Articles de revues : « Phytophthora sp »

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Man in 't Veld, Willem A., Wil J. Veenbaas-Rijks, Elena Ilieva, Arthur W. A. M. de Cock, Peter J. M. Bonants et Rob Pieters. « Natural Hybrids of Phytophthora nicotianae and Phytophthora cactorum Demonstrated by Isozyme Analysis and Random Amplified Polymorphic DNA ». Phytopathology® 88, n^o 9 (septembre 1998) : 922–29. http://dx.doi.org/10.1094/phyto.1998.88.9.922.

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Three similar isolates of Phytophthora (Phytophthora sp-h) were obtained from diseased Spathiphyllum and Primula plants. Cultural characteristics did not fit any known description of Phytophthora species. The Phytophthora sp-h isolates are papillate, are homothallic, possess 80 to 86% amphigynous antheridia, and have a maximum temperature for growth of 36.5°C. Isozyme analysis of the Phytophthora sp-h isolates revealed a three-banded pattern with malic enzyme and a three-banded pattern with malate dehydrogenase on the second putative locus. The fastest band at both enzyme loci comigrated with the single P. nicotianae band, the slowest band comigrated with the single P. cactorum (and also P. pseudotsugae) band, and one band in between was concluded to represent the heterodimeric isozyme. The random amplified polymorphic DNA patterns of the Phytophthora sp-h isolates almost exclusively consisted of bands that were also present in either P. nicotianae or P. cactorum. Southern hybridization showed that bands specific for P. nicotianae were present as comigrating bands in the Phytophthora sp-h isolates. The same was found for species-specific bands of P. cactorum. It is concluded that the three Phytophthora sp-h isolates represent interspecific hybrids, P. nicotianae being the one parent and P. cactorum the other. Analysis of mito-chondrial DNA with restriction enzymes revealed banding patterns in all the Phytophthora sp-h isolates identical with those of P. nicotianae, confirming that indeed P. nicotianae was one of the parents.

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Dwiastuti, Mutia Erti, Sri Widyaningsih, Rudi Cahyo Wicaksono, Dina Agustina et Unun Triasih. « IDENTIFICATION OF VESICULAR ARBUSCULAR MYCORRHIZA (VAM) FROM SOIL AND ITS POTENCY IN REDUCING DISEASE DEVELOPMENT (Phytophthora sp.) ON 5 CITRUS ROOTSTOCK ». El-Hayah 7, n^o 2 (27 mars 2019) : 74–83. http://dx.doi.org/10.18860/elha.v7i2.8426.

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Phytophthora spp. is one of the fungal pathogens that kills plants on several kinds of the citrus rootstock. In other countries, it is reported that disease pathogens were reduced in roots containing Vesicular Arbuscular Mycorrhiza (VAM interaction). However, in Indonesia, there is less information about the effect of VAM on the roots of citrus plants against root disease caused by Phytophthora sp. This study aimed to identify VAM in citrus roots and study the potential of VAM in controlling root rot of Phytophthora sp. on five types of the citrus rootstock. The research was carried out at the Phytopathology Laboratory, Indonesian Citrus, and Subtropical Fruits Research Institute (ICSFRI). Phytophthora spp. and VAM samples originated from several citrus centers endemic to Phytophthora were collected. VAM was isolated from the rhizosphere area of citrus plants, while Phytophthora sp. was isolated from infected plant roots. The fungus isolates were isolated, purified, then identified through references. The test of the potential of VAM in increasing resistance of root diseases caused by Phytophthora sp. was performed at the screen house in ICSFRI. The results of the study showed that VAM was identified in 39 gardens in 6 districts from samples collected in 49 yards in 10 regions of citrus centers. The dominant VAM genus is Glomus sp. with the highest density of spores was originated from Ponorogo area. The results of the identification of Phytophthora morphologically showed a diversity of Phytophthora, namely P. parasitica, P. palmivora, and P. citrophthora. The test of the potential of VAM in increasing plant resistance to Phytophthora results showed that Kanci, JC, RL, and Volkameriana varieties inoculated with Phytophthora sp. and Glomus sp. have higher plant height than healthy plants.

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La Spada, Federico, Peter J. A. Cock, Eva Randall, Antonella Pane, David E. L. Cooke et Santa Olga Cacciola. « DNA Metabarcoding and Isolation by Baiting Complement Each Other in Revealing Phytophthora Diversity in Anthropized and Natural Ecosystems ». Journal of Fungi 8, n^o 4 (22 mars 2022) : 330. http://dx.doi.org/10.3390/jof8040330.

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Isolation techniques supplemented by sequencing of DNA from axenic cultures have provided a robust methodology for the study of Phytophthora communities in agricultural and natural ecosystems. Recently, metabarcoding approaches have emerged as new paradigms for the detection of Phytophthora species in environmental samples. In this study, Illumina DNA metabarcoding and a conventional leaf baiting isolation technique were compared to unravel the variability of Phytophthora communities in different environments. Overall, 39 rhizosphere soil samples from a natural, a semi-natural and a horticultural small-scale ecosystem, respectively, were processed by both baiting and metabarcoding. Using both detection techniques, 28 out of 39 samples tested positive for Phytophthora. Overall, 1,406,613 Phytophthora internal transcribed spacer 1 (ITS1) sequences and 155 Phytophthora isolates were obtained, which grouped into 21 taxa, five retrieved exclusively by baiting (P. bilorbang; P. cryptogea; P. gonapodyides; P. parvispora and P. pseudocryptogea), 12 exclusively by metabarcoding (P. asparagi; P. occultans; P. psycrophila; P. syringae; P. aleatoria/P. cactorum; P. castanetorum/P. quercina; P. iranica-like; P. unknown sp. 1; P. unknown sp. 2; P. unknown sp. 3; P. unknown sp. 4; P. unknown sp. 5) and four with both techniques (P. citrophthora, P. multivora, P. nicotianae and P. plurivora). Both techniques complemented each other in describing the variability of Phytophthora communities from natural and managed ecosystems and revealing the presence of rare or undescribed Phytophthora taxa.

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Kondo, Toru, Kayoko Otsubo et Koji Kageyama. « Phytophthora rot of alpine delphinium caused by Phytophthora sp. kelmania ». Journal of General Plant Pathology 88, n^o 2 (15 janvier 2022) : 145–49. http://dx.doi.org/10.1007/s10327-021-01050-5.

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Muzuni, Muzuni, Haidin Haidin et Nur Arfa Yanti. « Karakterisasi Morfologi Phytophthora sp. Asal Buah Kakao Desa Olo-oloho, Kabupaten Konawe, Sulawesi Tenggara ». BioWallacea : Jurnal Penelitian Biologi (Journal of Biological Research) 7, n^o 1 (5 mai 2020) : 1064. http://dx.doi.org/10.33772/biowallacea.v7i1.11812.

