TY - JOUR T1 - Phytophthora alni subsp. uniformis found in Alaska beneath thinleaf alders JF - Plant Health Progress Y1 - 2008 A1 - G. C. Adams A1 - M. Catal A1 - L. Trummer A1 - Hansen, E.M. A1 - P. Reeser A1 - J. J. Worrall AB -

Phytophthora alni Brasier & S. A. Kirk 2004 is an emergent pathogen causing a lethal root and collar disease of alder species in Europe. The species has not been previously found in North America, although an isolate tentatively referred to as P. alni was reported in a survey of nurseries in Minnesota. The potential establishment and spread of this complex of pathogens is perceived to represent a threat to all species of Alnus in the western hemisphere.

UR - http://www.plantmanagementnetwork.org/php/elements/sum2.aspx?id=7094 ER - TY - JOUR T1 - Strong genetic differentiation between North American and European populations of Phytophthora alni subsp. uniformis JF - Phytopathology Y1 - 2012 A1 - Aguayo, Jaime A1 - Adams, Gerard C. A1 - Halkett, Fabien A1 - Catal, Mursel A1 - Husson, Claude A1 - Nagy, Zoltán A. A1 - Hansen, Everett M. A1 - Benoît Marçais A1 - Pascal Frey AB -

Alder decline caused by Phytophthora alni has been one of the most important diseases of natural ecosystems in Europe during the last 20 years. The emergence of Phytophthora alni subsp. alni (Paa)—the pathogen responsible for the epidemic—is linked to an interspecific hybridization event between two parental species: Phytophthora alni subsp. multiformis (Pam) and Phytophthora alni subsp. uniformis (Pau). One of the parental species, Pau, has been isolated in several European countries and recently in North America. The objective of this work was to assess the level of genetic diversity, the population genetic structure, and the putative reproduction mode and mating system of Pau. Five new polymorphic microsatellite markers were used to contrast both geographical populations. The study comprised 71 isolates of Pau collected from 8 European countries and 10 locations in North America. Our results revealed strong differences between continental populations (Fst=0.88; Rst=0.74), with no evidence for gene flow. European isolates showed extremely low genetic diversity compared to the North American collection. Selfing appears to be the predominant mating system in both continental collections. The results suggest that the European Pau population is most likely alien and derives from the introduction of a few individuals, while the North American population probably is an indigenous population.

UR - http://dx.doi.org/10.1094/PHYTO-05-12-0116-R ER - TY - JOUR T1 - Potential of Phytophthora pinifolia to spread via sawn green lumber: a preliminary investigation JF - Southern Forests: a Journal of Forest Science Y1 - 2012 A1 - Ahumada, R. A1 - Rotella, A. A1 - Slippers, B. A1 - Wingfield, M. J. AB -

Phytophthora pinifolia causes the needle and shoot disease of Pinus radiata in Chile known as Daño Foliar del Pino. Although P. pinifolia is primarily a needle pathogen, there are concerns that it might be spread to new environments via the export of contaminated timber. In order to determine whether P. pinifolia can enter or persist in green sawn lumber, its presence in lumber produced from trees exposed to the pathogen for at least four years was examined. Green lumber produced from the infected trees, and green wood samples artificially exposed to P. pinifolia inoculum, were analysed by making extensive isolations on Phytophthora selective media. In addition, PCR was conducted using species-specific primers developed for P. pinifolia. Results of the study showed that the green sawn lumber taken from trees infected by P. pinifolia, or green lumber exposed in infected pine plantations, displayed no evidence of the pathogen surviving in this material.

