul Reeser and Wendy Sutton and Clive Brasier} } @article {657, title = {Survival, spread, and pathogenicity of Phytophthora spp. on Douglas-fir seedlings planted on forest sites.}, journal = {Phytopathology 70:}, volume = {70}, year = {1980}, pages = {422-425}, abstract = {

Douglas-fir seedling stock infected in the nursery with Phytophthora cryptogea, P. drechsleri, P. megasperma, P. cactorum, and an unidentified Phytophthora sp. were outplanted on commercial forest sites to test survival of the diseased trees and of the pathogens. Mortality of trees initially classified in severe, moderate, and inconspicuous symptom classes at outplanting reached 61, 26, and 11\%, respectively, after 18 mo. Phytophthora was recovered about equally from roots of trees in each symptom class (15, 13, and 12\%). Surviving trees regenerated healthy roots above old lesions even though Phytophthora persisted. Disease spread was limited. None of 360 healthy trees planted 0.6 m downslope from diseased trees became infected, and only 2 of 720 healthy trees became infected after each was paired with a diseased tree in the same planting hole.

}, doi = {10.1094/Phyto-70-422}, url = {http://www.apsnet.org/publications/phytopathology/backissues/Documents/1980Abstracts/Phyto70_422.htm}, author = {Hansen, E.M. and L.F. Roth and P.B. Hamm and A. J. Julis.} } @article {4293, title = {First Report of Phytophthora pluvialis Causing Needle Loss and Shoot Dieback on Douglas-fir in Oregon and New Zealand}, journal = {Plant Disease}, volume = {99}, year = {2015}, month = {Jan-05-2015}, pages = {727 - 727}, abstract = {

Douglas-fir (DF, Pseudotsuga menziesii) is the most important forest tree in Oregon and is the second most valuable conifer in New Zealand. Phytophthora pluvialis was described (Reeser et al. 2013) from mixed evergreen forests in southwest Oregon. It was subsequently identified as the cause of red needle cast of radiata pine in New Zealand (Dick et al. 2014). There it was also isolated from chlorotic DF needles that dislodged readily from trees growing close to diseased radiata pine. In spring 2014, raintraps baited with rhododendron leaves were paired with nine 2-year-old DF seedlings at three or four locations in each of three 20- to 30-year-old DF plantations in western Oregon (11 raintraps and 99 seedlings total); control raintraps and seedlings were at two sites with no overstory (two raintraps and 18 seedlings total). Baits were collected at 2-week intervals and plated in corn meal agar (CMA) amended with natamycin, ampicillin, and rifamycin SV (CARP, Reeser et al. 2013). Symptomatic tissues from the seedlings were surface disinfested and plated in CARP. P. pluvialis was identified by sequencing the mitochondrial cox spacer region. Zoospores or sporangia produced from Oregon DF isolate 3661-NDL-041514 (GenBank KM491217) were used to inoculate four 2-year-old DF seedlings. Sporangia were induced by flooding cultures grown in pea broth with filtered stream water; zoospore release was stimulated by chilling. About 20 ml of inoculum was applied to DF seedlings using an airbrush sprayer. Two control seedlings were sprayed with filtered stream water. Inoculum contained 200 to 300 sporangia/ml or 5 {\texttimes} 104 zoospores/ml. Inoculated trees were enclosed in polyethylene bags for 48 h with supplemental mist and incubated in a growth chamber at 16 to 18{\textdegree}C with 12-h photoperiod. Symptomatic tissues were collected starting at 14 days, surface disinfested, and plated in CARP. Isolates were collected and identified as above. P. pluvialis was isolated from baits in nine of the 11 raintraps and from 54\% of seedlings across all three plantations. All isolations from control sites were negative. Overstory trees exhibited thin crowns from needle loss. Symptoms on seedlings included partial needle loss of 1- and 2-year-old needles and irregular mottled needle chlorosis. P. pluvialis was isolated from needles on 54\% of the seedlings associated with positive raintraps. Isolation success from individual symptomatic needles from locations where raintraps were positive was \~{}13\%. Twig symptoms were not visible on overstory trees, but trees were not felled for close examination. Twig symptoms on seedlings included tip dieback and stem lesions extending from bud scars. Twig symptoms developed on 37\% of seedlings from locations with positive raintraps; P. pluvialis was isolated from 47\% of these twig lesions. Needle and twig symptoms similar to those on naturally infected seedlings developed on artificially inoculated seedlings and P. pluvialis was isolated from seedlings inoculated with both sporangia and zoospores, but not from control seedlings. This is the first report of a foliar Phytophthora species on DF. There is as yet little information on epidemiology or impact in the forest in Oregon. In New Zealand, DF defoliation was most evident in plantations growing close to radiata pine plantations on sites prone to red needle cast.

}, issn = {0191-2917}, doi = {10.1094/PDIS-09-14-0943-PDN}, url = {http://apsjournals.apsnet.org/doi/10.1094/PDIS-09-14-0943-PDN}, author = {Hansen, E. M. and Reeser, P. and Sutton, W. and Gardner, J. and Williams, N.} } @article {res2008alien, title = {Alien forest pathogens: Phytophthora species are changing world forests}, journal = {Boreal Env. Res.}, volume = {13}, year = {2008}, pages = {33{\textendash}41}, issn = {1797-2469}, author = {Hansen, E.M.} } @article {doi:10.1094/PDIS.2000.84.1.4, title = {Managing Port-Orford-Cedar and the Introduced Pathogen Phytophthora lateralis}, journal = {Plant Disease}, volume = {84}, number = {1}, year = {2000}, pages = {4-14}, doi = {10.1094/PDIS.2000.84.1.4}, url = {http://apsjournals.apsnet.org/doi/abs/10.1094/PDIS.2000.84.1.4}, author = {Hansen, Everett M. and Goheen, Donald J. and Jules, Erik S. and Ullian, Barbara} } @article {Hansen:1 May 2008:0045-5067:1133, title = {Epidemiology of Phytophthora ramorum in Oregon tanoak forests}, journal = {Canadian Journal of Forest Research}, volume = {38}, year = {Submitted}, pages = {1133-1143(11)}, abstract = {

We followed the local intensification and dispersal of Phytophthora ramorum Werres, De Cock, \& Man In{\textquoteright}t Veld in Oregon tanoak (Lithocarpus densiflorus (Hook \& Arn.) Rehd.) forests from its initial detection in 2001 through 2006, coincident with a continuing eradication effort. The initial infested area included nine scattered sites below 400m elevation, close to the Pacific Ocean near Brookings, Oregon. In subsequent years, one-half of new infections were within 122m of a previous infection, and 79\% of the newly detected trees occurred within 300m of a previously identified tree. Dispersal up to 4km was occasionally recorded. Initial infection occurred in the upper crowns of tanoak trees. The pathogen was recovered in rainwater collected beneath diseased tanoak trees in every month from November 2006 through October 2007. Twenty-four multilocus microsatellite genotypes were identified among 272 P. ramorum isolates collected from Curry County. Genotypic analysis provided independent estimates of time of origin of the Oregon infestation, its clustered distribution, and dispersal distances. In all sampling years, 60\%-71\% of the isolates belonged to the same multilocus genotype. In 2001, 12 genotypes were detected and new genotypes were identified in each of the subsequent years, but all isolates belonged to the same clonal lineage. Knowledge of local intensification of the disease and long-distance dispersal should inform both Oregon eradication efforts and national quarantine regulations.