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This study aimed to determine the morphological characteristics of Phytophthora sp. isolated from cocoa fruits from Olo-oloho Village, Konawe Regency, Southeast Sulawesi. Isolation of Phytophthora sp. carried out by the point method using V4 (Vegetable Juice Agar) media incubated at 27ºC for 24 hours. Morphological characterization of Phytophthora sp. included characterization of colony morphology and cell morphology. The results showed that the colony morphological characteristics were white colonies, cotton-like textures, the uneven edge of the colony, zoning and radial lines. The morphological characteristics of the cell had asexual spores in the form of sporangium and chlamydospores, hyphae are not aseptic, greenish-black zoospores, zoospores are round and double-flagged, and have sporangiophores. Keywords: Phytophthora sp., colony morphology, cell morphology

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Balci, Y., S. Balci, J. Eggers, W. L. MacDonald, J. Juzwik, R. P. Long et K. W. Gottschalk. « Phytophthora spp. Associated with Forest Soils in Eastern and North-Central U.S. Oak Ecosystems ». Plant Disease 91, n^o 6 (juin 2007) : 705–10. http://dx.doi.org/10.1094/pdis-91-6-0705.

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A survey of soils associated with oak species was conducted in 2003 and 2004 in Indiana, Illinois, Maryland, Michigan, Minnesota, Pennsylvania, Ohio, West Virginia, and Wisconsin to investigate the occurrence of Phytophthora spp. Soils taken from around the base of healthy and declining oak trees were flooded with H2O and Quercus robur leaflets were used as bait for Phytophthora spp. From 829 soil samples collected near trees, 21% were positive for Phytophthora spp., with 55% of the 125 sites surveyed yielding a Phytophthora sp. Phytophthora cinnamomi was the most frequently isolated species, representing 69.4% of the Phytophthora-infested sites surveyed. Other species, in decreasing order of isolation frequency were Phytophthora sp. 2, P. citricola, P. europaea, P. cambivora, P. quercina-like isolates, and Phytophthora sp. 1. No significant association was found between the presence of Phytophthora organisms and site characteristics such as latitude, elevation, soil pH, or the crown condition of the trees. However, in P. cinnamomi-infested sites, a significant association was found with the deteriorating crown status of Q. alba and the presence of P. cinnamomi. The absence of P. cinnamomi above the 40°N latitude range also was noteworthy.

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Jung, Thomas, Bruno Scanu, Clive Brasier, Joan Webber, Ivan Milenković, Tamara Corcobado, Michal Tomšovský et al. « A Survey in Natural Forest Ecosystems of Vietnam Reveals High Diversity of both New and Described Phytophthora Taxa including P. ramorum ». Forests 11, n^o 1 (12 janvier 2020) : 93. http://dx.doi.org/10.3390/f11010093.

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In 2016 and 2017, surveys of Phytophthora diversity were performed in 25 natural and semi-natural forest stands and 16 rivers in temperate and subtropical montane and tropical lowland regions of Vietnam. Using baiting assays from soil samples and rivers and direct isolations from naturally fallen leaves, 13 described species, five informally designated taxa and 21 previously unknown taxa of Phytophthora were isolated from 58 of the 91 soil samples (63.7%) taken from the rhizosphere of 52 of the 64 woody plant species sampled (81.3%) in 20 forest stands (83.7%), and from all rivers: P. capensis, P. citricola VII, VIII, IX, X and XI, P. sp. botryosa-like 2, P. sp. meadii-like 1 and 2, P. sp. tropicalis-like 2 and P. sp. multivesiculata-like 1 from Phytophthora major phylogenetic Clade 2; P. castaneae and P. heveae from Clade 5; P. chlamydospora, P. gregata, P. sp. bitahaiensis-like and P. sp. sylvatica-like 1, 2 and 3 from Clade 6; P. cinnamomi (Pc), P. parvispora, P. attenuata, P. sp. attenuata-like 1, 2 and 3 and P. ×heterohybrida from Clade 7; P. drechsleri, P. pseudocryptogea, P. ramorum (Pr) and P. sp. kelmania from Clade 8, P. macrochlamydospora, P. sp. ×insolita-like, P. sp. ×kunnunara-like, P. sp. ×virginiana-like s.l. and three new taxa, P. sp. quininea-like, P. sp. ×Grenada 3-like and P. sp. ×Peru 4-like, from Clade 9; and P. sp. gallica-like 1 and 2 from Clade 10. The A1 and A2 mating types of both Pc and Pr co-occurred. The A2 mating type of Pc was associated with severe dieback of montane forests in northern Vietnam. Most other Phytophthora species, including Pr, were not associated with obvious disease symptoms. It is concluded that (1) Vietnam is within the center of origin of most Phytophthora taxa found including Pc and Pr, and (2) Phytophthora clades 2, 5, 6, 7, 8, 9, and 10 are native to Indochina.

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Saude, C., O. P. Hurtado-Gonzales, K. H. Lamour et M. K. Hausbeck. « Occurrence and Characterization of a Phytophthora sp. Pathogenic to Asparagus (Asparagus officinalis) in Michigan ». Phytopathology® 98, n^o 10 (octobre 2008) : 1075–83. http://dx.doi.org/10.1094/phyto-98-10-1075.

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A homothallic Phytophthora sp. was recovered from asparagus (Asparagus officinalis) spears, storage roots, crowns, and stems in northwest and central Michigan in 2004 and 2005. Isolates (n = 131) produced ovoid, nonpapillate, noncaducous sporangia 45 μm long × 26 μm wide and amphigynous oospores of 25 to 30 μm diameter. Mycelial growth was optimum at 25°C with no growth at 5 and 30°C. All isolates were sensitive to 100 ppm mefenoxam. Pathogenicity studies confirmed the ability of the isolates to infect asparagus as well as cucurbits. Amplified fragment length polymorphism analysis of 99 isolates revealed identical fingerprints, with 12 clearly resolved fragments present and no clearly resolved polymorphic fragments, suggesting a single clonal lineage. The internal transcribed spacer regions of representative isolates were homologous with a Phytophthora sp. isolated from diseased asparagus in France and a Phytophthora sp. from agave in Australia. Phylogenetic analysis supports the conclusion that the Phytophthora sp. isolated from asparagus in Michigan is a distinct species, and has been named Phytophthora asparagi.

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Martin, Deva Aziz Nanda, et Ali Rahmat. « Relationship of Soil Physicochemical Properties and Existence of Phytophthora sp. in Pineapple Plantations ». Indonesian Journal of Science and Technology 2, n^o 1 (1 avril 2017) : 81. http://dx.doi.org/10.17509/ijost.v2i1.5991.

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One of the tropical fruits with high economic value is pineapple. Pineapple plantation has several limitations, especially in cultivating period and diseases caused by Phytophthora sp. (called heart rot disease). The spread of Phytophthora sp. in pineapple plantation is influenced by physical of soil (called as soil borne pathogen). Here, the purpose of this study was to examine physical properties of soil (compaction), specifically on heart rot disease in pineapple plantation. We used pineaple farm locating in Central Lampung, Indonesia. In this paper, we analyzed the disease impact from the soil compaction point of view. We investigated the difference between soil samples with and without sick plant. The results showed that the disease area were affected by Phytophthora sp. area have high soil compaction. Indeed, this soil condition is good for growing Phytophthora sp.

