%0 Journal Article %J Plant Disease %D 2008 %T First report of chestnut ink disease by Phytophthora katsurae on chestnut in Korea %A E. Oh %A Lee, S. H. %A Kim, K. H. %A Lee, J. K. %A Shin, K. C. %B Plant Disease %V 92 %P p. 312 %G eng %U http://apsjournals.apsnet.org/doi/abs/10.1094/PDIS-92-2-0312A %R 10.1094/PDIS-92-2-0312A %0 Journal Article %J IMA Fungus %D 2013 %T Surveys of soil and water reveal a goldmine of Phytophthora diversity in South African natural ecosystems %A Oh, Eunsung %A Gryzenhout, Marieka %A Wingfield, Brenda D. %A Wingfield, Michael J. %A Burgess, Treena I. %X

Phytophthora species are well-known as destructive plant pathogens, especially in natural ecosystems. It is ironic, therefore, how little is known regarding the Phytophthora diversity in South African natural woody ecosystems. In this study, Phytophthora species were isolated using standard baiting techniques from 182 soil and water samples and these were identified based on ITS and coxI sequence data. The 171 resulting Phytophthora isolates resided in 14 taxa including six known species (P. multivora, P. capensis, P. cryptogea, P. frigida, P. cinnamomi, P. cinnamomi var. parvispora), the known but as yet unnamed Phytophthora sp. PgChlamydo, P. sp. emzansi, and P. sp. Kununurra and five novel taxa referred to as P. sp. stellaris, P. sp. Umtamvuna P. sp. canthium, P. sp. xWS, P. sp. xHennops. Four of the new taxa were found exclusively in water and two of these are hybrids. The most commonly isolated species from soil was P. multivora, a species recently described from Western Australia. Phytophthora frigida was isolated for the first time from stream water. With the exception of P. cinnamomi, very little is known regarding the biology, epidemiology or origin of Phytophthora in South Africa.

%B IMA Fungus %V 4 %P 123 - 131 %8 Jun-06-2015 %G eng %U http://www.imafungus.org/Issue/41/22.pdf %N 1 %! imafungus %R 10.5598/imafungus.2013.04.01.12 %0 Thesis %D 2004 %T Resistance mechanisms of Port-Orford-cedar to Phytophthora lateralis %A Oh, Eunsung %I Oregon State University %C Corvallis %G eng %9 masters %0 Journal Article %J Forest pathology %D 2006 %T Port-Orford-cedar resistant to Phytophthora lateralis. %A E. Oh %A R. A. Sniezko %A Hansen, E.M. %B Forest pathology %V 36 %P 385–394 %G eng %U http://onlinelibrary.wiley.com/doi/10.1111/j.1439-0329.2006.00474.x/full %R 10.1111/j.1439-0329.2006.00474.x %0 Journal Article %J Phytopathology %D 2007 %T Histopathology of infection and colonization of susceptible and resistant Port-Orford-cedar by Phytophthora lateralis. %A E. Oh %A Hansen, E.M. %K Chamaecyparis lawsoniana %K developmental stages %K forest trees %K fungal anatomy %K fungal diseases of plants %K histopathology %K infection %K North America %K ornamental plants %K pathogenicity %K Phytophthora lateralis %K plant morphology %K plant pathogenic fungi %K roots %K signs and symptoms (plants) %K stems %B Phytopathology %V 97 %P 684–693 %G eng %U http://apsjournals.apsnet.org/doi/abs/10.1094/PHYTO-97-6-0684 %R http://dx.doi.org/10.1094/PHYTO-97-6-0684 %0 Journal Article %J European Journal of Plant Pathology %D 2007 %T Assessment of sanitation and fungicide application directed at cocoa tree trunks for the control of Phytophthora black pod infections in pods growing in the canopy %A Opoku, Isaac Y. %A Akrofi, Andrews Y. %A Appiah, Alex A. %X