}, doi = {10.1139/X07-217}, url = {http://www.nrcresearchpress.com/doi/abs/10.1139/X07-217$\#$.UNIUO7aKS0c}, author = {Hansen, E.M. and Kanaskie, A. and Prospero, S and McWilliams, M. and Goheen, E. M. and Osterbauer, N. and P. Reeser and Sutton, W.} } @article {hansen1989testing, title = {Testing Port-Orford-cedar for resistance to Phytophthora.}, journal = {Plant Disease}, volume = {73}, number = {10}, year = {1989}, pages = {791{\textendash}794}, issn = {0191-2917}, author = {Hansen, E.M. and P.B. Hamm and L.F. Roth} } @article {4069, title = {First report of Phytophthora plurivora causing collar rot on common alder in Spain}, journal = {Plant Disease}, volume = {98}, year = {2013}, month = {03/2014}, pages = {425}, abstract = {

Phytophthora decline of riparian alder (Alnus spp.) has been reported in several European countries. Death of common alder (Alnus glutinosa) due to Phytophthora alni has also been reported in Spain. During several surveys of alder trees in September 2012, typical die-back symptoms, including sparse small yellowish foliage and the presence of rusty exudates on the bark at the collar and lower stem were observed in A.glutinosa growing on the banks of the river Tera (Langa de Duero, Soria, 41{\textdegree}36'34"N, 3{\textdegree}25'10"W, elevation 851 m) and the river Tormes (La Maya, Salamanca, 40{\textdegree}41'42"N, 5{\textdegree}35'36"W, elevation 833 m). Bark samples plus cambium were taken from the active lesions at collar region, cut into small pieces, dried on filter paper and plated on V8-PARPH agar. The samples were incubated for four days at 20 {\textdegree}C in the dark before obtaining the Phytophthora isolates. Colonies developed on V8 juice agar (V8A) had limited aerial mycelium at the centre and displayed radiate and slightly chrysanthemum-like growth pattern. Mycelial growth was optimal at 25 {\textdegree}C (radial growth rate, 8.2 mm d-1), whereas no growth was observed at 32 {\textdegree}C. Isolates were homothallic with paragynous antheridia, smooth-walled spherical (very rarely elongated) oogonia (22.8{\textendash}30.6 μm diam.) and both plerotic and aplerotic golden brown oospores (21.3{\textendash}28.5 μm diam.). In non sterile soil extracts, the isolates produced abundant sporangia (31.5{\textendash}57.2 {\texttimes} 21.3{\textendash}38.4 μm; length:breadth ratio 1.2 to 1.6) borne terminally on unbranched or sympodial sporagiophores, occasionally attached laterally to the sporangiophores. Sporagia were non-caducous, semipapillate, mainly ovoid and obpyriform, obovoid to limoniform but sometimes distorted with two apices. On the basis of the morpho-physiological features, the isolates resembled P. plurivora (formerly identified as P. citricola). To confirm this, genomic DNA was extracted and subjected to Polymerase Chain Reaction (PCR). The internal transcribed spacer (ITS) region of the rDNA was amplified using the ITS-6 (5{\textquoteright} GAA GGT GAA GTC GTA ACA AGG 3{\textquoteright}) and ITS-4 (5{\textquoteright} TCC TCC GCT TAT TGA TAT GC 3{\textquoteright}) primers before sequencing (Secugen, Madrid, Spain). The sequences were deposited in the EMBL/GenBank database (GenBank Accession No. KF413074 and KF413075). In order to perform the pathogenicity test, 10 A. glutinosa seedlings (two-year-old) per isolate were inoculated by using the under bark inoculation technique and 10 control seedlings were inoculated with V8A. Seedlings were incubated in a growth chamber at 22.5 {\textordmasculine}C with a 14-h photoperiod. Three months after inoculation, all inoculated plants wilted and died, whereas the control plants showed no disease symptoms. To fulfil Koch{\textquoteright}s postulates, the pathogen was re-isolated from the necrotic lesions developed around inoculation points, thus confirming its pathogenicity. Phytophthora plurivora has been found to be present in rhizosphere soil beneath Alnus spp. and to cause aerial canker and collar rot on alder trees in Austria, Germany and Romania. Further studies and surveys are essential to determine the distribution, extent of damage and potential interactions with other alder pathogens (e.g. P. alni). To our knowledge, this is the first record of P. plurivora affecting A. glutinosa in Spain.

}, issn = {0191-2917}, doi = {10.1094/PDIS-07-13-0784-PDN}, url = {http://dx.doi.org/10.1094/PDIS-07-13-0784-PDN }, author = {Haque, Mohammed Masum Ul and Mart{\'\i}nez-{\'A}lvarez, Pablo and Lomba, {\'e} Mar{\'\i}a and Mart{\'\i}n-Garc{\'\i}a, Jorge and Diez, Julio Javier} } @article {4288, title = {Variation in pathogenicity among the three subspecies of Phytophthora alni on detached leaves, twigs and branches of Alnus glutinosa}, journal = {Forest Pathology}, volume = {45}, year = {2015}, month = {December 2015}, pages = {484{\textendash}491}, abstract = {

Pathogenicity tests were carried out on leaves, twigs and branches of Alnus glutinosa using several isolates of Phytophthora alni ssp. alni, P.\ alni ssp. multiformis and P.\ alni ssp. uniformis in\ vitro. Healthy fresh leaves were collected from disease-free areas and inoculated with mycelium on agar discs or by dipping in zoospore suspensions. In addition, twigs and branches were collected from both disease-free and disease-affected areas, inoculated with mycelium on agar discs and incubated at four temperatures (15, 20, 25, 30{\textdegree}C). All subspecies tested were pathogenic but with varied level of virulence. In inoculation tests on foliage, wounding was a key factor in causing infections: lesions on inoculated wounded leaves were larger than on non-wounded leaves. In the twig and branch inoculation tests, no differences in virulence were observed among the P.\ alni subspecies in terms of sampling locations, but lesions differed in size according to incubation temperature, with the largest lesions occurring on tissues incubated at 25{\textdegree}C. The work is the first to report foliar necrosis caused by P.\ alni on A.\ glutinosa. P.\ alni ssp. uniformis was the least virulent of the subspecies in branch inoculations. These findings demonstrate that various tissues of A.\ glutinosa could act as sources of pathogen inoculum and may disseminate alder Phytophthora in natural ecosystems.