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Schwingle, B. W., et R. A. Blanchette. « Host Range Investigations of New, Undescribed, and Common Phytophthora spp. Isolated from Ornamental Nurseries in Minnesota ». Plant Disease 92, n^o 4 (avril 2008) : 642–47. http://dx.doi.org/10.1094/pdis-92-4-0642.

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Eleven woody landscape plants commonly grown in the upper Midwestern United States were inoculated with up to three unnamed Phytophthora taxa (Phytophthora taxon Pgchlamydo, a Phytophthora alni-like isolate [Phytophthora MN14d], and Phytophthora sp. MN1) to explore their host ranges. In addition, P. cactorum, P. citricola, P. citrophthora, P. hedraiandra, and P. nicotianae were used to inoculate plants to further investigate the susceptibilities of plant genera previously found associated with these pathogens, to explore the susceptibility of important landscape plants (i.e., oak) to common ornamental Phytophthora spp., and to prove Koch's postulates. Koch's postulates were completed on fragrant sumac with P. citricola and P. nicotianae and on common lilac with P. citrophthora. A nonwound or wound inoculation technique were used to determine host susceptibility. Phytophthora sp. MN1 caused symptoms on American cranberrybush, bur and red oak, common lilac, fragrant sumac, Norway maple, and ‘P.J.M.’ rhododendron. The newly described organism P. hedraiandra caused disease on American cranberrybush, common lilac, red oak, and ‘Snowdrift’ crabapple. Fragrant sumac and common lilac generally were the most susceptible hosts to all Phytophthora spp. This study demonstrated that many ornamental Phytophthora pathogens have larger potential host ranges than previously known. The biology and ecology of P. hedraiandra and Phytophthora sp. MN1 must be further investigated, and methods for rapid identification should be developed.

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Lee, Gun-Joo, Joon-Hee Han, Jong-Hwan Shin, Heung Tae Kim et Kyoung Su Kim. « Antifungal Activity of Bacillus sp. GJ-1 Against Phytophthora capsici ». Korean Journal of Mycology 41, n^o 2 (30 juin 2013) : 112–17. http://dx.doi.org/10.4489/kjm.2013.41.2.112.

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Man in ’t Veld, Willem A., Karin C. H. M. Rosendahl, Patricia C. J. van Rijswick, Johan P. Meffert, Marcel Westenberg, Bart T. L. H. van de Vossenberg, Geoff Denton et Fons A. J. van Kuik. « Phytophthora terminalis sp. nov. and Phytophthora occultans sp. nov., two invasive pathogens of ornamental plants in Europe ». Mycologia 107, n^o 1 (janvier 2015) : 54–65. http://dx.doi.org/10.3852/12-371.

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Rutherford, F. S., et E. W. B. Ward. « Estimation of relative DNA content in nuclei of races of Phytophthora megasperma f. sp. glycinea by quantitative fluorescence microscopy ». Canadian Journal of Genetics and Cytology 27, n^o 5 (1 octobre 1985) : 614–16. http://dx.doi.org/10.1139/g85-091.

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The fluorochrome 4,6-diamidino-2-phenylindole was used as a stain for nuclear DNA in the fungus Phytophthora megasperma f. sp. glycinea. Measurements of DNA contents were made cytofluorometrically using known haploid and diploid strains of Aspergillus nidulans as standards. No significant differences between DNA levels in nine races of Phytophthora megasperma f. sp. glycinea were found. The results are consistent with genetical data that all nine races are diploid in the vegetative state.Key words: Phytophthora, ploidy, fungi, DNA content, fluorescence.

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Akıllı Şimşek, Seçil, Yakup Zekai Katırcıoğlu et Salih Maden. « Türkiye’de Orman, Park ve Fidanlıklarda Görülen Phytophthora Kök Çürüklüğü Hastalıkları ve Korunma Önlemleri ». Turkish Journal of Agriculture - Food Science and Technology 6, n^o 6 (26 juin 2018) : 770. http://dx.doi.org/10.24925/turjaf.v6i6.770-782.1928.

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Phytophthora species, as a member of Oomycetes are important plan diseases occurring on almost all of the annual and perennial plants and rapidly killing the plants by producing root, collar rots and leaf blights. The first Phytophthora study on forest trees in Turkey was made on oak species which is the most widespread tree in the country. Seven Phytophthora species, namely P. cinnamomi, P. citricola, P. cryptogea, P. gonapodyides, P. quercina, Phytophthora sp. 1 and Phytophthora sp. 2’ were found to cause dieback and death on oaks, P. quercina being the most frequently encountered. The second most common tree having Phytophthora infections is sweet chestnut and root rots caused by Phytophthora were determined everywhere chestnut grow in the country. Four species were found on chestnut and the most frequently occurring two species are P. cambivora and P. cinnamomi occurring in the inner part and in the coastal areas of the country respectively. The third and fourth species, P. plurivora and P. cryptogea were observed in the decreasing order respectively. From the above mentioned species, P. cambivora and P. cryptogea were also reported from black pine at one location in the newly reforested location. From the other forest trees; various Phytophthora species were reported; P. lacustris from narrow leaved ash, P. plurivora, P. occultans from boxwood, P. citrophthora and P. cactorum from horse chestnut, P. nicotianae from Ailanthus sp. Phytophthora diseases were also found in a few nurseries growing forest an ornamental trees. P. cinnamomi, P. cryptogea, P. cactorum, P. citricola, P. megasperma and P. syringae were found to cause disease on various forest tree saplings. Elaborate information on Phytophthora diseases is being given in the review.

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Allou Isidore, SARAKA, ABO Kouabenan, OUATTARA Katinan Etienne et ZIRIHI Guédé Noël. « Étude botanique, tri phytochimique et évaluation in vitro de l’activité antifongique des extraits de feuilles de Mallotus oppositifolius (Geisel.) Müll. Arg (Euphorbiaceae) sur Fusarium sp. et Phytophthora sp. deux champignons phytopathogènes ». Journal of Animal & ; Plant Sciences 41.2 (31 août 2019) : 6903–15. http://dx.doi.org/10.35759/janmplsci.v41-2.4.