VL - 74 UR - http://www.tandfonline.com/doi/abs/10.2989/20702620.2012.717381 ER - TY - JOUR T1 - Involvement of Phytophthora spp. in chestnut decline in the Black Sea region of Turkey JF - Forest Pathology Y1 - 2012 A1 - Akıllı, S. A1 - Serçe, U. A1 - Katırcıoğlu, Y. Z. A1 - Maden, S. AB -

Chestnut blight caused by Cryphonectria parasitica is a serious disease of Castanea sativa in the Black Sea region of Turkey. During disease surveys, dieback and decline symptoms were observed on trees without apparent blight and ink disease symptoms. Black necroses, similar to those caused by Phytophthora infections, were noted on some of the chestnut coppices and saplings in one nursery in Ordu and led to an investigation into this disease complex. Only symptomatic plants showing dieback symptoms were investigated. Soil samples together with fine roots were collected from two directions, north and north-east, approximately 150 cm away from the main stems. Phytophthora spp. were baited with young chestnut leaves. Three Phytophthora spp., P. cambivora, P. cinnamomi and P. plurivora, were identified from 12 soil samples collected from 73 locations, while from the nurseries, only P. cinnamomi was obtained. Phytophthora cinnamomi was the most common species, obtained from seven locations in five provinces and from four nurseries having similar symptoms mentioned above in different locations. Phytophthora cambivora and P. plurivora were less frequently obtained, from three to two stands, respectively. Phytophthora cinnamomi and P. cambivora were the most aggressive species when inoculated at the stem base on 3-year-old chestnut saplings, killing six saplings of eight inoculated in 2 months. The three Phytophthora species were first recorded on chestnut in Black sea region of Turkey with the limited samples investigated in a large area about 150 000 ha chestnut forest.

PB - Blackwell Publishing Ltd VL - 42 UR - http://dx.doi.org/10.1111/j.1439-0329.2012.00770.x ER - TY - JOUR T1 - Management of Phytophthora pod rot disease on cocoa farms in Ghana JF - Crop Protection Y1 - 2003 A1 - AY Akrofi A1 - AA Appiah A1 - IY Opoku AB -

From 1991 to 1997, field observations on trials involving the use of metalaxyl and copper-based fungicides were made on farmers’ farms in four Phytophthora megakarya affected cocoa growing regions of Ghana to control Phytophthora pod rot disease. Data on farm management practices, cocoa and shade tree types and densities, plot sizes, yield, land tenure and labour arrangements for farm operations, disease incidence and profitability of disease control were collected. Lower disease incidence and higher yields were recorded on fungicide-treated plots than on the untreated plots. The profitability of fungicide application depended on the level of farm management, nature of land tenure and labour arrangements for farm operations. The challenges involved in conducting trials with active participation by farmers are discussed. The involvement of farmers in the development of disease control programmes is crucial for subsequent adoption of the technology.

VL - 22 UR - http://www.sciencedirect.com/science/article/pii/S026121940200193X IS - 3 JO - Crop Protection ER - TY - Generic T1 - On-farm farmer managed trials to control black pod disease caused by Phytophthora megakarya in Ghana T2 - Proceedings of the First International Cocoa Pests and Disease Seminar Y1 - 1995 A1 - AY Akrofi A1 - IY Opoku A1 - AA Appiah JF - Proceedings of the First International Cocoa Pests and Disease Seminar PB - Owusu, G.K., Padi, B., Ollennu, L.A.A., Owusu Manu, E. (Eds.) CY - Accra, Ghana UR - http://dx.doi.org/10.4314/gjas.v33i2.1876 ER - TY - JOUR T1 - Phytophthora foot rot of black pepper in Brazil and Puerto Rico JF - Phytopathology Y1 - 1972 A1 - Alconero, R A1 - Albuquerque, F A1 - Almeyda, N A1 - Santiago, AG VL - 62 UR - http://www.apsnet.org/publications/phytopathology/backissues/Documents/1972Articles/Phyto62n01_144.PDF ER - TY - JOUR T1 - Lessons learned from a decade of sudden oak death in California: evaluating local management JF - Environmental Management Y1 - 2010 A1 - Alexander, Janice A1 - Lee, Christopher AB - Sudden Oak Death has been impacting California’s coastal forests for more than a decade. In that time, and in the absence of a centrally organized and coordinated set of mandatory management actions for this disease in California’s wildlands and open spaces, many local communities have initiated their own management programs. We present five case studies to explore how local-level management has attempted to control this disease. From these case studies, we glean three lessons: connections count, scale matters, and building capacity is crucial. These lessons may help management, research, and education planning for future pest and disease outbreaks. PB - Springer New York VL - 46 UR - http://dx.doi.org/10.1007/s00267-010-9512-4 N1 - 10.1007/s00267-010-9512-4 ER - TY - JOUR T1 - Defining plant resistance to Phytophthora cinnamomi: a standardized approach to assessment JF - Journal of Phytopathology Y1 - 2012 A1 - Allardyce, Jane A. A1 - Rookes, James E. A1 - Cahill, David M. KW - Phytophthora cinnamomi KW - resistance KW - root pathogen KW - Zea mays KW - zoospores AB -