}, doi = {10.1111/efp.12198}, url = {http://doi.wiley.com/10.1111/efp.12198}, author = {Haque, M. M. U. and Mart{\'\i}n-Garc{\'\i}a, J. and Diez, J. J.} } @article {4470, title = {Temporal metabolic profiling of the Quercus suber - Phytophthora cinnamomi system by middle-infrared spectroscopy}, journal = {Forest Pathology}, volume = {46}, year = {2016}, month = {Jan-04-2016}, pages = {122 - 133}, abstract = {

The oomycete Phytophthora cinnamomi is an aggressive plant pathogen, detrimental to many ecosystems including cork oak (Quercus suber) stands, and can inflict great losses in one of the greatest {\textquoteleft}hotspots{\textquoteright} for biodiversity in the world. Here, we applied Fourier transform-infrared (FT-IR) spectroscopy combined with chemometrics to disclose the metabolic patterns of cork oak roots and P.\ cinnamomi mycelium during the early hours of the interaction. As early as 2\ h post-inoculation (hpi), cork oak roots showed altered metabolic patterns with significant variations for regions associated with carbohydrate, glycoconjugate and lipid groups when compared to mock-inoculated plants. These variations were further extended at 8\ hpi. Surprisingly, at 16\ hpi, the metabolic changes in inoculated and mock-inoculated plants were similar, and at 24\ hpi, the metabolic patterns of the regions mentioned above were inverted when compared to samples collected at 8\ hpi. Principal component analysis of the FT-IR spectra confirmed that the metabolic patterns of inoculated cork oak roots could be readily distinguished from those of mock-inoculated plants at 2, 8 and 24\ hpi, but not at 16\ hpi. FT-IR spectral analysis from mycelium of P.\ cinnamomi exposed to cork oak root exudates revealed contrasting variations for regions associated with protein groups at 16 and 24\ h post-exposure (hpe), whereas carbohydrate and glycoconjugate groups varied mainly at 24\ hpe. Our results revealed early alterations in the metabolic patterns of the host plant when interacting with the biotrophic pathogen. In addition, the FT-IR technique can be successfully applied to discriminate infected cork oak plants from mock-inoculated plants, although these differences were dynamic with time. To a lesser extent, the metabolic patterns of P.\ cinnamomi were also altered when exposed to cork oak root exudates.

}, doi = {10.1111/efp.2016.46.issue-210.1111/efp.12229}, url = {http://doi.wiley.com/10.1111/efp.2016.46.issue-2http://doi.wiley.com/10.1111/efp.12229http://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111\%2Fefp.12229}, author = {Hardoim, P. R. and Guerra, R. and Rosa da Costa, A. M. and Serrano, M. S. and Sanchez, M. E. and Coelho, A. C.}, editor = {Stenlid, J.} } @article {4557, title = {Sporulation potential, symptom expression and detection of Phytophthora ramorum on larch needles and other foliar hosts}, journal = {Plant Pathology}, volume = {65}, year = {2016}, month = {Jan-12-2016}, pages = {1441 - 1451}, abstract = {

Phytophthora ramorum has caused extensive dieback and mortality of commercially grown Japanese larch (Larix kaempferi) in many parts of the UK, as infected foliage generates spores that then cause bark lesions and girdling cankers on trees. Following inoculation, individual needles of Japanese, European (L.\ decidua) and hybrid (L.\ {\texttimes}\ eurolepis) larch infected with P.\ ramorum can produce thousands of sporangia. Mean numbers of sporangia ranged from 806 to 1778 per cm2 (hybrid larch and Japanese larch, respectively), surpassing mean sporulation levels on foliar hosts previously associated with P.\ ramorum outbreaks in Britain, namely Rhododendron ponticum, Castanea sativa and Vaccinium myrtillus. Sporulation on larch even exceeded that of California bay laurel (Umbellularia californica), which drives the sudden oak death epidemic in California. Inoculation of foliage selected at different times of year revealed that foliage age significantly affected sporulation levels, but this varied with host species. However, symptom development and sporulation were often not correlated. Symptoms on larch were frequently insignificant or even absent at certain times of year, with sometimes the only evidence of infection being the emergence of sporangia from needles, without any sign of discolouration or necrosis. Plating infected but symptomless needles onto Phytophthora selective medium also often failed to yield the pathogen. Symptomless infection of larch needles apparently occurs, but is only detectable with microscopy. More generally, it is suggested that diagnosis of Phytophthora infection in conifers is often underestimated due to isolation difficulties and delayed symptom expression.

}, doi = {10.1111/ppa.2016.65.issue-910.1111/ppa.12538}, url = {https://doi.org/10.1111/ppa.12538 }, author = {Harris, A. R. and Webber, J. F.} } @article {4708, title = {Fitness characteristics of the European lineages of Phytophthora ramorum}, journal = {Plant Pathology}, volume = {70}, year = {2021}, month = {Oct-12-2020}, pages = {275 - 286}, abstract = {

As an introduced pathogen, Phytophthora ramorum exists as four near-clonal evolutionary lineages, of which only EU1 and EU2 are established in the UK. EU1 has become widespread since the first findings in 2002 whereas EU2, detected in 2011, has a more limited distribution. Both lineages are epidemic in plantation-grown larch, sporulating asexually on needles, but also causing heavy dieback and mortality. To understand whether EU1 and EU2 pose different threats to forest health, we compared their growth characteristics on agar, pathogenicity on several hosts, and sporulation on Japanese larch needles. When pathogenicity was evaluated by measuring colonization at 20\ {\textdegree}C in mature bark (phloem) of Japanese and European larch (Larix kaempferi and L. decidua), English oak (Quercus robur), and beech (Fagus sylvatica), Japanese larch was the most susceptible and oak the least susceptible. On average, EU2 isolates produced significantly larger lesions than EU1 isolates in Japanese larch and oak although not in the other hosts. With tests using young saplings of Japanese and European larch, damaging bark lesions formed at both 10\ {\textdegree}C and 20\ {\textdegree}C, but EU2 was significantly more pathogenic at 20\ {\textdegree}C on both hosts compared with EU1. In contrast, both lineages caused similar amounts of necrosis on inoculated leaves of rhododendron (Rhododendron ponticum). Moreover, EU2 isolates usually sporulated less abundantly on larch needles compared with EU1 isolates, suggesting a trade-off in pathogenicity and sporulation between lineages. As EU2 tends to have smaller sporangia than EU1, this could also reduce the inoculum potential of EU2.