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L’objectif de ce travail est d’évaluer le pouvoir fongicide des feuilles de Mallotus oppositifolius sur Phytophthora sp. et Fusarium sp. deux champignons phytopathogènes dans le cadre de la recherche de substances naturelles d’origine végétale comme alternative aux pesticides chimiques en agriculture. Une enquête ethnobotanique réalisée auprès de quarante tradipraticiens de santé du District de Yamoussoukro sur les Euphorbiaceae médicinales a permis d’identifier treize espèces. L’étude a montré que les maladies de la peau (36%) étaient majoritairement traitées par ces Euphorbiaceae dont Mallotus oppositifolius. Au vue de ces données et celles de la littérature, Mallotus oppositifolius a été retenu pour l’évaluation du potentiel antifongique contre Fusarium sp. et Phytophthora sp. L'activité antifongique a été évaluée par la méthode de double dilution sur milieu PDA avec des extraits éthanoliques et aqueux dérivés des feuilles de cette plante. Les résultats ont montré que les extraits aqueux et éthanoliques 70% de Mallotus oppositifolius possèdent des propriétés antifongiques à la fois sur Fusarium sp. et Phytophthora sp. Les activités antifongiques ont été plus importantes avec les extraits éthanoliques qu’avec les extraits aqueux. Avec une concentration minimal inhibitrice CMI = 25±0,0 mg/mL, une CI50 = 6,5±0,05 mg/mL et une concentration minimal fongicide CMF = 200±0,0 mg/mL Fusarium sp. semble être le plus sensible. Phytophthora sp. est moins sensible avec une CMI = 50±0,0 mg/mL, une CI50 = 12±0,05 mg/mL et une CMF = 200±0,0 mg/mL. Le screening phytochimique a mis en évidence la présence de sept groupes de composés parmi lesquels les alcaloïdes, les polyterpènes et stérols, les tanins galliques et les catéchines sont les plus abondants dans les extraits éthanoliques. En plus de ces composés, les flavonoïdes, les polyphénols ainsi que les saponines sont aussi bien présents dans les extraits aqueux que dans les extraits alcooliques de Mallotus oppositifolius. Ces composés pourraient justifier l’activité des extraits éthanoliques de Mallotus oppositifolius. Ces résultats peuvent servir pour les recherches agronomiques dans le cadre de la lutte contre les deux champignons phytopathogènes étudiés. Botanical study, phytochemical screening and in vitro evaluation of the antifungal activity of Mallotus oppositifolius (Geisel.) Müll. Arg. (Euphorbiaceae) leaf extracts on Fusarium sp. and Phytophthora sp., two phytopathogenic fungi. ABSTRACT The purpose of this work is to evaluate the fungicidal power of the leaves of Mallotus oppositifolius on Phytophthora sp. and Fusarium sp. two phytopathogenic fungi in the research of natural substances of plant origin as an alternative to chemical pesticides in agriculture. An ethnobotanical survey of forty traditional healers in the Yamoussoukro District on medicinal Euphorbiaceae identified thirteen species.The study showed that skin diseases (36%) were mainly treated by these Euphorbiaceae including Mallotus oppositifolius. In view of these data and those in the literature, Mallotus oppositifolius was selected for the evaluation of the antifungal potential against Fusarium sp. and Phytophthora sp. The antifungal activity was evaluated by the double dilution method on PDA medium with ethanolic and aqueous extracts derived from the leaves of this plant. The results showed that aqueous and ethanolic extracts 70% of Mallotus oppositifolius have antifungal properties on both Fusarium sp. and Phytophthora sp. Antifungal activities were more important with ethanolic extracts than with aqueous extracts. With a minimum inhibitory concentration MIC = 25±0.0 mg/mL, a minimal concentration for 50 % of inhibition IC50 = 6.5±0.05 mg/mL and a minimum fungicide concentration MFC = 200±0.0 mg/mL Fusarium sp. appears to be the most sensitive. Phytophthora sp. is less sensitive with an MIC = 50±0.0 mg/mL, an IC50 = 12±0.05 mg/mL and a MFC = 200±0.0 mg/mL. Phytochemical screening revealed the presence of seven groups of compounds among which alkaloids, polyterpenes and sterols, gallic tannins and catechins are the most abundant in ethanol extracts. In addition to these compounds, flavonoids, polyphenols and saponins are present in both aqueous and alcoholic extracts of Mallotus oppositifolius. These compounds could justify the activity of the ethanolic extracts of Mallotus oppositifolius. These results can be used for agronomic research to control the two phytopathogenic fungi studied.

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Juhásová, G., et S. Bernadovičová. « Efficacy of biofungicides Supresivit and Polyversum against Phytophthora root pathogens on European chestnut (Castanea sativa Mill.) ». Horticultural Science 31, No. 3 (25 novembre 2011) : 109–14. http://dx.doi.org/10.17221/3802-hortsci.

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The effect of two commercially produced biopreparations on the originators of chestnut ink disease in Slovakia – soil fungi Phytophthora cambivora and Phytophthora cinnamomi was tested in laboratory conditions. Investigations of interrelations between Trichoderma harzianum (Pythium oligandrum) and isolates of Phytophthora sp. obtained from infected tissues of Castanea sativa Mill. proved more important inhibitive effects for Pythium oligandrum (biopreparation Polyversum) efficiency 25.3% (Ph. cambivora) and 26.2% (Ph. cinnamomi). Biopreparation Supresivit (Trichoderma harzianum) reached the efficiency 9.1% for Ph. cambivora isolates and 9.2% for Ph. cinnamomi isolates. Significant effect of the used bioformulas for inhibition of mycelial growth of both Phytophthora sp. and significant difference in the efficacy of two different bioformulas were confirmed statistically.  

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Calderón Díaz, José Humberto, et María del Carmen Santos Bravo. « Identificación de microorganismos del género Phytophthora asociados a especies de Quercus sp. y Pinus sp., en los departamentos de Guatemala y Sacatepéquez ». Ciencia, Tecnología y Salud 2, n^o 1 (1 juillet 2015) : 47–52. http://dx.doi.org/10.36829/63cts.v2i1.59.

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El objetivo principal fue la identificación de microorganismos del género Phytophthora que afectan a bosques naturales mixtos y viveros de Pinus sp. y Quercus sp., con importancia socioeconómica, en los departamentos de Guatemala y Sacatepéquez. Para el aislamiento de Phytophthora se procesaron muestras de suelo y tejido vegetal.En el departamento de Guatemala, del bosque natural se obtuvieron 10 muestras de Quercus sp. y 45 de Pinus sp., de los viveros se obtuvieron 11 muestras de Quercus sp. y 88 de Pinus sp. En el departamento de Sacatepéquez se obtuvieron del bosque natural 15 muestras de Quercus sp. y 48 de Pinus sp.; y en los viveros, 58 muestras de Pinus sp. y 25 de Quercus sp. Un total de 13 muestras procedentes de los viveros fueron positivas a la presencia de Phytophthora sp. en Pinus maximinoi, 10 procedentes del departamento de Guatemala, y tres de Sacatepéquez. Referente al tipo de crecimiento de la colonia en medio PDA, se obtuvieron cinco de tipo estolonífero, cinco tipo semipetaloide, una colonia de tipo estelado y dos colonias sin ningún tipo de patrón de crecimiento. Las pruebas de patogenicidad realizadas con la cepa VP16 mostraron alta incidencia y severidad para las especies de Pinus caribaea, P. oocarpa, P. pseudostrobus, P. maximinoi y en menor grado en Pinus tecunumanii.