Studies were conducted in two cocoa-growing areas of Ghana, one solely affected by Phytophthora palmivora and the other predominantly by Phytophthora megakarya, to determine the effectiveness of sanitation practices and fungicide application on tree trunks for the control of black pod disease in the canopy. Sanitation practices including weeding, pruning, thinning, shade reduction and removal of mummified pods were carried out prior to fungicide applications, and diseased pods were routinely removed at monthly intervals during harvesting. Three types of fungicides were used: systemic (Foli-R-Fos 400) applied as injection into the main trunks, semi-systemic (Ridomil 72 plus) and contact (Nordox 75, Kocide 101, Kocide DF, Blue Shield and Funguran-OH) applied as sprays onto pods on the main trunk. Sanitation combined with fungicide application on the trunk significantly reduced black pod disease incidence in the tree canopy. For fungicides applied as a spray, Ridomil 72 plus at 3.3 g l−1 and Kocide DF at 10 g l−1 and as injection, 40 ml Foli-R-Fos 400 injected twice a year, performed better than the other fungicide treatments. The position of pods significantly influenced the incidence of canopy black pod infection in the P. megakarya predominantly affected area but to a lesser extent in the P. palmivora solely affected area. However, no significant interactions were found between fungicide treatments and the position of pods on the tree in both disease areas. The determined trunk-canopy relationship in the development of black pod disease on cocoa can be used in disease control programmes to maximise the impact of sanitation practices, achieve judicious application of fungicides, thereby reducing the environmental impact of fungicides on the cocoa ecosystem, and ultimately increase the economic returns.

%B European Journal of Plant Pathology %V 117 %P 167 - 175 %8 1/2007 %G eng %U http://link.springer.com/article/10.1007%2Fs10658-006-9082-8 %N 2 %! Eur J Plant Pathol %R 10.1007/s10658-006-9082-8 %0 Journal Article %J African Journal of Agricultural Research %D 2007 %T Management of black pod disease of cocoa with reduced number of fungicide application and crop sanitation %A OpokuI, Y %A Assuah, MK %A Aneani, F %X

Black pod disease caused by Phytophthora megakarya is the most important fungal disease on cocoa in Ghana. The current recommended control method of combining sanitation practices with 6 - 8 fungicide applications in a year is considered unfriendly to the environment, too expensive and time consuming. Consequently, fungicide adoption rate by farmers is extremely low. Studies were therefore conducted to determine the effectiveness of combining 1 - 3 fungicide application in June and/or September/October with crop sanitation for the control of cocoa black pod disease caused by P. megakarya. Sanitation practices were common to all the treatments and the fungicide application(s) superimposed. A semi-systemic fungicide, Ridomil 72 plus (12% metalaxyl + 60% copper-1-oxide), was used as the test fungicide. Fungicide application combined with crop sanitation practices were effective in the management of the severe form of black pod disease caused by P. megakarya, resulting in 25% to 48% disease reduction and 10.9% to 51.8% yield increase. Combining the sanitation practices with three fungicide applications gave significantly better results, in terms of disease control and yields than either sanitation practices alone or combining them with one or two fungicide applications. However, the combination of sanitation practices and three fungicide applications was significantly less effective than the standard fungicide application of six times a year. All the fungicide applications and/or crop sanitation practices were profitable with a Benefit Cost Ratio (BCR) ranging from 1.8 - 2.1.

%B African Journal of Agricultural Research %V 2 %P 601–604 %G eng %U http://www.academicjournals.org/article/article1380898856_Opoku%20et%20al.pdf %N 11 %0 Journal Article %J Forest Pathology %D 2011 %T Phytophthora root and collar rot of mature Fraxinus excelsior in forest stands in Poland and Denmark %A Orlikowski, L.B. %A Ptaszek, M. %A Rodziewicz, A. %A Nechwatal, J. %A Thinggaard, K. %A T. Jung %X

In recent years, Common ash (Fraxinus excelsior) throughout Europe has been severely impacted by a leaf and twig dieback caused by the hyphomycete Chalara fraxinea. The reasons for its current devastating outbreak, however, still remain unclear. Here, we report the presence of four Phytophthora taxa in declining ash stands in Poland and Denmark. Phytophthora cactorum, Phytophthora plurivora, Phytophthora taxon salixsoil and Phytophthora gonapodyides were isolated from rhizosphere soil samples and necrotic bark lesions on stems and roots of mature declining ash trees in four stands. The first three species proved to be aggressive to abscised roots, twigs and leaves of F. excelsior in inoculation experiments. Soil infestation tests also confirmed their pathogenicity towards fine and feeder roots of ash seedlings. Our results provide first evidence for an involvement of Phytophthora species as a contributing factor in current decline phenomena of F. excelsior across Europe. Specifically, they may act as a predisposing factor for trees subsequently infected by C. fraxinea. Phytophthora species from ash stands also proved to be aggressive towards a wide range of tree and shrub species commonly associated with F. excelsior in mixed stands. Although damage varied considerably depending on the Phytophthora species/isolate-host plant combination, these results show that many woody species may be a potential source for survival and inoculum build-up of soilborne Phytophthora spp. in ash stands and forest ecosystems in general.