}, issn = {0032-0862}, doi = {10.1111/ppa.v70.210.1111/ppa.13292}, url = {https://bsppjournals.onlinelibrary.wiley.com/doi/abs/10.1111/ppa.13292?af=R}, author = {Harris, Anna R. and Brasier, Clive M. and Scanu, Bruno and Webber, Joan F.} } @article {4689, title = {Insights into the potential host range of Phytophthora foliorum}, journal = {Forest Pathology}, volume = {49}, year = {2019}, month = {Sep-18-2019}, pages = {e12556}, abstract = {

During a survey for Phytophthora ramorum undertaken in north-west Scotland in early 2016, Phytophthora foliorum was found infecting foliage of the invasive shrub Rhododendron ponticum. Prior to this, P.\ foliorum had only been reported from foliage of hybrid azaleas in nurseries in California and Tennessee and from azalea plants in an ornamental nursery in Spain. No other hosts were known, and much of the behaviour of P.\ foliorum remained enigmatic. The species is classified in Phytophthora Clade 8c, with closest relatives, P.\ ramorum and Phytophthora lateralis, both of which are highly damaging tree pathogens. To explore the threat that P.\ foliorum might pose to trees, its growth{\textendash}temperature responses on agar media and ability to cause lesions in the living bark of various hosts were contrasted with the behaviours of P.\ ramorum and P.\ lateralis. Phytophthora foliorum proved faster growing and more tolerant of temperature extremes than the other Phytophthora species. Comparisons of bark colonization initially focussed on R.\ ponticum and larch species Larix decidua and Larix kaempferi as all three are significant hosts of P.\ ramorum in the UK. Further experiments included another P.\ ramorum host, Fagus sylvatica (European beech), and the main host of P.\ lateralis, Chamaecyparis lawsoniana (Lawson cypress). Findings suggested that as well as being a significant pathogen of R.\ ponticum, damage caused by P.\ foliorum to both species of larch and beech was very similar to that of the EU1 lineage of P.\ ramorum, although growth in host tissue was also influenced by season.

}, doi = {10.1111/efp.v49.610.1111/efp.12556}, url = {https://onlinelibrary.wiley.com/doi/10.1111/efp.12556}, author = {Harris, Anna R. and Webber, Joan F.} } @article {4176, title = {Der Buchenkeimlingspilz, Phytophthora (Peronospora fagi M). (The beech seedling fungus Phytophthora (Peronospora fagi M))}, journal = {Untersuchungen aus dem Forstbotanischen Institut zu M{\"u}nchen}, volume = {1}, year = {1880}, pages = {33-57}, author = {Hartig, R.} } @article {4175, title = {Die Buchencotyledonen-Krankheit (The cotyledon disease of beech)}, journal = {Zeitschrift f{\"u}r Forst- und Jagdwissenschaft}, volume = {8}, year = {1876}, pages = {117-123}, author = {Hartig, R.} } @article {4178, title = {Beschadigung der Nadelhozsaatbeete durch Phytophthora omnivora (Fagi). (Damage in conifer seed beds by Phytophthora omnivora [Fagi]}, journal = {Forstwissenschaftliches Centralblatt}, volume = {27}, year = {1883}, pages = {593-596}, author = {Hartig, R.} } @inbook {4177, title = {Phytophthora omnivora (Phytophthora fagi und Peronospora sempervivi)}, booktitle = {Lehrbuch der Baumkrankheiten}, year = {1882}, pages = {42-46}, publisher = {Verlag von Julius Springer}, organization = {Verlag von Julius Springer}, address = {Berlin}, author = {Hartig, R.} } @article {412, title = {Austrocedrus chilensis: contribution to the study of its mortality in Argentina (Austrocedrus chilensis: contribuci{\'o}n al estudio de su mortalidad en Argentina)}, journal = {Bosque (Valdivia)}, volume = {10}, year = {1989}, pages = {29-36}, url = {http://mingaonline.uach.cl/scielo.php?pid=S0717-92001989000100004\&script=sci_arttext}, author = {Havrylenko, M and Rosso, P. H. and Fontela, SB} } @article {962, title = {Detection and quantification of Phytophthora ramorum from California forests using a real-time polymerase chain reaction assay-0}, journal = {Phytopathology}, volume = {94}, year = {2004}, pages = {1075-1083}, abstract = {

The timely and accurate detection of pathogens is a critical aid in the study of the epidemiology and biology of plant diseases. In the case of regulated organisms, the availability of a sensitive and reliable assay is essential when trying to achieve early detection of the pathogen. We developed and tested a real-time, nested polymerase chain reaction (PCR) assay for the detection of Phytophthora ramorum, causal agent of sudden oak death. This technique then was implemented as part of a widespread environmental screen throughout California. The method here described is sensitive, detecting less than 12 fg of pathogen DNA, and is specific for P. ramorum when tested across 21 Phytophthora spp. Hundreds of symptomatic samples from 33 sites in 14 California counties were assayed, resulting in the discovery of 10 new host species and 23 infested areas, including 4 new counties. With the exception of a single host, PCR-based discovery of new hosts and infested areas always was confirmed by traditional pathogen isolations and inoculation studies. Nonetheless, molecular diagnostics were key in early pathogen detection, and steered the direction of further research on this newly discovered and generalist Phytophthora species.

}, doi = {DOI: 10.1094/PHYTO.2004.94.10.1075}, url = {http://apsjournals.apsnet.org/doi/abs/10.1094/PHYTO.2004.94.10.1075}, author = {Katherine J. Hayden and David Rizzo and Justin Tse and Garbelotto, Matteo} } @article {Hayden20111781, title = {Will all the trees fall? Variable resistance to an introduced forest disease in a highly susceptible host}, journal = {Forest Ecology and Management}, volume = {261}, number = {11}, year = {2011}, pages = {1781 - 1791}, abstract = {

Although tanoak (Notholithocarpus densiflorus syn. Lithocarpus densiflorus) is the species most affected by the introduced pathogen Phytophthora ramorum, with demonstrable risk of extirpation, little is known about the origin, range or structuring of the tree{\textquoteright}s susceptibility. We examined variation in resistance to P. ramorum using a wound inoculation assay of detached leaves from trees at five geographically separated sites, and a non-wound inoculation assay on twigs from trees at two sites. The structure of variation in resistance was compared to the structure at nine nuclear microsatellite markers. Resistance varied quantitatively, with 23\% and 12\% of the variation among individuals and populations, respectively. There was a significant correlation between resistance in detached leaves and lesion size in non-wounding twig inoculations. Among-population genetic diversity at nine microsatellite loci was weakly structured but significantly non-zero, with 9.5\% of variation among populations. Within-population neutral genetic diversity was a poor predictor of resistance, and estimates of phenotypic distances for resistance were no greater than neutral genetic distances. The limited phenotypic and genetic structure we found indicates that tanoaks at all study sites are susceptible, and there is no evidence of prior selection for disease resistance. We conclude that tanoak populations across the species{\textquoteright} range are at risk, but local disease dynamics will depend on both host genetics and environmental conditions.