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Richard, C., et J. G. Martin. « Pourriture phytophthoréenne de la luzerne au Québec : distribution géographique des symptômes et étude des facteurs édaphiques pouvant favoriser leur expression ». Phytoprotection 72, n^o 3 (12 avril 2005) : 87–95. http://dx.doi.org/10.7202/706008ar.

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Nous avons observé chez la luzerne (Medicago sativa) des symptômes attribuables à la pourriture phytophthoréenne (Phytophthora megasperma f. sp. medicaginis) dans les 12 régions agricoles du Québec, avec une présence plus marquée dans l'Outaouais, la Beauce, les Cantons de l'Est, la région de Québec et le Nord de Montréal. Les symptômes de pourriture étaient plus présents dans les dépressions des luzernières échantillonnées. Nous avons déterminé la texture et la capacité de rétention d'eau des sols échantillonnés, et trouvé aucune relation avec la pourriture phytophthoréenne. La culture de cultivars de luzerne résistants ou sensibles dans ces sols en serre ne montre pas de différence de maladie. Seulement quatre isolats du Phytophthora megasperma f. sp. medicaginis et un du Phytophthora cryptogea ont été obtenus. Lors d'un essai en serre, le trèfle rouge (Trifolium pratense) ne fut pas sensible à l'attaque par le P. megasperma f. sp. medicaginis. Le peu de succès à isoler et démontrer la présence du P. megasperma f. sp. medicaginis dans les sols où l'on observe pourtant des symptômes semblables à ceux de la pourriture phytophthoréenne porte à penser qu'en plus du Phytophthora, d'autres causes comme l'anoxie ou l’Aphanomyces euteiches pourraient en être responsables.

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Dobbie, Kiryn, Peter Scott, Pam Taylor, Preeti Panda, Diya Sen, Margaret Dick et Rebecca McDougal. « Phytophthora podocarpi sp. nov. from Diseased Needles and Shoots of Podocarpus in New Zealand ». Forests 13, n^o 2 (31 janvier 2022) : 214. http://dx.doi.org/10.3390/f13020214.

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Foliage samples from Podocarpus totara with severe needle browning and needle loss in the lower part of the crown were observed in 2011 in the Gisborne region of New Zealand. A Phytophthora genus-specific test applied directly to the needles gave a strong positive result, and subsequent isolations yielded colonies of a slow-growing oomycete. Morphological examination in vitro revealed a Phytophthora species. Preliminary comparisons of the rDNA (ITS), and ras-related protein (Ypt) gene regions with international DNA sequence revealed low sequence similarity to species from the downy mildew genus Peronospora, as well as clade 3 Phytophthora species. Other studies have also demonstrated the close relationship with Peronospora. The species was given the interim designation Phytophthora taxon tōtara pending further examination. Here, we formally describe Phytophthora podocarpi sp. Nov. and its associated disease, tōtara needle blight.

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Whisson, SC, BJ Howlett, ECY Liew, DJ Maclean, JM Manners et JAG Irwin. « An Assessment of Genetic Relationships between Members of the Phytophthora megasperma Complex and Phytophthora vignae using Molecular Markers ». Australian Systematic Botany 6, n^o 4 (1993) : 295. http://dx.doi.org/10.1071/sb9930295.

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Genetic relationships between Phytophora megasperma f. sp. glycinea (Pmg) and morphologically similar taxa, P. megasperma f. sp. medicaginis (Pmm), P. megasperma f. sp. trifolii (Pmt), P. megasperma from Douglas Fir (PmDF) and asparagus (PmAS) and Phytophthora vignae, were explored by restriction fragment length polymorphism (RFLP) analysis of nuclear DNA using random genomic multi-copy, cDNA, and ribosomal DNA probes as well as random amplified polymorphic DNA (RAPDs) and RFLP analysis of ribosomal intergenic spacer regions amplified by the polymerase chain reaction (PCR). Each method detected large differences between these taxa and P. megasperma f. sp. glycinea. P. vignae was more closely related to P. megasperma f. sp. glycinea than the other taxa on the basis of the cDNA RFLPs and RFLPs of PCR amplified rDNA intergenic spacer regions. We conclude that each of the taxa examined represent separate species. This supports the most recent reclassification based on mitochondrial RFLPs and electrophoretic protein patterns of the host-specific taxa to P. sojae (Pmg), P. trifolii (Pmt) and P. medicaginis (Pmm).

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Grünwald, N. J., S. Werres, E. M. Goss, C. R. Taylor et V. J. Fieland. « Phytophthora obscura sp. nov., a new species of the novel Phytophthora subclade 8d ». Plant Pathology 61, n^o 3 (9 octobre 2011) : 610–22. http://dx.doi.org/10.1111/j.1365-3059.2011.02538.x.

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AGHAYEV, Jabrayil, et Samadova EZET. « Diseases of Tomato in the Conditions of Azerbaijan ». Eurasia Proceedings of Health, Environment and Life Sciences 5 (5 août 2022) : 106–11. http://dx.doi.org/10.55549/ephels.61.

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According to research 2001-2018 in Absheron, Lankaran-Astara and Guba- Khachmas regions dynamics and spread of major malware disease progressed. Among the most harmful diseases, as Phytophthora infenstans (M.) de Bary, Phytophthora SP., Alternaria solani Sor. Alternaria alternata, aggressive species from the genera of Fusarium and Vertisillium, Pseudomonas sp. causing wilt of seedlings, fruit rot of different origin, mosaic and leaf curling caused by viruses, gall nematodes (Meloidegine incoqnita, M. arenarea).

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Ablett, G. R., B. T. Stirling et J. D. Fischer. « RCAT Columbus soybean ». Canadian Journal of Plant Science 76, n^o 1 (1 janvier 1996) : 135–36. http://dx.doi.org/10.4141/cjps96-023.

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RCAT Columbus is a late Maturity Group II soybean [Glycine max (L.) Merr.] cultivar with excellent yield potential and lodging resistance and with good tolerance to phytophthora root rot caused by Phytophthora megasperma f. sp. glycinea. Key words: Soybean, cultivar description

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Silva Acosta, Gabriel Ernesto, et Alberto Rafael Paez Redondo. « Antagonismo in vitro de nueve hongos aislados del Caribe colombiano sobre Phytophthora sp. asociado a palma aceitera ». Ingeniería y Desarrollo 39, n^o 02 (14 février 2022) : 205–20. http://dx.doi.org/10.14482/inde.39.2.579.546.

