%0 Conference Proceedings %B Proceedings of the First International Cocoa Pests and Disease Seminar %D 1995 %T On-farm farmer managed trials to control black pod disease caused by Phytophthora megakarya in Ghana %A AY Akrofi %A IY Opoku %A AA Appiah %B Proceedings of the First International Cocoa Pests and Disease Seminar %I Owusu, G.K., Padi, B., Ollennu, L.A.A., Owusu Manu, E. (Eds.) %C Accra, Ghana %P pp. 109–118 %8 1997 %G eng %U http://dx.doi.org/10.4314/gjas.v33i2.1876 %R 10.4314/gjas.v33i2.1876 %0 Journal Article %J Nature %D 1992 %T Oak mortality in Iberia %A C.M. Brasier %B Nature %V 360 %P 539-539 %G eng %U http://www.nature.com/nature/journal/v360/n6404/abs/360539a0.html %R doi:10.1038/360539a0 %0 Journal Article %J Proceedings of the National Academy of Sciences of the United States of America %D 1999 %T Origin of a new Phytophthora pathogen through interspecific hybridization %A C.M. Brasier %A Cooke, D. E. L. %A Duncan, J. M. %X Plant disease epidemics resulting from introductions of exotic fungal plant pathogens are a well known phenomenon. An associated risk that accelerated pathogen evolution may be occurring as a consequence of genetic exchange between introduced, or introduced and resident, fungal pathogens is largely unrecognized. This is, in part, because examples of natural, interspecific hybridization in fungi are very rare. Potential evolutionary developments range from the acquisition of new host specificities to emergence of entirely new pathogen taxa. We present evidence from cytological behavior, additive nucleotide bases in repetitive internal transcribed spacer regions of the rRNA-encoding DNA (rDNA), and amplified fragment length polymorphisms of total DNA that a new, aggressive Phytophthora pathogen of alder trees in Europe comprises a range of heteroploid-interspecific hybrids involving a Phytophthora cambivora-like species and an unknown taxon similar to Phytophthora fragariae. The hybrids marked developmental instabilities, unusual morphological variability, and evidence for recombination in their internal transcribed spacer profiles indicates that they are of recent origin and that their evolution is continuing. The likelihood of such evolutionary events may be increasing as world trade in plants intensifies. However, routine diagnostic procedures currently in use are insufficiently sensitive to allow their detection. %B Proceedings of the National Academy of Sciences of the United States of America %V 96 %P 5878-5883 %G eng %U http://www.pnas.org/content/96/10/5878.abstract %R doi: 10.1073/pnas.96.10.5878 %0 Journal Article %J Phytopathology %D 1951 %T The occurrence of Phytophthora cinnamomi in the soil under pine stands in the southeast. %A Campbell, W.A. %B Phytopathology %V 41 %P 742-746 %G eng %0 Journal Article %J Ghana Jnl. Agric. Sci %D 1974 %T The occurrence of Phytophthora palmivora (Butl.) Butl. in soil in Ghana %A Dakwa, JT %X

The occurrence of Phytophthora palmivora (But!.) But!. in soil was studied over 2 consecutive years by baiting the fungus with healthy cocoa pods. The fungus was frequently found in soils of a forest reserve, an abandoned cocoa farm and in farms still under cocoa cultivation; its activity, however, differed under the three soil conditions. Fluctuations in the occurrence of P. palmivora in soil did not depend on atmospheric temperature. At Obomeng, the fungus was isolated more frequently from a cocoa farm than from either an abandoned cocoa farm or a forest area. The isolation of P. palmivora from the uncultivated forest soil indicates that the fungus is indigenous to forest soils.

%B Ghana Jnl. Agric. Sci %V 7 %P 37-41 %G eng %U http://gains.org.gh/articles/gjas_v7_1_p37_41.pdf %0 Journal Article %J IMA Fungus %D 2016 %T An overview of Australia’s Phytophthora species assemblage in natural ecosystems recovered from a survey in Victoria %A William A. Dunstan %A Kay Howard %A Giles E. StJ. Hardy %A Treena I. Burgess %X