}, keywords = {Sudden oak death}, issn = {0378-1127}, doi = {DOI: 10.1016/j.foreco.2011.01.042}, url = {http://www.sciencedirect.com/science/article/B6T6X-52F7TF6-1/2/55216e9ccfc0fafe0035e3d3f20ff81b}, author = {Katherine J. Hayden and Alejandro Nettel and Richard S. Dodd and Garbelotto, Matteo} } @article {4245, title = {First Report of Phytophthora hedraiandra Causing Rhododendron Dieback and Root Rot of Common Beech in the Czech Republic}, journal = {Plant Disease}, volume = {98}, year = {2014}, month = {10/2014}, pages = {1434 - 1434}, abstract = {

From 2010 to 2012, Phytophthora isolates were obtained from brownish diffusion leaf lesions usually up to 2 to 3 cm in diameter of Rhododendron caucasicum {\textquoteleft}Cheer,{\textquoteright} from withered twigs of Rhododendron sp. with blackish elongated lesions up to ~5 cm in length, and from rotten feeder roots of 2-year-old, chlorotic, wilting seedlings of Fagus sylvatica collected from ornamental and forest nurseries in three areas (central and eastern Bohemia and northern Moravia) in the Czech Republic. Isolates formed chrysanthemum-like to slightly stellate, appressed colonies with sparse aerial mycelium on V8 agar (V8A) plates at 20{\textdegree}C after 5 days, whereas on carrot agar (CA) plates the pattern was vague with no aerial mycelium. The cardinal growth temperatures were: min. 3{\textdegree}C, optimum 23 to 27{\textdegree}C, and max. 31{\textdegree}C. Radial growth was 5.7 to 6.6 mm/day at 20{\textdegree}C on V8A. The isolates were homothallic and produced colorless, smooth-walled, spherical oogonia with an average diameter 29.9 to 33.8 μm on CA. Oospores were aplerotic (avg. 26.4 to 29.3 μm), oospore wall was hyaline and averaged 1.3 to 1.7 μm thick, oospore wall index was 0.26 to 0.32. Paragynous or occasionally amphigynous antheridia averaged 13.4 to 15.0 {\texttimes} 10.9 to 12.5 μm (height {\texttimes} width). Sporangia were caducous, papillate, globose, spherical to ovoid, with short pedicels (avg. 2.1 to 2.6 μm) and averaged 30.9 to 41.5 {\texttimes} 25.5 to 30.6 μm, L:B ratio was 1.2 to 1.4. Chlamydospores were not observed. Morphological characters resembled those described for P. hedraiandra (1). The isolates were deposited in the collection of phytopathogenic oomycetes of RILOG Pruhonice and given accession nos. 450.11, 531.11, and 578.12. The isolates were sequenced for nuclear rDNA ITS region and partial Cox I gene. Obtained sequences were compared with sequences present in GenBank database using BLAST. The ITS sequences of all isolates (GenBank Accession Nos. KJ567081, 82, and 83) of overall length of 792 bp were identical to that of P. hedraiandra AY707987 (1). The Cox I sequences of overall length of 880 bp (KJ567084, 85, and 86) showed 99\% homology (1 bp substitution) with AY769115 (1) and 100\% identity with other Cox I sequences of P. hedraiandra, i.e., JN376067 (4) and EF174432 (3). Koch{\textquoteright}s postulates were confirmed by wound-inoculating of 3-year-old rhododendron and common beech plants (10 host plants per corresponding isolate). Rhododendron leaves were gently abraded near the midrib, whereas 5-mm-diameter bark plugs were removed from the beech collars. The inoculum (5-mm-diameter V8A plug with actively growing mycelium) was placed over wounds and sealed with Parafilm. Control plants were treated in the same manner with sterile agar plugs. Plants were maintained in a greenhouse at 22{\textdegree}C. All inoculated plants showed disease symptoms after 10 days of incubation; the lesions were up to 2 cm in rhododendron leaves and ~1 cm in beech collars. Control plants remained healthy. The pathogen was re-isolated from all infected plants. To our knowledge, this is the first report of P. hedraiandra in the Czech Republic. Besides it, the pathogen was found in southern and western Europe (Italy, Slovenia, Spain, the Netherlands) and in the United States (2)

}, issn = {0191-2917}, doi = {10.1094/PDIS-04-14-0339-PDN}, url = {http://apsjournals.apsnet.org/doi/abs/10.1094/PDIS-04-14-0339-PDN}, author = {Hejna, M. and Cerny, K. and Havrdova, L. and Mrazkova, M.} } @article {4604, title = {Morphological and genetic analyses of the invasive forest pathogen Phytophthora austrocedri reveal that two clonal lineages colonized Britain and Argentina from a common ancestral population}, journal = {Phytopathology}, volume = {107}, year = {2017}, month = {Jan-12-2017}, pages = {1532 - 1540}, abstract = {

Phytophthora austrocedri is causing widespread mortality of Austrocedrus chilensis in Argentina and Juniperus communis in Britain. The pathogen has also been isolated from J. horizontalis in Germany. Isolates from Britain, Argentina, and Germany are homothallic, with no clear differences in the dimensions of sporangia, oogonia, or oospores. Argentinian and German isolates grew faster than British isolates across a range of media and had a higher temperature tolerance, although most isolates, regardless of origin, grew best at 15{\textdegree}C and all isolates were killed at 25{\textdegree}C. Argentinian and British isolates caused lesions when inoculated onto both A. chilensis and J. communis; however, the Argentinian isolate caused longer lesions on A. chilensis than on J. communis and vice versa for the British isolate. Genetic analyses of nuclear and mitochondrial loci showed that all British isolates are identical. Argentinian isolates and the German isolate are also identical but differ from the British isolates. Single-nucleotide polymorphisms are shared between the British and Argentinian isolates. We concluded that British isolates and Argentinian isolates conform to two distinct clonal lineages of P. austrocedri founded from the same as-yet-unidentified source population. These lineages should be recognized and treated as separate risks by international plant health legislation.

}, issn = {0031-949X}, doi = {10.1094/PHYTO-03-17-0126-R}, url = {https://apsjournals.apsnet.org/doi/10.1094/PHYTO-03-17-0126-Rhttps://apsjournals.apsnet.org/doi/pdf/10.1094/PHYTO-03-17-0126-R}, author = {Henricot, B{\'e}atrice and P{\'e}rez-Sierra, Ana and Armstrong, April C. and Sharp, Paul M. and Green, Sarah} } @article {4044, title = {Studies on the chemical control of Phytophthora palmivora (Butl.) Butl. on Theobroma cacao L. in Nigeria.}, journal = {Annals of Applied Biology}, volume = {52}, year = {1963}, month = {12/1963}, pages = {465 - 480}, abstract = {

In laboratory trials, phenyl mercury nitrate at 0{\textperiodcentered}02 p.p.m. and fentin acetate at 0{\textperiodcentered}2 p.p.m. severely retarded growth of four isolates of Phytophthora palmivora on cassava agar. These two chemicals, with captan, maneb and a dithiocarbamate-copper chelate, were also highly toxic to encysted zoospores of a {\textquoteleft}rubber{\textquoteright} group isolate of P. palmivora.

