00341nas a2200097 4500008004100000245004100041210004000082100001500122700001300137856009300150 2008 eng d00aSudden oak death and ramorum blight.0 aSudden oak death and ramorum blight1 aParke, J L1 aLucas, S uhttp://www.apsnet.org/edcenter/intropp/lessons/fungi/Oomycetes/Pages/SuddenOakDeath.aspx00719nas a2200205 4500008004100000245006500041210006000106260011100166300000800277490003200285100001500317700001600332700001300348700001500361700001900376700001700395700001900412700001800431856006400449 2010 eng d00aThe Phytophthora online course: Training for nursery growers0 aPhytophthora online course Training for nursery growers aSanta Cruz, CaliforniabU.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station a3550 vGen. Tech. Rep. PSW-GTR-2291 aParke, J L1 aPscheidt, J1 aRegan, R1 aHedberg, J1 aGrünwald, N J1 aFrankel, S J1 aKliejunas, J T1 aPalmieri, K M uhttp://www.fs.fed.us/psw/publications/documents/psw_gtr229/00558nas a2200169 4500008004100000245010000041210006900141300001400210490000700224100001500231700001000246700001500256700001600271700001500287700001900302856006700321 2007 eng d00aPhytophthora ramorum colonizes tanoak xylem and is associated with reduced stem water transport0 aPhytophthora ramorum colonizes tanoak xylem and is associated wi a1558-15670 v971 aParke, J L1 aOh, E1 aVoelker, S1 aHansen, E M1 aBuckles, G1 aLachenbruch, B uhttp://apsjournals.apsnet.org/doi/abs/10.1094/PHYTO-97-12-155800641nas a2200193 4500008004100000245008800041210006900129260002700198300001000225490003200235100001500267700001900282700001300301700001500314700001700329700001900346700001800365856006400383 2010 eng d00aA systems approach for detecting sources of Phytophthora contamination in nurseries0 asystems approach for detecting sources of Phytophthora contamina aSanta Cruz, California a67-680 vGen. Tech. Rep. PSW-GTR-2291 aParke, J L1 aGrünwald, N J1 aLewis, C1 aFieland, V1 aFrankel, S J1 aKliejunas, J T1 aPalmieri, K M uhttp://www.fs.fed.us/psw/publications/documents/psw_gtr229/01142nas a2200145 4500008004100000022001400041245008000055210006900135260001600204300001400220490000800234520069100242100002500933856003800958 2013 eng d a2154-888900aPhytophthora castaneae, the correct name for P. katsurae nom. nov. superfl.0 aPhytophthora castaneae the correct name for P katsurae nom nov s cSep-01-2013 a327 - 3310 v1213 a

Phytophthora katsurae was proposed as a nom. nov. for P. castaneaeon the assumption that the replaced name was an illegitimate later homonym. This assumption was based on the invalid nomen nudum publication of “Phytophthora castaneae” in a host–pathogen index as a synonym of Mycelophagus castaneae, and an erroneous interpretation of Clements & Shear’s listing of the type of the genus Mycelophagus. There is no valid earlier homonym. Phytophthora castaneae is the correct legitimate name for the taxon causing trunk rot of Castanea crenata, and P. katsurae is an illegitimate superfluous name.

1 aPennycook, Shaun, R. uhttp://dx.doi.org/10.5248/121.32702423nas a2200265 4500008004100000022001400041245015900055210006900214260002900283300001600312490000700328520156000335653002501895653001601920653001401936653001401950653002401964653002101988100002102009700001802030700001902048700001602067700001902083856005502102 2011 eng d a1365-305900aGenetic diversity, sensitivity to phenylamide fungicides and aggressiveness of Phytophthora ramorum on Camellia, Rhododendron and Viburnum plants in Spain0 aGenetic diversity sensitivity to phenylamide fungicides and aggr bBlackwell Publishing Ltd a1069–10760 v603 a

Phytophthora ramorum has been detected in official plant health surveys on Rhododendron, Viburnum and Camellia in ornamental nurseries in northern Spain since 2003. A collection of 94 isolates of P. ramorum was obtained from 2003 to 2008 from plants with symptoms at different geographical locations. Isolates were identified based on morphology and sequence of the rDNA ITS region. Mating type, genetic variation, sensitivity to phenylamide fungicides and aggressiveness of these isolates were determined. All isolates belonged to the A1 mating type, ruling out the possibility of genetic recombination. Seven microsatellite markers were used to study genetic diversity; three out of the seven microsatellite markers were polymorphic within the Spanish population of P. ramorum. This study confirms that all Spanish isolates of P. ramorum belonged to the EU1 lineage. Twelve intralineage genotypes were detected, five that are unique to Spain (EU1MG38, EU1MG41, EU1MG37, EU1MG39 and EU1MG40) and seven that are also present in at least one other European country (EU1MG1, EU1MG29, EU1MG22, EU1MG13, EU1MG2, EU1MG18 and EU1MG26). Genotypes EU1MG37, EU1MG39 and EU1MG40 were isolated from Rhododendron from one region; EU1MG38 and EU1MG41 were isolated from Camellia from two different regions. Isolates of genotype EU1MG38 were resistant to metalaxyl and mefenoxam. The level of genetic diversity within the Spanish population of P. ramorum is limited and indicates a relatively recent clonal expansion.