%B Forest Pathology %I Blackwell Publishing Ltd %V 41 %P 510–519 %G eng %U http://dx.doi.org/10.1111/j.1439-0329.2011.00714.x %R 10.1111/j.1439-0329.2011.00714.x %0 Journal Article %J Phytopatologia Polonica %D 2006 %T First record on Phytophthora spp. associated with the decline of European beech stand in south-west Poland %A Orlikowski, L.B. %A Oszako, T. %A Szkuta, G %K Beech %K bleeding canker %K pathogenicity %K root rot %K soil %X

Phytophthora citricola was detected in Siewierz Forest District in soil samples and diseased bark taken from declined 88-111-year-old European beech trees growing in three compartments of Trzebyczka Forest. Phytophthora cambivora was isolated only from diseased fine roots, bleeding cankers near trunk base and aerial canker spots. Both species colonised leaves and young stem parts as well as five-year-old beech branches. Necrosis spread about 1 mm/24 h.

%B Phytopatologia Polonica %V 42 %P 37-46 %G eng %0 Journal Article %J Plant Health Progress %D 2004 %T Surveying for and eradicating Phytophthora ramorum in agricultural commodities %A Osterbauer, N. K. %A Griesbach, J. A. %A Hedberg, J. %X

Since 2001, Oregon nurseries, Christmas tree plantations, and other sites have been surveyed for the federally regulated pathogen Phytophthora ramorum. Host plants at each site were visually surveyed for disease symptoms and symptomatic tissues tested in the laboratory by isolation onto a selective medium and by a polymerase chain reaction (PCR) assay. In 2002 and 2003, we detected PCR-positive plants that later proved to be infected with another Phytophthora, suggesting there are limitations to the PCR assay tested. In 2003, P. ramorum was detected for the first time in Viburnum, Pieris, Rhododendron, and Camellia plants in six nurseries. All infected and neighboring plant materials were destroyed by incineration and the nurseries and surrounding environs subsequently surveyed for the pathogen. Phytophthora ramorum was not detected, indicating the pathogen was successfully eradicated.

%B Plant Health Progress %G eng %R doi:10.1094/PHP-2004-0309-02-RS %0 Journal Article %J Phytopathology %D 1977 %T Detection of Phytophthora lateralis in soil organic matter and factors that affect its survival. %A W.D. Ostrofsky %A L.F. Roth %A R.G. Pratt %K Chamaecyparis lawsoniana %B Phytopathology %V 67 %P 79–84 %G eng %0 Journal Article %J Journal of Forest Science %D 2001 %T Significance of Phytophthoras and Pythium for oak, alder and spruce decline. %A W. Oßwald %A T. Jung %A Nechwatal, J. %A Schlenzig, A. %A F. Fleischmann %X

The results of a survey of soil borne Phytophthoras in 35 oak (Quercus) stands on geologically different sites in Bavaria clearly showed that the most widespread species were identified as Phytophthora citricola, P. cambivora and P. quercina. These three species were only isolated from rhizosphere soil of stands with mean soil pH-values (CaCl2) of 3.5 and higher on loamy, clayey or sandy-loamy soil texture. At these Phytophthora stands, all root parameters of declining oaks were significantly reduced as compared to healthy looking trees. It is concluded that the above mentioned Phytophthora species are involved in oak decline as primary root rot pathogens on clay or sandy-loamy stands with soil pH-values higher than 3.5. A new Phytophthora hybrid, called 'alder Phytophthora', was isolated frequently from bark sections of declining alders along several Bavarian rivers and from nursery plants. PCR-RFLP analysis proved that the Bavarian isolates belonged to the same hybrid variants found in Great Britain, Sweden, France or Denmark. Spruce decline was studied in the Bavarian Alps on stands representing various site conditions. Most root parameters were negatively correlated with crown transparency. In addition, the total number of lateral roots was significantly lower for declining compared to healthy trees. Remarkably, only Pythium species were isolated from rhizosphere soil, which were divided into several groups after PCR-RFLP analysis. In soil infestation tests, most of the isolates caused severe root damage on spruce similar to root rot seen on declining trees in the field.