Deposits of captan on pods were readily removed by artificial rain, but some improvement in tenacity was obtained by the addition of a sticker. In other laboratory trials, the deposit from low-volume sprays of cuprous oxide dried more quickly on pods than that from high-volume sprays but showed no advantage in subsequent resistance to weathering.

In a field trial in 1961, seven fungicide treatments were applied three-weekly and compared with an unsprayed control. The lowest percentage black-pod infection followed treatment with fentin acetate: Bordeaux mixture and carbide Bordeaux both gave good control. The captan treatments were completely ineffective. More black pods were harvested from close-spaced trees than from those wide-spaced.

Weekly applications of 0{\textperiodcentered}15\% fentin acetate to seedlings induced no significant damage.

In a field trial made in 1962 very heavy rainfall provided a severe test of the fungicides, the most effective being Bordeaux mixture and carbide Bordeaux mixture applied three-weekly, carbide Bordeaux mixture applied four-weekly and fentin acetate applied two-weekly. Captan with added sticker was again no better than the control. There was no marked effect of spacing.

Comparisons of Bordeaux and carbide Bordeaux mixtures made at two other sites in 1962 showed no difference in disease control. It is suggested that carbide Bordeaux mixture could be replaced by the cheaper preparation made with lime.

}, issn = {0003-4746}, doi = {10.1111/aab.1963.52.issue-310.1111/j.1744-7348.1963.tb03770.x}, url = {http://onlinelibrary.wiley.com/doi/10.1111/j.1744-7348.1963.tb03770.x/abstract;jsessionid=FA42764CD24DC2258C2776AF065DAB4F.d01t01}, author = {Hislop, E. C.} } @article {698, title = {Synoptic keys to the species of Phytophthora}, journal = {Mycologia}, volume = {73}, year = {1981}, pages = {705-714}, publisher = {Mycological Society of America}, abstract = {

Three synoptic keys to the species of Phytophthora are presented to facilitate identification of, respectively, the plant pathogenic species in culture, the plant pathogenic species known only on hosts, and the aquatic species.

}, url = {http://www.jstor.org/stable/3759497}, author = {Ho, HH} } @article {ho2002phytophthora, title = {Phytophthora cinnamomi var. robiniae var. nova on black locust in jiangsu province of China}, journal = {Mycotaxon}, volume = {82}, year = {2002}, pages = {391{\textendash}396}, publisher = {Mycotaxon}, issn = {0093-4666}, author = {Ho, HH} } @article {4045, title = {Efficacy of Neutralised Phosphonic Acid (Phosphorous Acid) Against Phytophthora Palmivora Pod Rot and Canker of Cocoa.}, journal = {Australasian Plant Pathology}, volume = {19}, year = {1990}, month = {1990}, pages = {130}, abstract = {

In comparative trials under a wide range of environmental conditions and management inputs, injection of cocoa trees with partially pH-neutralised phosphonic acid (H3PO3) gave similar, or better, control of pod rot caused by Phytophthora palmivora to that obtained with metalaxyl/cuprous oxide pod sprays. lnjection reduced canker incidence by up to 90\% at some sites. Foliar sprays of phosphonic acid had little effect on yield or pod rot incidence at rates up to 24 g a.i./tree/application. Studies to determine the optimum dose and frequency of injection have shown a clear benefit of treatment, with both increased yields and reduced pod rot incidence, but no yield advantage was obtained through high dose rates. Alginate gel paints and direct root uptake were evaluated as alternative application methods, but were less effective than injection. H3PO3 was ineffective against vascular-streak dieback disease of cocoa, caused by Oncobasidium theobromae.

}, issn = {0815-3191}, doi = {10.1071/APP9900130}, url = {http://link.springer.com/article/10.1071\%2FAPP9900130}, author = {Holderness, M} } @article {ChuanxueHong03012011, title = {Phytophthora pini Leonian resurrected to distinct species status}, journal = {Mycologia}, volume = {103}, number = {2}, year = {2011}, pages = {351-360}, abstract = {

Phytophthora pini was named by Leonian in 1925, but this species was largely ignored until 1956 and then merged with P. citricola by Waterhouse in 1963. This study compared the ex-type and ex-authentic cultures of these two species with isolates of P. plurivora and the P. citricola subgroups Cil I and III reported previously. Examination of these isolates revealed that the ex-type culture of P. pini is identical to P. citricola I. Phytophthora pini Leonian therefore is resurrected to distinct species status and redescribed here with a Latin description, replacing P. citricola I. Molecular, physiological and morphological descriptions of this species are presented. The molecular description includes DNA sequences of five nuclear and mitochondrial regions as well as PCR-SSCP fingerprints. The relationship among the above species and other species recently segregated from the P. citricola complex also is discussed.

}, doi = {10.3852/10-058}, url = {http://www.mycologia.org/cgi/content/abstract/103/2/351}, author = {Hong, Chuanxue and Gallegly, Mannon E. and Richardson, Patricia A. and Kong, Ping} } @article {4081, title = {Crown rot of Abies balsamea var. phanerolepis caused by Phytophthora cactorum in Virginia}, journal = {Plant Disease}, volume = {89}, year = {2005}, month = {04/2005}, pages = {433 - 433}, abstract = {

In early July 2004, a severe crown rot of Canaan fir (Abies balsamea var. phanerolepis Fern.) was reported to the Virginia Cooperative Extension, Frederick County Office, and subsequently to the Virginia Tech Disease Clinic in Virginia Beach. One thousand five-year-old Canaan fir transplants (approximately 11 mm in caliper and 31 cm high) had been purchased from a tree nursery in Oregon and planted in the field in Frederick County, VA, in April of 2004. The field site had not been cultivated for 4 years after an apple orchard had been removed in 2000. By mid-May, needle browning had become serious, affecting the lower crown first. By August, transplants had suffered 40\% mortality. Basal stems of affected plants were obviously discolored. Root and basal stem samples from several infected plants were then cultured on PARP-V8 agar on three different dates. Phytophthora sp. isolates were recovered from all stem samples but none from the roots. These isolates produced a large number of papillate sporangia that were caducous with short pedicels. Abundant oogonia with paragynous antheridia formed oospores directly on isolation plates within 7 days. The isolates were keyed as P. cactorum (2). This identification was confirmed using a single-strand-conformation polymorphism analysis of ribosomal DNA internal transcribed spacer (ITS)-1 (4). It appears that the source of inoculum was P. cactorum associated with the previous apple crop, since Canaan fir from the same transplant lot planted in a nearby field without a history of apples remained healthy. P. cactorum has been reported to cause root rot of noble fir (A. procera Rhedo), Pacific silver fir (A. amabilis (Dougl.) Forbes), and Shasta red fir (A. magnifica var. shastensis Lemm.) in the Pacific Northwest (3). It has also caused crown rot of Fraser fir (A. fraseri (Pursh) Poir.), noble fir, white fir (A. concolor (Gord. \& Glend.) Lindl.), and balsam fir (A. balsamea (L.) Mill.) in Michigan (1). To our knowledge, this is the first report of P. cactorum attacking Canaan fir. Canaan fir currently is a recommended Christmas tree species for areas where Fraser fir does not do well due to root rot caused by Phytophthora cinnamomi. This study suggests that such a recommendation must be used with caution. Growing Canaan fir trees in P. cactorum-infested soil could result in devastating crop losses as reported in this note.