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Phytophthora palmivora se asocia como causante de la pudrición del cogollo (PC), enfermedad que afecta el rendimiento y supervivencia de las plantaciones de palma aceitera en Colombia. Con el objetivo de explorar alternativas de control biológico a la PC se evaluó en in vitro la acción antagónica de nueve cepas de hongos filamentosos: Aspergillus clavatus, Aspergillus glaucus, Aspergillus niger, Aspergillus nidulans, Aspergillus terreus, Penicillium sp. 01, Penicillium sp. 02, Paecilomyces variotii y Trichoderma sp. contra Phytophthora sp. aislado de palma aceitera, más un tratamiento control. Se estableció un diseño de bloques completos al azar con cuatro repeticiones y se usó la técnica del plato dual en cajas Petri (Ø = 90 mm) con agar papa destroza. Se midieron las variables crecimiento micelial radial (CMR), tasa de crecimiento micelial (TCM) y grado de inhibición (GI), a las 96 horas de incubación de los tratamientos. Trichoderma sp. y A. niger fueron estadísticamente superior a los demás tratamientos (p?0,01), ejerciendo un 79 y 74 % de GI sobre el oomycete, respectivamente, restringiendo su CMR entre 2 a 2,3 cm y limitando su TCM hasta 4 veces menos respecto al control. Tres conglomerados jerárquicos fueron formados entre los nueve aislamientos por su comportamiento antagónico contra Phytophthora sp. Los aislados sobresalientes muestran potencial como biorreguladores del patógeno.

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Ann, P. J., et W. H. Ko. « An asexual variant of Phytophthora insolita ». Canadian Journal of Microbiology 40, n^o 10 (1 octobre 1994) : 810–15. http://dx.doi.org/10.1139/m94-129.

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All tested isolates of Phytophthora insolita and an unknown asexual Phytophthora species found in soil, ditch water, and diseased plant tissues in Taiwan produced ovoid, nonpapillate, nondeciduous sporangia on sporangiophores proliferating through an empty sporangium or in a nesting fashion, and formed irregular as well as spherical hyphal swellings. All tested Phytophthora isolates grew at an unusually high temperature of 39 °C, displayed similar or identical electrophoretic patterns of soluble proteins, and produced α1 hormone. The ability of one isolate of P. insolita to produce oospores was decreased and that of another was lost completely during storage. The results suggest that all isolates of the asexual Phytophthora sp. tested were Phytophthora insolita and were unable to produce oospores owing to a defect in the physiological process of sexual reproduction.Key words: asexual Phytophthora, Phytophthora insolita, high-temperature Phytophthora, sexual reproduction.

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Xu, Huai, Hamiti, Zhang et Zhao. « Phytophthora Species from Xinjiang Wild Apple Forests in China ». Forests 10, n^o 10 (21 octobre 2019) : 927. http://dx.doi.org/10.3390/f10100927.

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Phytophthora species are well-known destructive forest pathogens, especially in natural ecosystems. The wild apple (Malus sieversii (Ledeb.) Roem.) is the primary ancestor of M. domestica (Borkh.) and important germplasm resource for apple breeding and improvement. During the period from 2016 to 2018, a survey of Phytophthora diversity was performed at four wild apple forest plots (Xin Yuan (XY), Ba Lian (BL), Ku Erdening (KE), and Jin Qikesai (JQ)) on the northern slopes of Tianshan Mountain in Xinjiang, China. Phytophthora species were isolated from baiting leaves from stream, canopy drip, and soil samples and were identified based on morphological observations and the rDNA internal transcribed spacer (ITS) sequence analysis. This is the first comprehensive study from Xinjiang to examine the Phytophthora communities in wild apple forests The 621 resulting Phytophthora isolates were found to reside in 10 different Phytophthora species: eight known species (P. lacustris being the most frequent, followed by P. gonapodyides, P. plurivora, P. gregata, P. chlamydospora, P. inundata, P. virginiana, and P. cactorum) and two previously unrecognized species (P. sp. CYP74 and P. sp. forestsoil-like). The highest species richness of Phytophthora occurred at BL, followed by XY. P. lacustris was the dominant species at BL, XY, and JQ, while P. gonapodyides was the most common at KE. In the present paper, the possible reasons for their distribution, associated implications, and associated diseases are discussed.

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Oszust, Karolina, Justyna Cybulska et Magdalena Frąc. « How Do Trichoderma Genus Fungi Win a Nutritional Competition Battle against Soft Fruit Pathogens ? A Report on Niche Overlap Nutritional Potentiates ». International Journal of Molecular Sciences 21, n^o 12 (14 juin 2020) : 4235. http://dx.doi.org/10.3390/ijms21124235.

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We present a case study report into nutritional competition between Trichoderma spp. isolated from wild raspberries and fungal phytopathogenic isolates (Colletotrichum sp., Botrytis sp., Verticillium sp. and Phytophthora sp.), which infect soft fruit ecological plantations. The competition was evaluated on the basis of nutritional potentiates. Namely, these were consumption and growth, calculated on the basis of substrate utilization located on Biolog® Filamentous Fungi (FF) plates. The niche size, total niche overlap and Trichoderma spp. competitiveness indices along with the occurrence of a stressful metabolic situation towards substrates highlighted the unfolding step-by-step approach. Therefore, the Trichoderma spp. and pathogen niche characteristics were provided. As a result, the substrates in the presence of which Trichoderma spp. nutritionally outcompete pathogens were denoted. These were adonitol, D-arabitol, i-erythritol, glycerol, D-mannitol and D-sorbitol. These substrates may serve as additives in biopreparations of Trichoderma spp. dedicated to plantations contaminated by phytopathogens of the genera Colletotrichum sp., Botrytis sp., Verticillium sp. and Phytophthora sp.

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Burgess, T. I., Q. N. Dang, B. V. Le, N. Q. Pham, D. White et T. Q. Pham. « Phytophthora acaciivora sp. nov. associated with dying Acacia mangium in Vietnam ». Fungal Systematics and Evolution 6, n^o 1 (15 décembre 2020) : 243–52. http://dx.doi.org/10.3114/fuse.2020.06.11.

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Acacia mangium plantations account for more than 50 % of the exotic plantations in Vietnam. A new black butt symptom was discovered in 2012, followed by the wilting sign in Acacia seedlings in Tuyen Quang Province. Isolations recovered two Phytophthora species, the well-known Acacia pathogen P. cinnamomi, and an unknown species. The new species is described here as Phytophthora acaciivora sp. nov. Phylogenetically this species resides in clade 2d and is most closely related to P. frigida. Phytophthora acaciivora is a heterothallic species, oospores are aplerotic and antheridia are amphigynous. It produces predominantly elongated ovoid, semi papillate, persistent sporangia, no hyphal swellings and no chlamydospores. Optimum temperature for the growth is 25–30 °C and the maximum temperature is over 37.5 °C. Studies are underway to determine the impact of this new species on Acacia plantations in Vietnam.

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Ablett, G. R., et J. W. Tanner. « RCAT Angora soybean ». Canadian Journal of Plant Science 73, n^o 1 (1 janvier 1993) : 179–80. http://dx.doi.org/10.4141/cjps93-026.