10afungicide resistance10ahost origin10amefenoxam10ametalaxyl10amultilocus genotype10aSudden oak death1 aPérez-Sierra, A1 aÁlvarez, L A1 aVercauteren, A1 aHeungens, K1 aAbad-Campos, P uhttp://dx.doi.org/10.1111/j.1365-3059.2011.02485.x02979nas a2200205 4500008004100000022001400041245013800055210006900193260001200262300001400274490000700288520232700295100002102622700002202643700001302665700002402678700001902702700001202721856004002733 2013 eng d a1439-032900aPreviously unrecorded low-temperature Phytophthora species associated with Quercus decline in a Mediterranean forest in eastern Spain0 aPreviously unrecorded lowtemperature Phytophthora species associ c08/2013 a331–3390 v433 a

Oak decline has been a serious problem in Europe since the beginning of the twentieth century. In south-west Spain, Quercus ilex and Q. suber are the main affected species, and their decline has been associated with Phytophthora cinnamomi. During the last 10 years, a severe decline of Q. ilex and Q. faginea accompanied by a significant decrease in the production of acorns affecting natural regeneration was observed in the eastern part of the Iberian Peninsula. Therefore, the aim of this study was to investigate the possible involvement of Phytophthora spp. in the decline. A forest in the Natural Park ‘Carrascar de la Font Roja’ in Comunidad Valenciana (eastern Spain), which is dominated by Q. ilex and Q. faginea, was surveyed during 2010–2011. Symptomatic trees showed thinning and dieback of the crown, withering of leaves and death. An extensive loss of both lateral small woody roots and fine roots and callusing or open cankers on suberized roots were observed. Soil samples containing fine roots were baited using both Q. robur leaves and apple fruits. Six Phytophthora species were isolated: P. cryptogea, P. gonapodyides, P. megasperma, P. quercina, P. psychrophila and P. syringae. These are the first records of P. quercina and P. psychrophila on Q. faginea, of P. quercina in Spain and of P. psychrophila in mainland Spain. A soil infestation trial was conducted for 6 months under controlled conditions with 1-year-old seedlings of Q. ilex and Q. faginea. Phytophthora cinnamomi was included in the pathogenicity test for comparison. The results showed that Q. ilex seedlings were generally more susceptible to infection than Q. faginea with P. cinnamomi being the most aggressive pathogen to both oak species. The two most commonly isolated Phytophthora species, P. quercina and P. psychrophila, also proved their pathogenicity towards both Q. ilex and Q. faginea.

1 aPérez-Sierra, A1 aLópez-García, C1 aLeón, M1 aGarcía-Jiménez, J1 aAbad-Campos, P1 aJung, T uhttp://dx.doi.org/10.1111/efp.1203704709nas a2200169 4500008004100000245008000041210006900121260001600190300000700206490000700213520414600220100002104366700002204387700002104409700001804430856009104448 2015 eng d00aPhytophthora siskiyouensis causing stem lesions and cankers on Alnus incana0 aPhytophthora siskiyouensis causing stem lesions and cankers on A cJun-06-2017 a170 v313 a

In late summer 2013, stem cankers and sparse foliage were reported on European grey alder (Alnus incana) growing on a 500 ha site recently-planted with broadleaf and coniferous trees in south-west England. A site visit showed that approximately 10% of  more than 1000 grey alders (thought to have been imported from Europe and planted in the late 1990s) had symptoms including bleeding stem lesions similar to those caused by Phytophthora alni (Gibbs et al., 2003). In November 2013, samples were collected from stem lesions (Fig. 1), roots (internal lesions tracking-down from stem lesions) and rhizosphere soil from symptom-bearing trees. Tissue from root and stem lesion margins was plated onto Phytophthora selective medium (SMA) (amended as per Brasier et al., 2005) and incubated at 20°C for 48 hrs. Green apples were used as baits for soil samples by inserting a few grams of soil under a flap cut in the side of the apple and incubating for 4-7 days at 20°C. Isolation from developing SMA mycelial cultures and incubated apple baits onto potato dextrose agar (PDA) and carrot agar (CA) was then undertaken.

After 14 days on PDA at 20°C in the dark, colonies exhibited a distinctive stellate growth pattern (Fig. 2a). On CA they had a diffuse 'frosty' appearance (Fig. 2b). On CA, oogonia with predominantly paragynous antheridia and aplerotic oospores were abundant. Partially-caducous sporangia formed when plugs from colonies on CA were submerged in unsterile pond water held at 20°C in the dark. Sporangia (46-51 μm wide) were semi-papillate and were ovoid, reniform, elongated or irregular in shape (Fig. 3). Sporangial morphology and dimensions corresponded to Phytophthora siskiyouensis (Reeser et al., 2007) and sequences of ITS and coxII regions supported this identification (GenBank Accession Nos. KP207601 and KP207602). 

One isolate of P. siskiyouensis was obtained from each of three different symptomatic trees; one from a root lesion, one from a stem lesion and one from associated soil. Koch’s postulates were tested by inoculating two-year-old potted A. incana saplings with the three isolates. A small wound was made on the stem 10 cm above soil level. A CA plug colonised by P. siskiyouensis was inserted and the wound was sealed with Parafilm. Nine saplings were inoculated per isolate and maintained at 20°C with a 12-hr-photoperiod. Three control saplings were inoculated with sterile CA plugs. After 20 days, cankers and bleeding were visible externally on all of the trees inoculated with P. siskiyouensis (Fig. 4). The bark was peeled away to reveal phloem lesions extending approximately 2-4 cm above and below the inoculation point. No lesions developed on control trees. After re-isolation onto SMA, a Phytophthora sp. was recovered from all of the inoculated trees but not from the controls and it was identified as P. siskiyouensis by morphology (Reeser et al., 2007) and sequencing of the ITS region.

Phytophthora siskiyouensis is a recently-described species in the USA, isolated from stem lesions on myrtlewood (Umbellularia californica) and tanoak (Lithocarpus densiflorus; synonym of Nothocarpus densiflorus) and from soil and stream water, in south-west Oregon (Reeser et al., 2007). It has also been reported causing stem lesions on Italian alder (Alnus cordata) in California (Rooney-Latham et al., 2007). This is the first report of P. siskiyouensis in the UK and, to our knowledge, in Europe, and the first report of P. siskiyouensis causing stem cankers on A. incana. Its occurrence within a recently-planted site suggests a possible origin on introduced nursery stock. P. siskiyouensis has the potential to cause further damage to Alnus spp. and other plant species in Europe. Its comparative pathogenicity on various alder species is under investigation.