}, issn = {0191-2917}, doi = {10.1094/PD-89-0433B}, url = { http://dx.doi.org/10.1094/PD-89-0433B }, author = {Hong, C. X. and Marston, C. D.} } @article {4229, title = {Decline in vitality of propagules of Phytophthora pluvialis and Phytophthora kernoviae and their inability to contaminate or colonise bark and sapwood in Pinus radiata export log simulation studies}, journal = {New Zealand Journal of Forestry Science}, volume = {44}, year = {2014}, month = {Jan-12-2014}, pages = {13 pp}, abstract = {

Background: Phytophthora pluvialis Reeser, W.L. Sutton \& E.M. Hansen is the cause of a newly described disease, red needle cast, in certain stands of Pinus radiata D. Don in New Zealand that experience periodic foliage browning, while Phytophthora kernoviae Brasier, Beales \& Kirk is also infrequently isolated from symptomatic needles.

Methods: Studies were undertaken to test the possibility that these species may be transported on pine logs either as superficial contaminants or as colonists of bark or wood.

Results: Pine-needle baiting found no evidence of Phytophthora species in bark samples or aqueous bark washes from stems of 603 symptomatic trees in 17 affected stands implying that survival after natural deposition of sporangia or zoospores is low or absent. The persistence of zoospores or oospores was evaluated at intervals after applying them at artificially high surface densities to the bark on log segments and incubating at five temperatures between 15{\textdegree}C and 35{\textdegree}C in the laboratory. The ability to re-isolate Phytophthora kernoviae decreased with time and increasing temperature, but this species was s till obtained at low frequencies after 4 weeks at 15{\textdegree}C and 20{\textdegree}C following treatment with oospores of Phytophthora kernoviae. Phytophthora pluvialis could not be isolated under any conditions of time or temperature tested. Percentage vitality of oospores of both species as determined using tetrazolium bromide vital staining also decreased with time, although some oospores of both species remained alive after 4 weeks at all temperatures tested. In a further study to test potential log colonisation, Phytophthora spp. were not isolated from bark or xylem at or near points where zoospores, oospores or mycelium of either species were applied to the bark or sapwood of pine segments and incubated for 6 weeks under ambient or humid conditions at 17{\textdegree}C.

Conclusion: The results of these studies suggest that occurrence of Phytophthora kernoviae or Phytophthora pluvialis on export logs from affected stands is negligible. In addition, although some remained alive, the substantial decline in vitality among artificially applied oospores implies that the survival of any few that may be naturally present on logs is likely to be slight. Based on the evidence from this work there appears to be little risk of transporting these Phytophthora species on New Zealand radiata pine logs.

}, doi = {10.1186/s40490-014-0007-6}, url = {http://www.nzjforestryscience.com/content/44/1/7}, author = {Hood, Ian A and Williams, Nari M and Dick, Margaret A and Arhipova, Natalija and Kimberley, Mark O and Scott, Peter M and Gardner, Judy F} } @article {4456, title = {Phosphorus acid for controlling Phytophthora {\textquoteleft}taxon Agathis{\textquoteright} in kauri: glasshouse trials. }, journal = {New Zealand Plant Protection}, volume = {66}, year = {2013}, pages = {242-248}, abstract = {

Phytophthora taxon Agathis (PTA) is a serious problem in Auckland and Northland kauri forests. Phosphorous acid (phosphite) is a potential treatment for infected or threatened trees. In vitro tests on phosphite-amended agar showed that PTA was more sensitive to phosphite than other Phytophthora species commonly controlled by this chemical. Before progressing to forest trials, phosphite efficacy was tested on PTA-inoculated kauri seedlings in the glasshouse. Two-year-old kauri seedlings were inoculated with PTA applied directly to trunk wounds or by soil application. Phosphite was applied as a foliar spray, as a trunk injection or as a soil drench either 5 days before or 5 days after inoculation. All untreated control trees died, whether trunk- or soil-inoculated. With phosphite injection, survival was 100\% following PTA soil inoculation and 67\% following trunk inoculation. Foliar spray and soil drench-applied phosphite treatments were less effective than trunk injection, although some trees survived.

}, issn = {1175-9003 (print), 1179-352X (online)},}, url = {http://www.nzpps.org/nzpp_abstract.php?paper=662420}, author = {Horner, I.J. and Hough, E.G.} } @article {3979, title = {Identification of Phytophthora species baited and isolated from forest soil and streams in northwestern Yunnan province, China}, journal = {Forest Pathology}, year = {2013}, month = {01/2013}, pages = {n/a - n/a}, abstract = {

Phytophthora species were surveyed by collecting soil samples and placing bait leaves in selected streams during June{\textendash}October in the years 2005, 2006 and 2010 at three sites in oak forests in Diqing Tibetan Autonomous Prefecture of NW Yunnan province, China. Seventy-three isolates of Phytophthora spp. were recovered from 135 baited leaf samples and 81 soil samples. Eight Phytophthora species were identified by observation of morphological features and ITS1-5.8S-ITS2 rDNA sequence analysis. The eight taxa included two well-known species P.\ gonapodyides and P.\ cryptogea, two recently described species P.\ gregata and P.\ plurivora, two named but as yet undescribed taxa, P.\ taxon PgChlamydo and P.\ taxon Salixsoil, and two previously unrecognized species, Phytophthora sp.1 and P. sp.2. The most numerous species, P.\ taxon PgChlamydo, and the second most abundant species, P.\ taxon Salixsoil, were recovered at all three sites. Phytophthora cryptogea was detected only once at site Nixi. Phytophthora gregata and P. sp.2 were isolated from a stream only at site Bitahai, while the other three species were each found at two sites. Phylogenetic analysis revealed that the isolates belonged to three ITS clades, one species including six isolates in clade 2, six species including 66 isolates in clade 6 and one species in clade 8. There was a relatively rich species and genetic diversity of Phytophthora detected in the investigated regions where the forest biotic and abiotic factors affecting the growth and evolution of Phytophthora populations were diverse.