Phytophthora cinnamomi is a soil-borne plant pathogen that causes devastating disease in agricultural and natural systems worldwide. While a small number of species survive infection by the pathogen without producing disease symptoms, the nature of resistance, especially under controlled conditions, remains poorly understood. At present, there are no standardized criteria by which resistance or susceptibility to P. cinnamomi can be assessed, and we have used five parameters consisting of plant fresh weight, root growth, lesion length, relative chlorophyll content of leaves and pathogen colonization of roots to analyse responses to the pathogen. The parameters were tested using two plant species, Zea mays and Lupinus angustifolius, through a time course study of the interactions and resistance and susceptibility defined 7 days after inoculation. A scoring system was devised to enable differentiation of these responses. In the resistant interaction with Z. mays, there was no significant difference in fresh weight, root length and relative chlorophyll content in inoculated compared with control plants. Both lesion size and pathogen colonization of root tissues were limited to the site of inoculation. Following inoculation L. angustifolius showed a significant reduction in plant fresh weight and relative leaf chlorophyll content, cessation of root growth and increased lesion lengths and pathogen colonization. We propose that this technique provides a standardized method for plant–P. cinnamomi interactions that could be widely used to differentiate resistant from susceptible species.

PB - Blackwell Publishing Ltd VL - 160 UR - http://dx.doi.org/10.1111/j.1439-0434.2012.01895.x ER - TY - JOUR T1 - Lavender Cotton Root Rot: A New Host of Phytophthora tentaculata Found in Spain JF - Plant Disease Y1 - 2006 A1 - Álvarez, L. A. A1 - Pérez-Sierra, A. A1 - León, M. A1 - Armengol, J. A1 - ía-Jiménez, J. AB -