Although Phytophthora species cause serious diseases worldwide, until recently the main focus on disease in natural ecosystems in southern Australia has been on the distribution and impact of P. cinnamomi. However, new Phytophthora pathogens have emerged from natural ecosystems, and there is a need to better understand the diversity and distribution of these species in our natural forests, woodlands and heathlands. From a survey along a 70 km pipeline easement in Victoria, Phytophthora species were isolated from 249 rhizosphere samples and 25 bait bags deployed in 21 stream, river, or wetland locations. Of the 186 Phytophthora isolates recovered, 130 were identified to species based on ITS sequence data. Ninety-five isolates corresponded to 13 described Phytophthora species while additionally 35 isolates were identified as Clade 6 hybrids. Phytophthora cinnamomi was the most common species isolated (31 %), followed by P. elongata (6 %), both species were only recovered from soil. Samples from sites with the highest soil moisture at the time of sampling had the highest yield of isolates. Consistent with other studies throughout the world, Clade 6 species and their hybrids dominated water samples, although many of these species were also recovered less frequently from soil samples. Many of the species recovered in this study have not previously been reported from eastern Australia, reinforcing that Phytophthora species are widespread, abundant and diverse in natural ecosystems. We have probably been underestimating Phytophthora diversity in Australia.

%B IMA Fungus %V 7 %P 47-58 %8 Jan-01-2016 %G eng %U http://www.ingentaconnect.com/content/ima/imafung/pre-prints/content-k4_Vol7_no1_Article4 %N 1 %! imafungus %R 10.5598/imafungus.2016.07.01.04 %0 Journal Article %J Phytopathology %D 1955 %T The occurrence of Phytophthora and Pythium species on roots of native plants in northern California and southern Oregon. %A Middleton, J.T. %A Baxter, D.V. %B Phytopathology %V 45 %P 694 (abstract) %G eng %0 Journal Article %J Colombo-PR: Embrapa Florestas %D 2001 %T O complexo gomose da acácia-negra %A Santos, A. F. dos %A Grigoletti, A. Jr. %A Auer, CG %X

A acácia-negra é uma espécie florestal que foi introduzida no Brasil, no Estado do Rio Grande do Sul, na década de 30. Atualmente, com uma área plantada de aproximadamente 100.000 ha, envolve cerca de 10 mil pequenos produtores rurais (Higa & Dedecek, 1999), compondo um dos maciços florestais daquele Estado, onde desempenha importante papel sócio-econômico para as pequenas propriedades rurais (Fleig, 1993).

O rápido crescimento da acácia-negra, associado ao aproveitamento integral da madeira, torna essa espécie ideal para reflorestamento e para utilização industrial. Sua contribuição aos mais variados segmentos econômicos e industriais é ampla, tanto pelo aproveitamento da casca para extração do tanino (a casca possui cerca de 28% de tanino), quanto pelo uso da madeira para diversos fins, tais como a fabricação de papel e celulose, chapas de aglomerados, carvão e lenha. No Brasil, é plantada principalmente para produção de tanino.

A acácia-negra é uma planta que exsuda goma na casca do tronco. A goma é aparentemente produzida pelas árvores em resposta a alguma condição anormal, como patógenos ou injúrias provocadas por insetos, danos mecânicos ou fatores externos que afetam o seu crescimento (Zeijlemaker, 1968). Quimicamente, a goma da acácia-negra é uma combinação de arabinose, galactose, ramnose e ácido glucurônico (Stephen 1951). A quantidade de goma produzida por uma árvore depende da característica genética do material e da influência de fatores ambientais, tais como a temperatura e a disponibilidade de umidade.

Como resultado, tem-se pouca goma no período seco, enquanto muita goma pode ser exsudada no período úmido (Zeijlemaker, 1968). Um dos principais problemas da acácia-negra é a doença conhecida como gomose de Phytophthora sp. (Santos et al., 1998). Os sintomas ocorrem no tronco e se caracterizam por lesões necróticas na casca, chegando a atingir o lenho. A abundante exsudação gomosa é o sintoma mais característico dessa doença, que é facilmente confundido com outros problemas, uma vez que o tronco da acácia-negra exsuda goma quando lesionado por ação tanto biótica quanto abiótica. Assim sendo, embora a lesão exsudativa seja o tipo de sintoma mais característico da gomose de Phytophthora, essa não é uma característica exclusiva como indicadora da associação Phytophthora -acácia. Portanto, este trabalho tem o objetivo de discutir aspectos relacionados à gomose de Phytophthora e aos de outros tipos de problemas associados à acácia-negra e que tenham a exsudação de goma como parte de seu quadro sintomatológico, de maneira que se possam elucidá-los, para facilitar a sua identificação no camp.