%B Journal of Forest Science %V 47 %P 96-103 %G eng %N Special Issue %9 Journal article; Conference paper %0 Journal Article %J Forest Pathology %D 2014 %T Strategies of attack and defence in woody plant- Phytophthora interactions %A Oßwald, W. %A Fleischmann, F. %A Rigling, D. %A Coelho, A. C. %A Cravador, A. %A Diez, J. %A Dalio, R. J. %A Horta Jung, M. %A Pfanz, H. %A Robin, C. %A Sipos, G. %A Solla, A. %A Cech, T. %A Chambery, A. %A Diamandis, S. %A Hansen, E. %A Jung, T. %A Orlikowski, L. B. %A Parke, J. %A Prospero, S. %A Werres, S. %X

This review comprises both well-known and recently described Phytophthora species and concentrates on Phytophthora–woody plant interactions. First, comprehensive data on infection strategies are presented which were the basis for three models that explain invasion and spread of Phytophthora pathogens in different woody host plants. The first model describes infection of roots, the second concentrates on invasion of the trunk, and the last one summarizes infection and invasion of host plants via leaves. On the basis of morphological, physiological, biochemical and molecular data, scenarios are suggested which explain the sequences of reactions that occur in susceptible and tolerant plants following infections of roots or of stem bark. Particular emphasis is paid to the significance of Phytophthora elicitins for such host–pathogen interactions. The overall goal is to shed light on the sequences of pathogenesis to better understand how Phytophthora pathogens harm their host plants.

%B Forest Pathology %V 44 %P 169–190 %8 June 2014 %G eng %U http://doi.wiley.com/10.1111/efp.12096 %N 3 %! For. Path. %R 10.1111/efp.12096 %0 Journal Article %J Mycological Research %D 1991 %T A revised systematics of twelve papillate Phytophthora species based on isozyme analysis %A Oudemans, Peter %A Coffey, Michael D. %X

Isoenzyme analysis was used to examine intraspecific diversity and interspecific relatedness of P. cactorum (group I) and 12 papillate species of Phytophthora within group II of Waterhouse's (1963) taxonomic scheme. Isolates of 6 species, specifically P. botryosa, P. heveae, P. katsurae, P. meadii, P. palmivora and P. parasitica (P. nicotianae var. parasitica), contained low levels of genetic diversity and were judged to be valid species. Based upon isoenzyme analysis, all isolates of P. arecae were found to be identical with some isolates of P. palmivora. Thus, it is proposed that these 2 species are synonymous. For P. nicotianae var. parasitica, differences in oospore size or host plant were contrasted with the isoenzyme data using single locus coefficients and no evidence was found to support the existence of distinct varieties. In contrast, several other species, particularly P. capsici, P. citrophthora and P. megakarya, demonstrated much higher levels of variation in isoenzyme pattern and subgroups were readily identified. Isolates of P. capsici, including those previously identified as P. palmivora 'MF4' separated into 3 subgroups CAP1, CAP2 and CAP3. Those in CAP1 were from widely distributed geographical locations on a range of hosts including Capsicum sp., tomato, cucurbits, as well as cocoa and black pepper and it contained the greatest amount of intraspecific diversity. A single representative of P. mexicana also clustered with this subgroup and as such is considered conspecific to P. capsici. CAP2 isolates were found primarily on black pepper and from Hawaii on Macadamia integrifolia as well as other hosts. In some instances, specifically with isolates from India and Indonesia on black pepper both CAP1 and CAP2 were found. However, the evidence from isoenzymes suggests that the 2 groups are genetically isolated from one another. All representatives of CAP3 were derived from diseased cocoa in Brazil and this subgroup was monomorphic for all loci examined. P. citrophthora was divided into 2 subgroups. Isolates of CTR1 were derived from a large range of hosts including citrus and kiwi fruit. CTR2 was composed of only Brazilian isolates from cocoa. P. megakarya, which has only been reported on cocoa from West Africa, was also divided into 2 subgroups which were separated geographically. Isolates of MGK1 originated from either Nigeria or Guinea and isolates of MGK2 were from Cameroon. P. boehmeriae was the most genetically diverse species examined with 4 isoenzymatically diverse ETs representing only 11 isolates. Interspecific comparisons revealed relationships which would not have been predicted based on morphological comparisons alone. For example, P. meadii and P. botryosa clustered together indicating a very close genetic relatedness. P. katsurae and P. heveae also formed a single cluster. However, comparison of oospores of these 2 species showed that the oogonial stalk length of P. katsurae was consistently much longer. Unexpectedly, P. capsici and P. citrophthora also formed a cluster indicating that they were genetically related. Finally, the results of this isoenzyme analysis suggest that the papillate species of Group II of Waterhouse's (1963) scheme may form at least 6 distinct evolutionary lines.

%B Mycological Research %V 95 %P 1025 - 1046 %8 Jan-09-1991 %G eng %U http://linkinghub.elsevier.com/retrieve/pii/S0953756209805431 %N 9 %! Mycological Research %R 10.1016/S0953-7562(09)80543-1