1 aPérez-Sierra, A1 aKalantarzadeh, M.1 aSancisi-Frey, S.1 aBrasier, C.M. uhttp://www.ndrs.org.uk/contents.php?vol=31http://www.ndrs.org.uk/article.php?id=03101701849nas a2200157 4500008004100000022001400041245005600055210005600111260001600167300002000183520136400203100001901567700002001586700001901606856006601625 2015 eng d a0031-949X00aTemporal Epidemiology of Sudden Oak Death in Oregon0 aTemporal Epidemiology of Sudden Oak Death in Oregon cFeb-04-2016 a1504141246310023 a

An effort to eradicate Phytophthora ramorum , causal agent of sudden oak death, has been underway since its discovery in Oregon forests. Using an information-theoretical approach we sought to model yearly variation in the size of newly infested areas and dispersal distance. Maximum dispersal distances were best modeled by spring and winter precipitation two years before detection, and infestation size the year prior. Infestation size was best modeled by infestation size and spring precipitation the year prior. In our interpretation, there is a two year delay between the introduction of inoculum and onset of mortality for a majority of sites. The year-long gap in between allows ample time for the production of inoculum contributing to the spread of P. ramorum. This is supported by epidemic development following changes in eradication protocols precipitated by an outbreak in 2011, attributable to a 2009 treatment delay and an uncharacteristically wet spring in 2010. Post-eradication, we have observed an increase in the total area of new outbreaks and increased frequency in dispersal distances greater than 4 km. While the eradication program has not eliminated P. ramorum from Oregon forests it has likely moderated this epidemic, emphasizing the need for prompt treatment of future invasive forest pathogens.

1 aPeterson, Ebba1 aHansen, Everett1 aKanaskie, Alan uhttp://apsjournals.apsnet.org/doi/10.1094/PHYTO-12-14-0348-FI04968nas a2200217 4500008004100000022001400041245013400055210006900189260001600258520420400274100002304478700002804501700001704529700002304546700002004569700001904589700002104608700002604629700002404655856007104679 2022 eng d a0191-291700aFirst report of the NA2 clonal lineage of the sudden oak death pathogen, Phytophthora ramorum, infecting tanoak in Oregon forests0 aFirst report of the NA2 clonal lineage of the sudden oak death p cFeb-02-20223 a

Phytophthora ramorum Werres, de Cock & Man in’t Veld, causal agent of sudden oak death (SOD) and ramorum leaf blight, is comprised of four clonal lineages in its invasive ranges of North America and Europe (Grünwald et al. 2012, Van Poucke et al. 2012). Of these, three – the NA1, NA2, and EU1 lineages – are found in U.S. nurseries, but only two, the NA1 and EU1 lineages, have been found infecting trees in North American forests (Grünwald et al. 2012, 2016). In the spring of 2021, tanoak (Notholithocarpus densiflorus Manos, Cannon & Oh) displaying symptoms consistent with SOD were detected north of Port Orford (Curry County, Oregon). Symptoms were canopy dieback and blackened petiole and stem lesions on tanoak sprouts. The pathogen isolated on PAR (CMA plus 200 ml/L ampicillin, 10 mg/L rifamycin, 66.7 mg/L PCNB) selective media was determined to be P. ramorum based on characteristic morphology of hyphae, sporangia, and chlamydospores (Werres et al. 2001). Positive identification as P. ramorum was obtained with a lineage-specific LAMP assay targeting an NA2 orphan gene, indicating the presence of the NA2 lineage. NA2 was confirmed by sequencing a portion of the cellulose binding elicitor lectin (CBEL) gene using CBEL5U and CBEL6L primers (Gagnon et al. 2014). Sequences (GenBank accessions MZ733981 and MZ733982) were aligned against reference sequences for all lineages (Gagnon et al. 2014) confirming the presence of NA2. Lineage determination as NA2 was further confirmed at eleven SSR loci (ILVOPrMS145, PrMS39, PrMS9C3, ILVOPrMS79, KI18, KI64, PrMS45, PrMS6, ILVOPrMS131, KI82ab, and PrMS43) using the methods of Kamvar et al. (2015). We completed Koch’s postulates using potted tanoaks, wound-inoculated at the midpoint of 1-year old stems with either hyphal plugs or non-colonized agar (n=4 per treatment). Tanoaks were maintained in a growth chamber (20°C-day / 18°C-night temperatures) with regular watering and an 18-photoperiod using F32T8 fluorescent bulbs (Phillips, Eindhoven, The Netherlands). After 7 days, brown to black lesions 1.2 to 2.9 cm in length were observed on the inoculated stems, from which P. ramorum was subsequently re-isolated; no symptoms were observed on the controls, and no pathogens were recovered when plating the wound sites in PAR. This is the first detection of the NA2 lineage causing disease in forests worldwide. The outbreak was found on private and public lands in forests typical to the SOD outbreak in Oregon (mixed conifer and tanoak), and was 33 km north of the closest known P. ramorum infestation. Follow-up ground surveys on adjacent lands have identified over 100 P. ramorum-positive tanoak trees, from which additional NA2 isolates have been recovered from bole cankers. NA2 is thought to be more aggressive than the NA1 lineage (Elliott et al. 2011), which has been present in Curry County since the mid-1990s (Goheen et al. 2017). Eradication of the NA2 lineage is being pursued to slow its further spread and prevent overlap with existing NA1 and EU1 populations. The repeated introductions of novel lineages into the western United States native plant communities highlights the vulnerability of this region to Phytophthora establishment, justifying continued monitoring for P. ramorum in nurseries and forests. References • Elliott, M, et al. 2011. For. Path. 41:7. https://doi.org/10.1111/j.1439-0329.2009.00627.x • Gagnon, M.-C., et al. 2014. Can. J. Plant Pathol. 36:367. https://doi.org/10.1080/07060661.2014.924999 • Goheen, E.M., et al. 2017. For. Phytophthoras 7:45. https://doi: 10.5399/osu/fp.7.1.4030 • Grünwald, N. J., et al. 2012. Trends Microbiol. 20:131. https://doi.org/10.1016/j.tim.2011.12.006 • Grünwald, N. J., et al. 2016. Plant Dis. 100:1024. https://doi.org/10.1094/PDIS-10-15-1169-PDN • Kamvar, Z.N. et al. 2015. Phytopath. 105:982. https://doi.org/10.1094/PHYTO-12-14-0350-FI • Van Poucke, K., et al. 2012. Fungal Biol. 116:1178. https://doi.org/10.1016/j.funbio.2012.09.003 • Werres, S., et al. 2001. Mycol. Res. 105: 1155. https://doi.org/10.1016/S0953-7562(08)61986-3