Lavender cotton, Santolina chamaecyparissus, is an evergreen shrub growing primarily in dry, calcareous habitats and is grown in rock gardens and mixed borders mainly for its ornamental and aromatic foliage. During 2004, several commercial nurseries in Valencia Province (eastern Spain) reported high mortality of lavender cotton. The foliage of the diseased plants turned brown, wilted, and died. A Phytophthora sp. was isolated consistently from the soil and roots of infected plants using apple baits and the selective medium PARBH (1), respectively. Four pure cultures (PS-31, PS-32, PS-33, and PS-34) were established from hyphal tips and characterized. Colony morphology on potato dextrose agar (PDA) at 24°C was stoloniferous (short stubby branches) with a growth rate of 2.2 mm per day. Sporangia, chlamydospores, and oospores were produced on V8 agar. The sporangia were ovoid to obpyriform, 27.5 to 64.8 (48.3) × 25 to 52.5 (37.5) μm, length/breadth ratio of 1.3:1, and papillate, from which 20% were caducous with a short pedicel (<5 μm). Hyphal swellings and chlamydospores (22 to 38 μm in diameter) were present. Isolates were homothallic, oogonia were globose, mostly terminal 27.5 to 40 (36.2) μm in diameter, 88% of the antheridia were paragynous, monoclinous, or diclinous, and occasionally with two paragynous antheridia per oogonium. Amphigynous antheridia (12%) were also observed. Oospores were aplerotic, 25 to 35 (32.3) μm in diameter, and thin walled. These characteristics and measurements conformed to the description of P. tentaculata described by Kröber and Marwitz (2). Sequencing the internal transcribed spacer region of Santolina isolates PS-32 and PS-34 and comparison of these sequences with other sequences available in GenBank revealed that they were identical to P. tentaculata (AF266775). Pathogenicity tests used 10 4-to-5-month-old potted lavender cotton and two methods. In the first method, inoculum was prepared on a media of 200 g of oats and 120 ml of V8 juice to 1 liter of distilled water. The medium was inoculated with P. tentaculata grown on PDA and incubated in the dark at 20°C for 4 weeks. Inoculum was buried into the compost mixture around the roots at a rate of 3% (w/v). The second method applied a zoospore drench of 50 ml per plant (1 × 104 zoospores per ml) obtained by inducing zoospores in sterile soil extract from cultures of V8 juice agar. The control plants were inoculated with sterile media and sterile distilled water. The following day, the pots were flooded for 2 days, plants were maintained in a glasshouse at 24 ± 5°C, and watered twice a week. All plants inoculated with the first method had wilted foliage and died within 2 months after inoculation, while plants inoculated with zoospores died after 3 months. P. tentaculata was reisolated and the test was repeated twice. The control plants did not show any symptoms of the disease. P. tentaculata was first reported causing root and stalk rot on Chrysanthemum frutescens hybrids, C. leucanthemum, Delphinium ajacis, and Verbena hybrids in Germany (2). It has also been reported on Verbena hybrids in Spain (3). To our knowledge, this is the first report of P. tentaculata causing root rot on lavender cotton.

VL - 90 UR - http://apsjournals.apsnet.org/doi/abs/10.1094/PD-90-0523A IS - 4 JO - Plant Disease ER - TY - JOUR T1 - Caracterização morfofisiológica e análise de PCR-SSCP de isolados de Phytophthora da acácia-negra na região Sul do Brasil JF - Summa Phytopathologica Y1 - 2011 A1 - Alves, TCA A1 - Santos, A. F. dos A1 - Tessmann, DJ A1 - Vida, JB A1 - Harakava, Ricardo AB -

The aim of this study was to characterize Phytophthora isolates from black wattle (Acacia mearnsii) in Southern Brazil, based on phenotypic traits such as morphology, mycelial growth, cultural features, sexual compatibility and pathogenicity, as well as on single strand conformation polymorphism (PCR-SSCP) of rDNA ITS-gene 5.8S region. The isolates presented sporangia with prominent papilla, irregularly sympodial sporangia, heterothalic cultures with amphigynous antheridia, presence of chlamydospore and mycelial growth at temperature above 35°C, allowing the classification of all 12 isolates as P. nicotianae. All isolates were pathogenic to black wattle, causing necrosis on stems without gum formation, with significant differences on aggressiveness (P=0.05). Two populations of P. nicotianae from black wattle can be distinguished based on PCR-SSCP analysis of rDNA; however, this separation has no apparent correlation with phenotypic traits.

O objetivo do trabalho foi caracterizar isolados de Phytophthora da acácia-negra (Acacia mearnsii) provenientes do Sul do Brasil, com base em características fenotípicas tais como morfologia, crescimento micelial, características das culturas, compatibilidade sexual e patogenicidade, e em perfis de polimorfismo de conformação de fita simples (SSCP = Single Strand Conformation Polymorphism) da região ITS-gene 5.8S do rDNA. Os isolados apresentaram esporângios com papilas proeminentes, arranjo dos esporângios irregularmente simpodial, culturas heterotálicas com presença de anterídios anfígenos, presença de clamidósporos e crescimento micelial em temperatura acima de 35°C, permitindo a classificação dos 12 isolados como P. nicotianae. Todos os isolados foram patogênicos, causando necrose em ramos de acácia-negra, sem formação de goma, com diferenças significativas de agressividade (p=0,05). Duas populações podem ser distinguidas em P. nicotianae da acácia negra pela análise PCR-SSCP do rDNA; no entanto essa separação não apresenta aparente correlação com características fenotípicas.