%B Colombo-PR: Embrapa Florestas %V Circular Técnica, 44 %P 8 pp. %G eng %U https://core.ac.uk/download/pdf/15427678.pdf %0 Journal Article %J Forest Pathology %D 2013 %T Occurrence of Phytophthora cinnamomi in cork oak forests in Italy %A Scanu, B. %A Linaldeddu, B. T. %A Franceschini, A. %A Anselmi, N. %A A. Vannini %A A.M. Vettraino %E Belbahri, L. %X

An increasing decline and mortality of cork oak trees have been recently observed in central Italy and Sardinia Island. Following surveys conducted in three declining cork oak forests, a Phytophthora species was consistently isolated from soil samples collected from trees displaying different level of decline. Based on morphological features, growth rates at different temperatures and analysis of DNA sequences of the ITS region, all isolates were identified as Phytophthora cinnamomi Rands. This pathogen caused large brownish lesions on inoculated freshly cut branches of cork oak. It was re-isolated from all infected tissues. These findings represent the first report of P. cinnamomi on cork oak trees in Italy.

%B Forest Pathology %V 43 %P 340–343 %8 08/2013 %G eng %U http://onlinelibrary.wiley.com/doi/10.1111/efp.12039/abstract %N 4 %! For. Path. %R 10.1111/efp.12039 %0 Journal Article %J Plant Disease %D 2018 %T An Overview of Canadian Research Activities on Diseases Caused by Phytophthora ramorum: Results, Progress, and Challenges %A Shamoun, Simon Francis %A Rioux, Danny %A Callan, Brenda %A James, Delano %A Hamelin, Richard C. %A Bilodeau, Guillaume J. %A Elliott, Marianne %A Lévesque, André %A Becker, Elisa %A McKenney, Dan %A Pedlar, John %A Bailey, Karen %A Brière, S. C. %A Niquidet, Kurt %A Allen, Eric %X

International trade and travel are the driving forces behind the spread of invasive plant pathogens around the world, and human-mediated movement of plants and plant products is now generally accepted as the primary mode of their introduction, resulting in huge disturbance to ecosystems and severe socio-economic impact. These problems are exacerbated under the present conditions of rapid climatic change. We report an overview of the Canadian research activities on Phytophthora ramorum. Since the first discovery and subsequent eradication of P. ramorum on infected ornamentals in nurseries in Vancouver, British Columbia, in 2003, a research team of Canadian government scientists representing the Canadian Forest Service, Canadian Food Inspection Agency, and Agriculture and Agri-Food Canada worked together over a 10-year period and have significantly contributed to many aspects of research and risk assessment on this pathogen. The overall objectives of the Canadian research efforts were to gain a better understanding of the molecular diagnostics of P. ramorum, its biology, host-pathogen interactions, and management options. With this information, it was possible to develop pest risk assessments and evaluate the environmental and economic impact and future research needs and challenges relevant to P. ramorum and other emerging forest Phytophthora spp.

%B Plant Disease %V 102 %P 1218 - 1233 %8 Jan-07-2018 %G eng %U https://apsjournals.apsnet.org/doi/10.1094/PDIS-11-17-1730-FE %N 7 %! Plant Disease %R 10.1094/PDIS-11-17-1730-FE %0 Journal Article %J Applied and Environmental Microbiology %D 2005 %T On-Site DNA Extraction and Real-Time PCR for Detection of Phytophthora ramorum in the FieldABSTRACT %A Tomlinson, J. A. %A Boonham, N. %A Hughes, K. J. D. %A Griffin, R. L. %A Barker, I. %X

Phytophthora ramorum is a recently described pathogen causing oak mortality (sudden oak death) in forests in coastal areas of California and southern Oregon and dieback and leaf blight in a range of tree, shrub, and herbaceous species in the United States and Europe. Due to the threat posed by this organism, stringent quarantine regulations are in place, which restrict the movement of a number of hosts. Fast and accurate diagnostic tests are required in order to characterize the distribution of P. ramorum, prevent its introduction into pathogen-free areas, and minimize its spread within affected areas. However, sending samples to a laboratory for testing can cause a substantial delay between sampling and diagnosis. A rapid and simple DNA extraction method was developed for use at the point of sampling and used to extract DNAs from symptomatic foliage and stems in the field. A sensitive and specific single-round real-time PCR (TaqMan) assay for P. ramorum was performed using a portable real-time PCR platform (Cepheid SmartCycler II), and a cost-effective method for stabilizing PCR reagents was developed to allow their storage and transportation at room temperature. To our knowledge, this is the first description of a method for DNA extraction and molecular testing for a plant pathogen carried out entirely in the field, independent of any laboratory facilities.