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RCAT Angora is a mid-late Maturity Group II soybean (Glycine max (L.) Merr.) cultivar with excellent yield potential and resistance to most races of phytophthora root rot caused by Phytophthora megasperma f. sp. glycinea (RMG) found in Ontario. Key words: Soybean, cultivar description

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Weir, Bevan Simon, ELSA P. PADERES, NITISH ANAND, JANICE Y. UCHIDA, SHAUN R. PENNYCOOK, STANLEY E. BELLGARD et ROSS E. BEEVER. « A taxonomic revision of Phytophthora Clade 5 including two new species, Phytophthora agathidicida and P. cocois ». Phytotaxa 205, n^o 1 (10 avril 2015) : 21. http://dx.doi.org/10.11646/phytotaxa.205.1.2.

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Phytophthora Clade 5 is a very poorly studied group of species of oomycete chromists, consisting of only two known species P. castaneae (≡ P. katsurae, nom. illegit.) and P. heveae with most isolates from East Asia and the Pacific Islands. However, isolates of two important disease-causing chromists in Clade 5, one of kauri (Agathis australis) in New Zealand, the other of coconut (Cocos nucifera) in Hawaii, poorly match the current species descriptions. To verify whether these isolates belong to separate species a detailed morphological study and phylogenetic analysis consisting of eight genetic loci was conducted. On the basis of genetic and morphological differences and host speciﬁcity, we present the formal description of two new species in Clade 5, Phytophthora agathidicida sp. nov. and Phytophthora cocois sp. nov. To clarify the typification of the other Clade 5 species, an authentic ex-holotype culture of Phytophthora castaneae is designated and P. heveae is lectotypified and epitypified.

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Singh, U. P., et V. B. Chauhan. « Oospore Formation in Phytophthora drechsleri f. sp. cajani ». Journal of Phytopathology 123, n^o 1 (septembre 1988) : 89–91. http://dx.doi.org/10.1111/j.1439-0434.1988.tb01040.x.

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GEESON, J. D., K. M. BROWNE et B. McKEOWN. « Storage rot of swede caused by Phytophthora sp. » Plant Pathology 39, n^o 4 (décembre 1990) : 629–31. http://dx.doi.org/10.1111/j.1365-3059.1990.tb02545.x.

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Jiménez-Camargo, Abraham, Ernestina Valadez-Moctezuma et Héctor Lozoya-Saldaña. « ANTAGONISMO DE Penicillium sp. CONTRA Phytophthora capsici (Leonian) ». Revista Fitotecnia Mexicana 41, n^o 2 (7 juin 2018) : 137–48. http://dx.doi.org/10.35196/rfm.2018.2.137-148.

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La marchitez del chile (Capsicum annuum) es causada por un complejo de hongos fitopatógenos del suelo, entre los que se encuentra Phytophthora capsici (Leonian) y ocasiona pérdidas en rendimiento del fruto desde el 10 hasta el 100 %; no obstante, hay suelos supresores que contienen microorganismos como Penicillium sp., antagónicos al oomiceto. Con este antecedente, se hicieron recolectas de ambos microorganismos en campo, mayormente en el Bajío guanajuatense, México, con el objetivo de identificar posible variabilidad a nivel molecular entre las cepas de los microorganismos aislados y su relación con su acción antagónica. Se determinaron los efectos antagónicos in vitro e in vivo de aislados selectos de Penicillium spp. sobre la cepa de P. capsici identificada como la más agresiva, así como el modo del control biológico del antagonista. Los agrupamientos de las cepas de Penicillium spp. no coincidieron con su acción antagónica sobre P. capsici (agrupamientos distantes ejercieron acciones similares de antagonismo), aunque la agresividad de P. capsici sí se asoció con un grupo en el que diferentes enzimas de restricción (Hha I, Hinf I y Hae III) no detectaron polimorfismos. De las 47 cepas de Penicillium spp. y siete de P. capsici obtenidas, se seleccionaron 30 del antagonista para la confrontación in vitro con la cepa más agresiva de P. capsici. Con los resultados de este ensayo se seleccionaron nueve antagonistas para la confrontación in vivo, de los que sobresalieron en esta prueba seis aislamientos, que sólo permitieron de 5 a 21 % de infección, en comparación con 85 % del testigo inoculado con el patógeno en ausencia de antagonistas. El efecto antagónico fue una combinación de inhibición por antibiosis, competencia por espacio y desintegración de micelio.

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Ablett, G. R., et W. D. Beversdorf. « RCAT Persian soybean ». Canadian Journal of Plant Science 71, n^o 1 (1 janvier 1991) : 175–76. http://dx.doi.org/10.4141/cjps91-018.

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RCAT Persian is a mid-late Maturity Group I soybean [Glycine max L. (Merr.)] cultivar with excellent yield potential, good lodging tolerance and resistance to most races of phytophthora root rot caused by Phytophthora megasperma f. sp. glycinea (Pmg) found in Ontario. Key words: Soybean, cultivar description

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Ablett, G. R., et J. W. Tanner. « Brock soybean ». Canadian Journal of Plant Science 73, n^o 1 (1 janvier 1993) : 175–76. http://dx.doi.org/10.4141/cjps93-024.

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Brock is a mid-Maturity Group I soybean (Glycine max (L.) Merr.) cultivar with excellent yield potential and lodging tolerance and with resistance to most races of phytophthora root rot caused by Phytophthora megasperma f. sp. glycinea (PMG) found in Ontario. Key words: Soybean, cultivar description

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Ablett, G. R., et J. W. Tanner. « RCAT Tabby soybean ». Canadian Journal of Plant Science 73, n^o 4 (1 octobre 1993) : 1103–4. http://dx.doi.org/10.4141/cjps93-148.

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RCAT Tabby is a mid Maturity Group II soybean [Glycine max (L.) Merr.] cultivar with excellent yield potential, lodging resistance and with resistance to most races of phytophthora root rot caused by Phytophthora megasperma f. sp. glycinea (PMG) found in Ontario. Key words: Soybean, cultivar description

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Hong, C. X., M. E. Gallegly, G. T. Browne, R. G. Bhat, P. A. Richardson et P. Kong. « The avocado subgroup of Phytophthora citricola constitutes a distinct species, Phytophthora mengei sp. nov. » Mycologia 101, n^o 6 (novembre 2009) : 833–40. http://dx.doi.org/10.3852/08-214.

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Khaliq, Ihsanul, Giles E. St. J. Hardy, Keith L. McDougall et Treena I. Burgess. « Phytophthora species isolated from alpine and sub-alpine regions of Australia, including the description of two new species ; Phytophthora cacuminis sp. nov and Phytophthora oreophila sp. nov ». Fungal Biology 123, n^o 1 (janvier 2019) : 29–41. http://dx.doi.org/10.1016/j.funbio.2018.10.006.