1 aPeterson, Ebba, K.1 aSondreli, Kelsey, Liann1 aReeser, Paul1 aNavarro, Sarah, M.1 aNichols, Casara1 aWiese, Randall1 aFieland, Valerie1 aGrünwald, Niklaus, J1 aLeBoldus, Jared, M. uhttps://apsjournals.apsnet.org/doi/pdf/10.1094/PDIS-10-21-2152-PDN03040nas a2200169 4500008004100000022001300041245012800054210006900182260001600251300001200267490000800279520245800287100001902745700002002764700002002784856006602804 2014 eng d a0378112700aSource or sink? The role of soil and water borne inoculum in the dispersal of Phytophthora ramorum in Oregon tanoak forests0 aSource or sink The role of soil and water borne inoculum in the  cJan-06-2014 a48 - 570 v3223 a

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 the case for the management of the phytopathogen, Phytophthora ramorum, causal agent of sudden oak death (SOD) of oaks and tanoaks. To detect P. ramorum, The Oregon SOD eradication program has relied upon the aerial observation of dead, overstory tanoak (Notholithocarpus densiflorus), an easily infected host widely distributed throughout the range of P. ramorum in Oregon. At risk is the possibility of misrepresenting the distribution of SOD, particularly if inoculum is predominately moved in soil and water, common dispersal pathways for other Phytophthora spp. To assess this risk, we performed surveys of understory vegetation in areas with a high risk of establishment of understory infection from soil and water sources: along roadsides within heavily trafficked areas with a history of SOD, and along streams known to contain P. ramorum inoculum. Additionally, we tested the alternative hypothesis of aerial dispersal, whereby infection in the understory would be spatially correlated with overstory mortality. Consistent with prior studies into the spatial structure of P. ramorum in Oregon, we found no evidence of understory infection in close proximity to roads in the absence of overstory mortality. Similarly, P. ramorum was only isolated from understory vegetation associated with streams when within close proximity to overstory sources, and more commonly further away from stream edges than within the splash and flood line. Both disease patterns are inconsistent with a dominate soil and water mediated dispersal mechanism. Rather, we found evidence supporting our alternative hypothesis of aerial dispersal whereby recovery of P. ramorum in the understory declined with increasing distance from the only known overstory source. These results support the use of aerial detection in describing the distribution of SOD in Oregon, and give further support to dispersal of inoculum in blowing fog or rain at scales not yet described for other forest Phytophthora species.

1 aPeterson, Ebba1 aHansen, Everett1 aHulbert, Joseph uhttp://linkinghub.elsevier.com/retrieve/pii/S037811271400126102104nas a2200181 4500008004100000022001400041245010100055210006900156260001600225300001600241490000800257520150500265100002301770700002001793700002001813700002301833856006601856 2020 eng d a0191-291700aRoot Rot of Juniperus and Microbiota by Phytophthora lateralis in Oregon Horticultural Nurseries0 aRoot Rot of Juniperus and Microbiota by Phytophthora lateralis i cJan-05-2020 a1500 - 15060 v1043 a

Widespread symptoms of root rot and mortality on Juniperus communis and Microbiota decussata were observed in two horticultural nurseries in Oregon, leading to the isolation of a Phytophthora sp. from diseased roots. Based on morphology and sequencing the internal transcribed spacer ITS1-5.8S-ITS2 region, isolates were identified as the invasive pathogen Phytophthora lateralis, causal agent of Port-Orford-cedar (POC; Chamaecyparis lawsoniana) root disease. Additional sequencing of the cytochrome c oxidase subunit 1 and 2 genes identified all isolates as belonging to the PNW lineage. Utilizing recovered isolates plus a POC-wildlands isolate and susceptible POC as controls, we completed Koch's postulates on potted Juniperus and Microbiota plants. Nursery isolates were more aggressive than the forest isolate, which was used in the POC resistance breeding program. Increased aggressiveness was confirmed using a branch stem dip assay with four POC clones that differed in resistance, although no isolate completely overcame major-gene resistance. Isolates were sensitive to mefenoxam, a fungicide commonly used to suppress Phytophthora spp. growth in commercial nurseries. Although POC resistance is durable against these more aggressive nursery isolates, the expanded host range of P. lateralis challenges POC conservation through the continued movement of P. lateralis by the nursery industry.

1 aPeterson, Ebba, K.1 aRupp, Franziska1 aEberhart, Joyce1 aParke, Jennifer, L uhttps://apsjournals.apsnet.org/doi/10.1094/PDIS-04-19-0808-RE01195nas a2200121 4500008004100000245006500041210005900106260006300165520070800228100002200936700002300958856009200981 2019 eng d00aSudden oak death, sudden larch death, and ramorum blight​ 0 aSudden oak death sudden larch death and ramorum blight aSt. Paul, MNbThe American Phytopathological Societyc20193 a

Phytophthora ramorum is a recently emerged pathogen with a host range of more than 150 plant species. This fungus-like organism causes sudden oak death on certain members of the oak family and has killed an estimated 30-45 million trees in coastal forests of California and Oregon. The pathogen additionally causes sudden larch death of Japanese larch, especially in conifer plantations in the United Kingdom. On most hosts, however, P. ramorum causes ramorum leaf blight or shoot blight on native plant species and horticultural nursery crops, plaguing some nurseries in California, Oregon, Washington, British Columbia and Europe. 