VL - 37 UR - http://www.scielo.br/pdf/sp/v37n3/a02v37n3.pdf IS - 3 JO - Summa phytopathol. ER - TY - JOUR T1 - First Report of Gummosis Caused by Phytophthora frigida on Black Wattle in Brazil JF - Plant Disease Y1 - 2016 A1 - Alves, T. C. A. A1 - Tessmann, D. J. A1 - Ivors, K. L. A1 - Ristaino, J. B. A1 - Santos, A. F. dos AB -

Black wattle (Acacia mearnsii), a tree species native to Australia, is considered the main source of bark for the tannin industry worldwide. It is the third most cultivated forest species in Brazil. Gummosis, caused by Phytophthora spp., is a major disease affecting black wattle plantations in that country, where the disease incidence can reach 43%. The most common disease symptoms are lesions on the trunk, which may or may not be accompanied by gum exudation. Severe infection can lead to plant death. Phytophthora nicotianiae and P. bohemeriae were reported as causative agents of black wattle gummosis in Brazil (Santos et al. 2006). In South Africa, besides these species, P. meadii was also recorded on black wattle (Roux and Wingfield 1997), and P. frigida on green wattle (A. decurrens) (Maseko et al. 2007). A survey in 6-year-old black wattle plantations located in the Piratini and Cristal counties in the state of Rio Grande do Sul in 2008 revealed the occurrence of a third Phytophthora species causing gummosis on black wattle in Brazil, P. frigida. Twenty-four isolates were obtained, and all were identified as P. frigida based on morphological characteristics and the sequence of portions of the ITS-5.8S rDNA, and cox I and cox II genes. Morphological characterization of colonies on carrot agar medium (CA) revealed colonies of all isolates with dense aerial mycelium, and five different colony patterns were observed: stellate, cottony, petaloid-to-cottony, slightly stellated, and slightly rosaceous. The colony growth rate was 12 mm/day at 24 to 30°C. All isolates produced sporangia abundantly in 10% nonsterile soil extract when grown under constant light. Most of the sporangia had prominent papilla. Most isolates had persistent sporangia formed singly or in a loose sympodium. The sporangial shape was predominantly ovoid, though there were other shapes such as globose, ellipsoid, and obpyriform found in some isolates, including some distorted shapes. The dimensions of 50 sporangia ranged from 29 to 71 × 20 to 53 µm (avg. 46 × 33 µm), with length-to-breadth ratios of 1.3 to 1.5 (avg. 1.4). The isolates produced globose chlamydospores, terminal or intercalary, and measured 21 to 55 µm diameter (avg. 32 µm). Oogonium diameter ranged from 22 to 37 µm (avg. 30 µm). Antheridia were amphigynous and oospores were globose, aplerotic, and 18 to 31 µm (avg. 24 µm) in diameter. Portions of the ITS-5.8 gene rDNA (730 bp) and the cox I (650 bp) and cox II (650 bp) genes were amplified by PCR. BLAST search of the GenBank database revealed that the fragments for ITS-5.8S gene rDNA (KU570067), and cox I (KU570065), and cox II (KU570066) sequence fragments from isolate P92 were 99 to 100% similar with the accessions of P. frigida (Robideau et al. 2011). To confirm pathogenicity, the 24 isolates of P. frigida was used to inoculate 10 one-year-old black wattle plants. For inoculation, an agar mycelial plug from a 1-week-old colony on CA was put on the stem wound done with a cork borer (6 mm diam.). Necroses of stems were observed 4 weeks after inoculation with the presence, or absence, of gum exudation, as observed initially in the field. P. frigida was reisolated from each infected stem. This is the first report of P. frigida occurring in A. mearnsii worldwide.