%B Applied and Environmental Microbiology %V 71 %P 6702 - 6710 %8 Jan-11-2005 %G eng %U https://pubmed.ncbi.nlm.nih.gov/16269700/ %N 11 %! AEM %R 10.1128/AEM.71.11.6702-6710.2005 %0 Journal Article %J Forest Pathology %D 2002 %T Occurrence of Phytophthora species in oak stands in Italy and their association with declining oak trees %A A.M. Vettraino %A Barzanti, G. P. %A Bianco, M. C. %A Ragazzi, A. %A Capretti, P. %A Paoletti, E. %A Luisi, N. %A Anselmi, N. %A A. Vannini %X

Soil-borne species of Phytophthora were isolated from 19 of 30 examined oak forest areas in Italy. The frequency of isolated Phytophthora spp. (35.2%) was significantly correlated with soil pH and longitude of the sites. Eleven Phytophthora species were detected. Phytophthora cambivora, P. cinnamomi and P. cactorum were recovered from sites in central and southern Italy whereas P. quercina was isolated in the northern and central part of the country. Phytophthora citricola occurred all over Italy. Phytophthora quercina was the only species significantly associated with declining oak trees.

%B Forest Pathology %I Blackwell Science Ltd. %V 32 %P 19–28 %G eng %U http://dx.doi.org/10.1046/j.1439-0329.2002.00264.x %R 10.1046/j.1439-0329.2002.00264.x %0 Journal Article %J European Journal of Plant Pathology %D 2005 %T Occurrence and distribution of Phytophthora; species in European chestnut stands, and their association with Ink Disease and crown decline %A Vettraino, A. %A Morel, O. %A Perlerou, C. %A Robin, C. %A Diamandis, S. %A A. Vannini %X

The Phytophthora complex associated with Castanea sativa Mill. was investigated in five European countries in 35 regions and with respect to various domestication levels. Annual precipitation and length of drought season were the main parameters that regulated the presence of Phytophthora species in the chestnut stands. Seven species of Phytophthora were detected; three of these, P. megasperma, P. cryptogea and P. syringae had not been previously reported on sweet chestnut. P. cinnamomi. P. cambivora and P. citricola were most frequently isolated. P. cinnamomi and P. cambivora were the species significantly associated with declining trees with symptoms of Ink Disease. P. cinnamomi required distinct ecological conditions compared to the other species. P. cinnamomi was never detected in sites characterized by minimum temperatures below 1.4 °C, maximum temperature above 28 °C, or soil pH below 5.4. The results obtained provide useful information for modeling the probability of Ink Disease, crown decline and associated Phytophthora species in chestnut groves in global climatic change scenarios.

%B European Journal of Plant Pathology %I Springer Netherlands %V 111 %P 169-180 %G eng %U http://dx.doi.org/10.1007/s10658-004-1882-0 %0 Journal Article %J Fungal Biology %D 2010 %T Oospores progenies from Phytophthora ramorum %A Boutet Xavier %A Vercauteren Annelies %A Heungens Kurt %A Laurent Fréderic %A Chandelier Anne %K Sexual reproduction %X

Oospores of Phytophthora ramorum were produced from intraspecific pairings between a European A1 and European or American A2 strains. Their viability was evaluated through colouration with tetrazolium bromide. The distribution of oospores in the different classes of colouration was similar to that found in other Phytophthora species (homothallic and heterothallic): most of the oospores stained purple, which corresponds to spores in dormancy. In order to produce single-oospore cultures, a method was developed to separate oospores from mycelium and chlamydospores. Germination of oospores was observed in 110, 250, 350 and 500-d-old cultures at a low proportion. Microsatellite marker analyses on oospore progenies revealed that the oospores resulted from hybridisation. More than 50 oospore progenies were characterised in terms of mating type, aggressiveness on Rhododendron leaves, and growth rate on two different media. The results are discussed in the context of pest risk analysis.

%B Fungal Biology %V 114 %P 369 - 378 %G eng %U http://www.sciencedirect.com/science/article/pii/S1878614610000383 %R 10.1016/j.funbio.2010.02.009