1 aPeterson, Ebba, K1 aParke, Jennifer, L uhttps://www.apsnet.org/edcenter/disandpath/oomycete/pdlessons/Pages/SuddenOakDeath.aspx04226nas a2200181 4500008004100000022001400041245007600055210007000131260001600201300001400217490000800231520364300239100002203882700002303904700002103927700003003948856006603978 2017 eng d a0191-291700aFirst Report of Phytophthora × multiformis on Alnus glutinosa in Spain0 aFirst Report of Phytophthora × multiformis on Alnus glutinosa in cJan-01-2017 a261 - 2610 v1013 a

Alder species are threatened by a lethal disease caused by the oomycete Phytophthora alni, one of the most important emergent pathogens of natural ecosystems in Europe during the last 20 years (Aguayo et al. 2014). Phytophthora alder decline has caused substantial economic losses and ecological damage from riparian alder populations. Initially, three different subspecies had been described, P. alni subsp. alni, P. alni subsp. uniformis, and P. alni subsp. multiformis. Recently, they have been raised to species status and renamed P. × alni, P. uniformis, and P. × multiformis, respectively (Husson et al. 2015). P. × alni was reported to be the most aggressive and pathogenic to alders. The other two species appear to be less aggressive, but are also considered pathogenic (Brasier and Kirk 2001). In Spain, P. × alni and P. uniformis has also been detected (Pintos Varela et al. 2012). In April 2014, crown dieback and mortality of Alnus glutinosa were noted across the riparian area along the Muiños River in Galicia (northwest Spain). Affected trees, showing abnormally small, yellow, and sparse leaves and necrotic lesions in the inner bark, were surveyed. Samples of bark including the cambium from active lesions, roots, and soil were collected. Phytophthora spp. were baited from saturated rhizosphere soil using carnation petals. Roots and tissue from fresh active inner bark lesions were plated onto selective medium V8-PARPH agar and incubated for 7 days at 22°C in the dark. A Phytophthora sp. isolated from root and bark was transferred to carrot agar (CA) and incubated in the dark. Colonies on CA were irregular with upper temperature limits for growth at 30°C. The isolates were homothallic, with smooth to extremely ornamented oogonia. Oogonial diameters ranging from 42 to 59 µm and one or two celled amphigynous antheridia were observed. In soil extract, noncaducous, nonpapillate, ellipsoid to ovoid sporangia were produced. Amplification of DNA was accomplished by using SCAR-PCR primers (Ioos et al. 2005). DNA samples of Phyophthora isolates have amplified using primers pairs PAM-F/R and PA-F/R. No amplicon was obtained using PAU-F/R primers. ITS (DC6-ITS6/ITS4) and nadh1 (NADHF1/NADHR1) mitochondrial gene regions were also amplified and deposited in GenBank (accession nos. KX090045 and KX090044 isolate CECT 20954). Comparison of the sequences showed 100% homology with P. × multiformis (KJ755099 and FJ696567). Pathogenicity of P. × multiformis isolate CECT 20954 was performed by inoculating 10 3-year-old A. glutinosa plants growing in pots. One shallow cut was made at the root collar level. A colonized 5-mm mycelial agar plug from a 7-day-old culture was inserted in every wound and sealed with Parafilm. Five control plants were inoculated with a sterile agar plug. Plants were maintained in a controlled chamber at 24°C and 80% humidity for 2 months. After a 5-week incubation period, inoculated plants showed dieback symptoms and necrosis of the inner bark tissue. Lesion lengths ranged from 2 to 10 cm. Control plants remained symptomless. P. × multiformis was recovered from all inoculated plants, but not from controls. To our knowledge, this is the first report of P. × multiformis in Spain. With this report, the detection of the P. alni species complex in Spain has been completed.

1 aPintos-Varela, C.1 aRial-Martínez, C.1 aAguín-Casal, O.1 aMansilla-Vázquez, J., P. uhttp://apsjournals.apsnet.org/doi/10.1094/PDIS-08-16-1092-PDN00469nas a2200109 4500008004100000245006200041210006200103260007600165300002200241100003400263856006200297 2002 eng d00aGround verification of Aerial survey for POC root disease0 aGround verification of Aerial survey for POC root disease bPNW Research Station, USDA Forest Service, Forestry Sciences Laboratory aTwo page brochure1 aPNW Research Station, USDA-FS uhttp://www.fs.fed.us/pnw/publications/brochure-misc.shtml01864nas a2200145 4500008004100000245012800041210006900169300001400238490000700252520135900259100001201618700001401630700001701644856005701661 2009 eng d00aEffectiveness of aluminum-fosetyl in the control of early nutfall of coconut tree due to Phytophthora katsurae (Pythiaceae)0 aEffectiveness of aluminumfosetyl in the control of early nutfall a123–1330 v153 a

Early nut fall and bud rot due to Phytophthora katsurae are the most important diseases of coconut tree observed in recent years at the Assinie plantations of PALMINDUSTRIE Company, Côte d’Ivoire. Field investigations conducted in 1983 revealed a high rate of nut fall (50-70%) during the rainy season. Cutting of coconut stands with rotten buds, as a way to control the spread of Oryctes sp., allowed to assess the number of dead trees over 139 and 89 ha of land for the hybrids and Grand West cultivars, respectively. In addition to those disease control measures proposed by the Company, comparison trials were systematically carried out using 2 fungicides: aluminum-fosetyl [fosetyl] at 3 doses (3.2, 4.8 and 6.4 g of active ingredient/tree) and Ridomil [metalaxyl] at one dose (3.125 g of active ingredient/tree). These fungicide were injected into the stem of the coconut every 3 months starting from December 1984. After 3 years, the efficacy of the 3 doses of aluminium-fosetyl over Ridomil in significantly reducing nut fall, even at low rates (3.2 g of active ingredient/tree), was apparent. However, the technique still remains out of reach of most farmers because of lack of technical know-how. It appears therefore, that an improvement of the technique, so as to make it accessible to the farmers, is a necessity.