VL - 100 UR - http://apsjournals.apsnet.org/doi/10.1094/PDIS-01-16-0134-PDN IS - 11 JO - Plant Disease ER - TY - JOUR T1 - Stand development patterns as a consequence of the mortality in Austrocedrus chilensis forests JF - Forest Ecology and Management Y1 - 2010 A1 - Amoroso, Mariano M. A1 - Larson, Bruce C. KW - Austrocedrus chilensis KW - mortality KW - Stand dynamics KW - Uneven-aged PB - {ELSEVIER SCIENCE BV} CY - {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS} VL - 259 ER - TY - JOUR T1 - Distinct Trophic Specializations Affect How Phytophthora ramorum and Clade 6 Phytophthora spp. Colonize and Persist on Umbellularia californica Leaves in Streams JF - Phytopathology Y1 - 2018 A1 - Aram, Kamyar A1 - Rizzo, David M. AB -

Phytophthora spp. are regularly recovered from streams but their ecology in aquatic environments is not well understood. Phytophthora ramorum, invasive in California forests, persists in streams at times when sporulation in the canopy is absent, suggesting that it reproduces in the water. Streams are also inhabited by resident, clade 6 Phytophthora spp., believed to be primarily saprotrophic. We conducted experiments to determine whether differences of trophic specialization exist between these two taxa, and investigated how this may affect their survival and competition on stream leaf litter. P. ramorum effectively colonized fresh (live) rhododendron leaves but not those killed by freezing or drying, whereas clade 6 species colonized all leaf types. However, both taxa were recovered from naturally occurring California bay leaf litter in streams. In stream experiments, P. ramorum colonized bay leaves rapidly at the onset; however, colonization was quickly succeeded by clade 6 species. Nevertheless, both taxa persisted in leaves over 16 weeks. Our results confirm that clade 6 Phytophthora spp. are competent saprotrophs and, though P. ramorum could not colonize dead tissue, early colonization of suitable litter allowed it to survive at a low level in decomposing leaves.

UR - https://apsjournals.apsnet.org/doi/pdf/10.1094/PHYTO-06-17-0196-R JO - Phytopathology ER - TY - JOUR T1 - Phytophthora cinnamomi A1: An ancient resident of New Guinea and Australia of Gondwanan origin? JF - Forest Pathology Y1 - 2017 A1 - Arentz, F. ED - Woodward, S. AB -

This article re-examines the hypothesis, first proposed by Shepherd (Search, 6(11-12), 1975, 484), that Phytophthora cinnamomi is an ancient organism in Australia and New Guinea. It further evaluates data that suggest the A1 mating type is Gondwanan in origin and may have been present in New Guinea for up to 10 million years. It is postulated that there has been a mating type change in P. cinnamomi from A1 to A2 in relatively recent times as a result of genetic transformation of the A1 mating type.

UR - http://doi.wiley.com/10.1111/efp.12342 IS - 41 JO - For. Path. ER - TY - JOUR T1 - Strains and taxonomy of Phytophthora palmivora Butler (P. Faberi Maubl.) JF - Transactions of the British Mycological Society Y1 - 1929 A1 - Ashby, S.F. VL - 14 UR - http://linkinghub.elsevier.com/retrieve/pii/S0007153629800253 IS - 1-2 JO - Transactions of the British Mycological Society ER - TY - Generic T1 - Environment Protection and Biodiversity Conservation Act 1999 Y1 - 1999 A1 - Australian Department of the Environment SN - 0 642 24863 3 UR - http://www.environment.gov.au/biodiversity/invasive/diseases/phytophthora-cinnamomi.html ER -