}, doi = {10.1111/efp.12015}, author = {Huai, W.-x. and Tian, G. and Hansen, E.M. and Zhao, W.-x. and Goheen, E. M. and N. J. Gr{\"u}nwald and Cheng, C.}, editor = {Belbahri, L.} } @article {1264, title = {First report of Phytophthora cambivora causing leaf and stem blight and root rot on Taiwan cherry (Prunus campanulata) in Taiwan}, journal = {Plant Disease}, volume = {96}, year = {2012}, pages = {1065-1065}, abstract = {

Taiwan cherry or Formosan cherry (Prunus campanulata Maxim.) is a beautiful ornamental tree that is native to Taiwan. In spring 2005, a severe disease was observed on 1- to 3-year-old seedlings of Taiwan cherry in a garden in Tungshih, Taichung, Taiwan. Infected plants showed symptoms of greenish water-soaked spots on leaves that became dark brown, 2 to 3 cm in diameter. Infected leaves withered and fell to the ground in 3 to 5 days and young shoots showed symptoms of withering and drooping. Infected roots showed symptoms of necrosis. Severely infected plants eventually died. A Phytophthora sp. was isolated consistently from diseased samples of Taiwan cherry and associated soil. Six isolates of Phytophthora, of the A1 mating type (1), were isolated from single zoospores. Two of these isolates, Tari 25141 (deposited as BCRC34932 in Bioresource Collection and Research Center, Shinchu, Taiwan) and Tari 25144 (BCRC34933), were used for pathogenicity tests on 1-year-old seedlings of Taiwan cherry to fulfill Koch{\textquoteright}s postulates. Inoculation was done by placing a cotton swab containing zoospore suspension on leaves or stem, or by soaking seedlings in the zoospore suspension. Inoculated seedlings were kept in a greenhouse at 20 to 25{\textdegree}C for 30 days and examined for appearance of symptoms. Results showed that both isolates were pathogenic on seedlings of Taiwan cherry, causing symptoms similar to those observed on naturally infected seedlings. The temperature range for growth of the six isolates of Phytophthora was 8 to 32{\textdegree}C with optimum temperature at 24{\textdegree}C. The linear growth rate was 72 mm per day on V8A culture (5\% V8 vegetable juice, 0.02\% CaCO3, and 2\% Bacto agar) at 24{\textdegree}C. The colonies on potato dextrose agar produced sparse aerial mycelia with conspicuous radiate patterns. Sporangia were sparse on V8A agar blocks, but abundant when the agar blocks were placed in water under continuous white fluorescent light (average 2,000 lux) for 2 days. Sporangiophores branched sympodially. Sporangia were pear shaped, nonpapillate and nondeciduous, 50 to 75 (62) {\texttimes} 30 to 48 (40) μm, with a length/width ratio of 1.2 to 2.2 (1.6). New internal nested proliferate sporangia were formed inside the empty sac of old matured sporangia after releasing zoospores. No chlamydospores were formed on V8A. Hyphal swellings with distinctive irregular catenulation were produced on V8A and in water. The pathogen was stimulated to form its own oospores by the A2 tester using the method described by Ko (1). Oogonia were 28 to 50 (40) μm in diameter with smooth or irregularly protuberant walls. Oospores were mostly aplerotic and 18 to 42 (31) μm in diameter. Antheridia were amphigynous, mostly two-celled, and 10 to 42 (29) {\texttimes} 12 to 24 (19) μm. The sequence of the internal transcribed spacers (ITS) region of nuclear ribosomal DNA of isolate Tari 25141 (GenBank Accession No. GU111589) was 831 bp and had 99\% sequence identity with a number of Phytophthora cambivora isolates such as GenBank Accession Nos. HM004220 (2), AY787030, and EF486692. Based on the morphological characteristics of sporangia and sexual structures and the molecular analysis of ITS sequences, the pathogen from Taiwan cherry was identified as P. cambivora (Petri) Buis. To our knowledge, this is the first report of P. cambivora on native Taiwan cherry in Taiwan and, so far, no other natural hosts have been reported.

}, doi = {10.1094/PDIS-01-12-0025-PDN}, url = {http://dx.doi.org/10.1094/PDIS-01-12-0025-PDN}, author = {J.H. Huang and Ann, PJ and Y.H. Chiu and J.N. Tsai} } @article {EFP:EFP715, title = {Phytophthora ramorum is a generalist plant pathogen with differences in virulence between isolates from infectious and dead-end hosts}, journal = {Forest Pathology}, volume = {42}, number = {1}, year = {2012}, pages = {8{\textendash}13}, publisher = {Blackwell Publishing Ltd}, abstract = {

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 leaves of Umbellularia californica (bay laurel or bay) and stems of Quercus agrifolia (coast live oak). In spite of extreme genetic similarity among the isolates employed, and even within the same genotype, significant differences in lesion size were measured, suggesting virulence in this pathogen is also controlled by epigenetic factors. A strong positive correlation between lesion size on bay laurel and coast live oak provides experimental evidence P.\ ramorum is a generalist pathogen that lacks host specificity. Isolates from non-transmissive oaks were significantly less pathogenic both on oaks and bays than isolates from infectious hosts. These results are essential to further our understanding of the epidemiology and evolutionary potential of this pathogen. A quantitative differential in virulence of isolates from hosts with different epidemiological roles has been described for many animal diseases, but is a novel report for a plant disease.

}, issn = {1439-0329}, doi = {10.1111/j.1439-0329.2011.00715.x}, url = {http://dx.doi.org/10.1111/j.1439-0329.2011.00715.x}, author = {H{\"u}berli, D. and Garbelotto, M.} } @article {1365, title = {Development of a real-time PCR assay for detection of Phytophthora kernoviae and comparison of this method with a conventional culturing technique}, journal = {European Journal of Plant Pathology}, volume = {131}, year = {2011}, pages = {695-703}, publisher = {Springer Netherlands}, abstract = {

Phytophthora kernoviae is a recently described pathogen causing leaf blight, aerial dieback and bleeding cankers on trees and shrubs in parts of Great Britain and Ireland and recently reported in New Zealand. This paper describes the development of a TaqMan real-time PCR assay based on internal transcribed spacer (ITS) sequence to aid diagnosis of this pathogen in culture and in plant material. The assay showed no cross reaction with 29 other Phytophthora species, including the closely related species P. boehmeriae, and detected at least 1.2\ pg of P. kernoviae DNA per reaction. A rapid and simple method can be used to extract DNA prior to testing by real-time PCR, and a plant internal control assay can be used to aid interpretation of negative results. A comparison of real-time PCR and plating for 526 plant samples collected in the UK indicated that this assay is suitable for use in routine screening for P. kernoviae.

}, keywords = {Diagnostic sensitivity, Diagnostic specificity, plant health, Rhododendron}, issn = {0929-1873}, doi = {10.1007/s10658-011-9843-x}, url = {http://dx.doi.org/10.1007/s10658-011-9843-x}, author = {Hughes, KelvinJ.D. and Tomlinson, JennyA. and Giltrap, PatriciaM. and Barton, Victoria and Hobden, Ellie and Boonham, Neil and Lane, CharlesR.} }