1 aPohe, J1 aDongo, BK1 aN’Goran, N uhttp://www.ajol.info/index.php/aga/article/view/163300932nas a2200121 4500008004100000245011700041210006900158300001200227490001600239520040700255100001200662856013600674 1999 eng d00aFactors involved in the development of nutfall [Cocos nucifera nuts] due to Phytophthora katsurae in Ivory Coast0 aFactors involved in the development of nutfall Cocos nucifera nu a150-1530 v16/17 No. 33 aNut rot on coconut can be spread simply by contact or by spreading agents which maintain isolated infections within a bunch on a given tree and at plot level. The disease generally spreads horizontally from one bunch to another and vertically, particularly vertically downwards, from one nut to another in a given bunch. The positive effect of water and insects in disease spread has been demonstrated.1 aPohe, J uhttps://forestphytophthoras.org/references/factors-involved-development-nutfall-cocos-nucifera-nuts-due-phytophthora-katsurae-ivory04718nas a2200169 4500008004100000022001400041245010900055210006900164260001600233300002000249520414900269100001604418700001404434700001704448700001604465856006704481 2017 eng d a0191-291700aFirst report of alder Phytophthora cosely related to P. uniformis on Alnus glutinosa seedling in Finland0 aFirst report of alder Phytophthora cosely related to P uniformis cApr-12-2017 aPDIS-03-17-03223 a

The allotriploid Phytophthora × alni (Brasier & S.A. Kirk) Husson, Ioos & Marcais and its progenitors, the diploid P. uniformis (Brasier & S.A. Kirk) Husson, Ioos & Aguayo and the allotetraploid P. × multiformis (Brasier & S.A. Kirk) Husson, Ioos & Frey are the causal agents of alder decline in Europe. In June 2015, a dark, ∼40 mm stem lesion was found on one out of 100 inspected Alnus glutinosa (L.) Gaertn seedlings in Mäntyharju, Finland. Surface wood pieces from the lesion edges were plated onto malt agar. Cultures on carrot piece agar (CPA) showed an appressed colony with woolly aerial mycelium. Oogonia (Ø mean 44.8 µm, n = 50) and oospores (Ø mean 40.0 µm, n = 50) developed after 7 days at 20°C in the dark. They were commonly smooth walled, and 49 out of 50 of the amphigynous antheridia were single celled. Sporangia (21.7 × 18.1 µm, n = 50) were produced on pea broth, with 2-day flooding with soil extract, and they were commonly unpapillate and obpyriform-ellipsoidal. DNA was extracted, and the internal transcribed spacer (ITS) rDNA was amplified (ITS6 and ITS4; Cooke et al. 2000). The PCR products were then cloned because of double peaks in the sequence. Among 33 clones, four alleles with five polymorphic bases were obtained (A1, 55%; A2, 6%; A3, 15%; and A4, 24%; these were deposited in GenBank as accession nos. MF356294, MF356295, MF356296, and MF356297, respectively). The closest match to the ITS allele sequences in GenBank was the very closely related species P. cambivora AF087479 (differences, 7 to 9 bases). All other sequenced regions showed single alleles. The mitochondrial cox spacer (MF356298; amplified by FMPhy8 and FMPhy10, Martin et al. 2004) matched 100% with P. cambivora P1431 (GU221955) and P. alni P16202 (GU221933) in GenBank. A partial beta tubulin gene (MF356299; amplified by 901F and 1401R, Bilodeau et al. 2007) matched 100% with P. uniformis ALN58 (KU899249). ASF-like, GPA1, RAS-Ypt, and TRP1 genes were amplified with primers by Ioos et al. (2006). GPA1 (MF356301) matched 100% with P. uniformis PAU84 (DQ092849), and RAS-Ypt (MF356302) had exact matches with four P. uniformis isolates in GenBank (e.g., PANM53 and EU371549). The TRP1 gene (MF356303) differed by 1 base from P. uniformis alleles PAU60 (DQ202480) and PAU89 (DQ202481). The ASF-like gene (MF356300) matched 100% with PAU84 (DQ092815). Nine 1-year-old seedlings of A. glutinosa and of Betula pendula Roth were inoculated with plugs from 10-day-old mycelial culture on CPA after making a bark incision. Nine control seedlings of each species received a sterile CPA plug. Inoculations were wrapped in damp cotton wool, and the plants were kept outdoors at 10 to 22°C. After 15 days, eight out of nine (89%) A. glutinosa seedlings had developed lesions (mean length 22 mm), as well as six out of nine (67%) B. pendula seedlings (mean length 4 mm). No lesions were observed in control seedlings. The pathogen was reisolated from two symptomatic seedlings of both hosts. This is the first report of an alder Phytophthora in Finland. The sequence data suggested the isolate to be closely related but dissimilar to P. uniformis. The morphology corresponded to that previously reported for P. uniformis (Brasier et al. 2004), except for the antheridia, which were almost all single celled. Multiple ITS alleles could also refer to the initially reported P. uniformis karyotype 2n+2 (Brasier et al. 2004). These findings add to our knowledge on the variation among the alder Phytophthora group. Furthermore, they demonstrate the risk that the pathogen could be transported in new hosts.

1 aPoimala, A.1 aWerres, S1 aPennanen, T.1 aHantula, J. uhttps://apsjournals.apsnet.org/doi/10.1094/PDIS-03-17-0322-PDN01723nas a2200157 4500008004100000245011500041210006900156300001200225490000700237520112500244100001501369700001401384700001601398700001901414856013201433 1976 eng d00aIdentity and pathogenicity of species of Phytophthora causing root rot of Douglas-fir in the Pacific Northwest0 aIdentity and pathogenicity of species of Phytophthora causing ro a710-7140 v663 a

Three species of Phytophthora previously unreported from Douglas-fir were isolated along with P. cinnamomi from diseased trees from forest nurseries, forest outplanting sites, and seedling storage facilities in western Oregon and Washington. Two species were identified as P. cryptogea and P. drechsleri on the basis of sporangial and colony morphology, temperature-growth relations, and by comparisons with isolates of known identity. A third species, designated Phytophthora sp. 1, did not correspond to any previously described species. Phytophthora cinnamomi and P. cryptogea were highly virulent on dormant and growing Douglas-fir seedlings in greenhouse tests. Phytophthora drechsleri and Phytophthora sp. 1 appeared to be less virulent. Phytophthora cryptogea, P. drechsleri and Phytophthora sp. 1 are similar to P. lateralis, a destructive pathogen of Port-Orford-cedar, in growth at low temperatures and should therefore be regarded as potentially dangerous forest pathogens in cool, moist sites.

1 aPratt, R G1 aRoth, L F1 aHansen, E M1 aOstrofsky, W D uhttps://forestphytophthoras.org/references/identity-and-pathogenicity-species-phytophthora-causing-root-rot-douglas-fir-pacific05784nas a2200205 4500008004100000022001400041245007800055210006900133260001600202300000900218490000800227520517100235100001805406700001705424700001605441700001805457700001405475700002205489856006705511 2020 eng d a0191-291700aFirst Report of the NA2 Clonal Lineage of Phytophthora ramorum in Indiana0 aFirst Report of the NA2 Clonal Lineage of Phytophthora ramorum i cApr-20-2020 a18750 v1043 a

The oomycete pathogen Phytophthora ramorum is the causal agent of ramorum leaf blight and sudden oak death (Rizzo et al. 2002). P. ramorum is known to cause leaf blight and stem dieback on nursery hosts including Rhododendron. The disease typically results in dark, brownish lesions on leaves or stems, which can cause wilting and death of the plant (Grünwald et al. 2008; Werres et al. 2001). Since the emergence of the disease, a federal quarantine was established to prevent the spread of the pathogen, and nurseries that export P. ramorum hosts are subject to a federally mandated certification program for interstate export (Grünwald et al. 2012). This disease has had a significant impact on the U.S. nursery industry via quarantine regulations imposed on nurseries infested with the pathogen. The pathogen has been introduced at least three times into the Western United States as clonal lineages NA1, NA2, and EU1 (Grünwald et al. 2009, 2019; Ivors et al. 2006). In the spring and summer of 2019, USDA-APHIS reported that a shipment of potentially P. ramorum-infested plants was delivered to several Eastern and Midwestern states. Rhododendron leaves from numerous counties in Indiana, showing characteristic necrotic leaf blight symptoms, were sampled by Indiana Department of Natural Resources (IDNR) nursery inspectors between April 18 and June 3, 2019. These samples were initially screened for the presence of Phytophthora at the Purdue Plant and Pest Diagnostic Laboratory using an ELISA test (Agdia). Subsamples from tissue producing a positive ELISA result were forwarded to the Michigan State University Plant & Pest Diagnostics laboratory for P. ramorum-specific PCR testing, which was later confirmed by USDA CPHST. Leaf surfaces of P. ramorum-positive samples were surface disinfested to remove contaminating organisms by washing vigorously in 50 ml of 70% ethanol for 10 s followed by three rinses in sterile water. Washed leaves were blotted dry on sterile paper towels. From each leaf, 5-mm leaf discs were punched out of the leading edge of leaf lesions, and the resulting leaf discs were submerged in selective V8 medium amended with pimaricin, ampicillin, and rifampicin in Petri dishes. Petri dishes were incubated at 20°C until growth was present. A plug of growth from the leading edge of the resulting colony was transferred to fresh V8 medium containing a 47-mm 0.4-micron polycarbonate filter (Nucleopore) and incubated for approximately 8 days at 20°C. DNA was extracted by the Center for Genome Research and Biocomputing at Oregon State University using the Omega BioTek Plant DNA DS kit (M1130), and part of the cellulose binding elicitor lectin gene (CBEL) was amplified and sequenced with primers CBEL5U and CBEL6L (Gagnon et al. 2014). Sequences were aligned with the CBEL reference sequences of EU1 (KF679685), EU2 (KF679716), NA1 (EU688908), and NA2 (KF679712) (Gagnon et al. 2014). All 26 of the Indiana isolates were unambiguously classified as belonging to the NA2 clonal lineage (GenBank accessions MN601787 to MN601812). This is the first report of the NA2 clonal lineage outside of British Columbia, Washington, and California, indicating that this pathogen was most likely moved West to East. Prior documented lineages detected obtained from P. ramorum-infected plants in Eastern receiving states have only harbored the NA1 clonal lineage (Goss et al. 2009, 2011). As a result of these detections, the IDNR ordered destruction of more than 6,100 Rhododendron plants at retail outlets in Indiana.

1 aPress, C., M.1 aFieland, V J1 aCreswell, T1 aBonkowski, J.1 aMiles, L.1 aGrünwald, N., J. uhttps://apsjournals.apsnet.org/doi/10.1094/PDIS-12-19-2543-PDN02579nas a2200181 4500008004100000245011000041210006900151260001200220300001600232490000700248520199700255100001602252700001902268700001602287700001602303700001502319856006302334 2013 eng d00aPhytophthora diversity and the population structure of Phytophthora ramorum in Swiss ornamental nurseries0 aPhytophthora diversity and the population structure of Phytophth c10/2013 a1063–10710 v623 a

Invasive oomycete pathogens have been causing significant damage to native ecosystems worldwide for over a century. A recent well-known example is Phytophthora ramorum, the causal agent of sudden oak death, which emerged in the 1990s in Europe and North America. In Europe, this pathogen is mainly restricted to woody ornamentals in nurseries and public greens, while severe outbreaks in the wild have only been reported in the UK. This study presents the results of the P. ramorum survey conducted in Swiss nurseries between 2003 and 2011. In all 120 nurseries subjected to the plant passport system, the main P. ramorum hosts were visually checked for above ground infections. Phytophthora species were isolated from tissue showing symptoms and identified on the basis of the morphological features of the cultures and sequencing of the ribosomal ITS region. Phytophthora was detected on 125 plants (66 Viburnum, 58 Rhododendron and one Pieris). Phytophthora ramorum was the most frequent species (59·2% of the plants), followed by P. plurivora, P. cactorum, P. citrophthora, P. cinnamomi, P. cactorum/P. hedraiandra, P. multivora and P. taxon PgChlamydo. The highest incidence of P. ramorum was observed on Viburnum × bodnantense. Microsatellite genotyping showed that the Swiss P. ramorum population is highly clonal and consists of seven genotypes (five previously reported in Europe, two new), all belonging to the European EU1 clonal lineage. It can therefore be assumed that P. ramorum entered Switzerland through nursery trade. Despite sanitation measures, repeated P. ramorum infections have been recorded in seven nurseries, suggesting either reintroduction or unsuccessful eradication efforts.

1 aProspero, S1 aVercauteren, A1 aHeungens, K1 aBelbahri, L1 aRigling, D uhttps://onlinelibrary.wiley.com/doi/full/10.1111/ppa.1202701776nas a2200169 4500008004100000245012300041210006900164260001600233300001400249490000800263520117000271100002601441700001401467700002601481700002001507856007901527 2018 eng d00aSurvival of Phytophthora cinnamomi and Fusarium verticillioides in commercial potting substrates for ornamental plants0 aSurvival of Phytophthora cinnamomi and Fusarium verticillioides  cJan-08-2018 a484 - 4930 v1663 a

Live plants, particularly when accompanied by soil or potting substrates, are considered the main pathway for international spread of plant pathogens. Modern, rapid shipping technologies for international plant trade increase the probability of plant pathogen survival during transport and the subsequent chances of disease outbreaks in new locations. The survival of two model pathogens, an Oomycete, Phytophthora cinnamomi, and a filamentous fungus, Fusarium verticillioides, was studied in two different commercial potting substrates (peat and peat‐free) under glasshouse conditions in the absence of a plant host. Survival rates were analysed at 2, 7, 12 and 17 months after substrate inoculation. Fusarium verticillioides had the longest survival rate, and was still present at 17 months. In contrast, P. cinnamomi survived up to 7 months but was not recovered after 12 or 17 months. There was no significant difference in the number of colony‐forming units (CFUs) of either pathogen in the two substrates, except at 2 months, when higher numbers were recovered from peat substrates.

1 aPuértolas, Alexandra1 aBoa, Eric1 aBonants, Peter, J. M.1 aWoodward, Steve uhttps://onlinelibrary.wiley.com/doi/abs/10.1111/jph.12708?campaign=woletoc02734nas a2200193 4500008004100000022001400041245018600055210006900241260001100310300001400321490000700335520203500342100002102377700002102398700001702419700001902436700002102455856006402476 2013 eng d a1387-354700aChallenges in predicting invasive reservoir hosts of emerging pathogens: mapping Rhododendron ponticum as a foliar host for Phytophthora ramorum and Phytophthora kernoviae in the UK0 aChallenges in predicting invasive reservoir hosts of emerging pa c3/2013 a529 - 5450 v153 a

Invasive species can increase the susceptibility of ecosystems to disease by acting as reservoir hosts for pathogens. Invasive hosts are often sparsely recorded and not in equilibrium, so predicting their spatial distributions and overlap with other hosts is problematic. We applied newly developed methods for modelling the distribution of invasive species to the invasive shrub Rhododendron ponticum—a foliar reservoir host for the Phytophthora oomycete plant pathogens, P. ramorum and P. kernoviae, that threaten woodland and heathland habitat in Scotland. We compiled eleven datasets of biological records for R. ponticum (1,691 points, 8,455 polygons) and developed Maximum Entropy (MaxEnt) models incorporating landscape, soil and climate predictors. Our models produced accurate predictions of current suitable R. ponticum habitat (training AUC = 0.838; test AUC = 0.838) that corresponded well with population performance (areal cover). Continuous broad-leaved woodland cover, low elevation (<400 m a.s.l.) and intermediate levels of soil moisture (or Enhanced Vegetation Index) favoured presence of R. ponticum. The high coincidence of suitable habitat with both core native woodlands (54 % of woodlands) and plantations of another sporulation host, Larix kaempferi (64 % of plantations) suggests a high potential for spread of Phytophthora infection to woodland mediated by R. ponticum. Incorporating non-equilibrium modelling methods did not improve habitat suitability predictions of this invasive host, possibly because, as a long-standing invader, R. ponticum has filled more of its available habitat at this national scale than previously suspected.

1 aPurse, Bethan, V1 aGraeser, Philipp1 aSearle, Kate1 aEdwards, Colin1 aHarris, Catriona uhttp://link.springer.com/article/10.1007/s10530-012-0305-y#01973nas a2200157 4500008004100000245014000041210006900181300001200250490001400262520134300276100001601619700001501635700001401650700001401664856013701678 2011 eng d00aPhytophthora leaf blight - a new disease of California wax-myrtle (Morella californica) in Oregon, USA caused by a Phytophthora species0 aPhytophthora leaf blight a new disease of California waxmyrtle M aS57-S630 v41 Suppl.3 a

In spring, 2009, the Oregon State University Plant Clinic received reports of severe defoliation of California wax-myrtle plants (Morella californica (Cham. & Schlecht.) Wilbur) on the north-central coast of Oregon, in western North America. Isolations from necrotic leaf tissue yielded an organism which, from morphological characteristics and a genus-specific enzyme-linked immunosorbent assay, was identified as a species of the genus Phytophthora. Total DNA was extracted from hyphal tip-derived cultures from leaf or twig tissue and subjected to a polymerase chain reaction process aimed at species identification. Sequencing techniques revealed a 99.7% match with P. syringae although our isolates differed from published descriptions of this species in some respects. Inoculation of healthy plants with cultured mycelium resulted in symptoms similar to those originally observed in the field, and reisolations produced colonies of the same organism. This is the first report of a species of Phytophthora causing disease in M. californica. Leaf blight of California wax-myrtle is now widespread on the north-central coast of Oregon. This disease is serious and is adversely affecting the health of this native understory species which is frequently used for amenity plantings.

1 aPutnam, M L1 aSerdani, M1 aCurtis, M1 aAngima, S uhttps://forestphytophthoras.org/references/phytophthora-leaf-blight-new-disease-california-wax-myrtle-morella-californica-oregon-usa