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Mrázková, M., K. Černý, M. Tomšovský et V. Strnadová. « Phytophthora plurivora T. Jung & ; T. I. Burgess and other Phytophthora species causing important diseases of ericaceous plants in the Czech Republic ». Plant Protection Science 47, No. 1 (1 mars 2011) : 13–19. http://dx.doi.org/10.17221/3108-pps.

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Ornamental nurseries, garden centres, public gardens and urban greenery in the Czech Republic were surveyed in 2006–2009 for the presence of Phytophthora spp. and the diseases they cause on ericaceous plants. Diseased plants such as Rhododendron spp., Pieris floribunda, Vaccinium sp., and Azalea sp. showed various symptoms including leaf spot, shoot blight, twig lesions or stem, root and collar rot. Nearly 140 Phytophthora isolates were collected from symptomatic plants in different areas of the country. Of the Phytophthora spp. on ericaceous plants or in their surroundings, P. plurivora appeared to be the most common species. Herein, we focus on the most frequently occurring species, P. plurivora, and describe its morpho-physiological and pathogenicity features and confirm its identity based on ITS sequences of rDNA. In addition, we give a list of other Phytophthora spp. including P. cactorum, P. cambivora, P. cinnamomi, P. citrophthora, P. megasperma, P. multivora, P. ramorum, and P. gonapodyides that we identified on the basis of their cultural and morphological characteristics and DNA sequences. We also discuss their importance in cultivated and natural ecosystems.

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Pérez-Sierra, A., M. León, L. A. Álvarez, S. Alaniz, M. Berbegal, J. García-Jiménez et P. Abad-Campos. « Outbreak of a New Phytophthora sp. Associated with Severe Decline of Almond Trees in Eastern Spain ». Plant Disease 94, n^o 5 (mai 2010) : 534–41. http://dx.doi.org/10.1094/pdis-94-5-0534.

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Since 2007, a decline of young almond trees (Prunus dulcis) has been observed in different field-grown nurseries in Valencia (east-central Spain). Early symptoms in affected trees included chlorosis, wilting, cankers, and profuse stem gumming. A Phytophthora sp. was consistently isolated from cankers, roots, and soil of affected trees. It was a heterothallic species with amphigynous and/or paragynous antheridia, and its morphological features did not conform to any of the described Phytophthora species. Pathogenicity was proved by artificial inoculation, completing Koch's postulates. All isolates were sensitive to the phenylamide fungicides metalaxyl and mefenoxam. Amplification and sequencing of the internal transcribed spacer (ITS) region, translation elongation factor 1 alpha gene (EF-1α), the β-tubulin (β-tub) gene, and the region containing the mitochondrial cytochrome c oxidase subunit 1 (cox1) gene fragment identified the species as Phytophthora taxon “niederhauserii”, and phylogenetic analyses placed it in Phytophthora Clade 7b.

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Gastañadui, Paul, Rocío Moreno, Patricia Elena Quiroz-Delgado et Walter Eduardo Apaza-Tapia. « Control of avocado root rot caused by Phytophthora cinnamomi with different Trichoderma strains at Chavimochic Irrigation Project ». Peruvian Journal of Agronomy 5, n^o 3 (30 décembre 2021) : 78–86. http://dx.doi.org/10.21704/pja.v5i3.1846.

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Avocado root rot caused by Phytophthora cinnamomi is one of the main problems affecting avocado (Persea americana) cultivation in Peru, especially at the Chavimochic Irrigation Project. The objective of this study was to evaluate the effect of different Trichoderma strains on the control of Phytophthora cinnamomi in Zutano rootstock under greenhouse conditions. Five isolates of Trichoderma were tested: Trichoderma sp. (Chav01); Trichoderma harzianum (Chavo2); Trichoderma harzianum (UNALM01); Trichoderma viride (UNALM02); and a commercial strain of Trichoderma sp. Evaluations were performed at 30, 45, and 60 days. All isolates colonized the rhizosphere of the avocado. No relation was found between the formation of more Trichoderma colonies and Phytophthora improved control. All strains controlled the root rot, but Chav01 and Chav02 showed the greatest diameter of stem, dry matter in the root, and percentage of healthy root in comparison with UNALM01, UNALM02, and the commercial strain. Thus, the native isolates of Trichoderma from the Chavimochic area can be added to the list of potential new Trichoderma species to control Phytophthora cinnamomi.

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ANDERSON, T. R., et R. I. BUZZELL. « "DEFEATED" Rps1 GENE IN SOYBEAN ». Canadian Journal of Plant Science 68, n^o 1 (1 janvier 1988) : 225–27. http://dx.doi.org/10.4141/cjps88-026.

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Field testing of 10 backcross-derived Rps1Rps1 cultivars/lines of soybean (Glycine max (L.) Merr.) and their recurrent rps1rps1 cultivars in the presence of compatible races of Phytophthora megasperma f. sp. glycinea showed no residual effects of race-specific resistance on tolerance of soybean to the disease.Key words: Soybean, race-specific resistance, tolerance, phytophthora rot

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Scanu, Bruno, Thomas Jung, Hossein Masigol, Benedetto Teodoro Linaldeddu, Marília Horta Jung, Andrea Brandano, Reza Mostowfizadeh-Ghalamfarsa, Josef Janoušek, Mario Riolo et Santa Olga Cacciola. « Phytophthora heterospora sp. nov., a New Pseudoconidia-Producing Sister Species of P. palmivora ». Journal of Fungi 7, n^o 10 (16 octobre 2021) : 870. http://dx.doi.org/10.3390/jof7100870.

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Since 1999, an unusual Phytophthora species has repeatedly been found associated with stem lesions and root and collar rot on young olive trees in Southern Italy. In all cases, this species was obtained from recently established commercial plantations or from nursery plants. Morphologically, the Phytophthora isolates were characterized by the abundant production of caducous non-papillate conidia-like sporangia (pseudoconidia) and caducous papillate sporangia with a short pedicel, resembling P. palmivora var. heterocystica. Additional isolates with similar features were obtained from nursery plants of Ziziphus spina-christi in Iran, Juniperus oxycedrus and Capparis spinosa in Italy, and mature trees in commercial farms of Durio zibethinus in Vietnam. In this study, morphology, breeding system and growth characteristics of these Phytophthora isolates with peculiar features were examined, and combined mitochondrial and nuclear multigene phylogenetic analyses were performed. The proportion between pseudoconidia and sporangia varied amongst isolates and depended on the availability of free water. Oogonia with amphigynous antheridia and aplerotic oospores were produced in dual cultures with an A2 mating type strain of P. palmivora, indicating all isolates were A1 mating type. Phylogenetically, these isolates grouped in a distinct well-supported clade sister to P. palmivora; thus, they constitute a separate taxon. The new species, described here as Phytophthora heterospora sp. nov., proved to be highly pathogenic to both olive and durian plants in stem inoculation tests.

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Santos, Álvaro F. dos, Edna Dora M. N. Luz et Jorge Teodoro de Souza. « Phytophthora nicotianae : agente etiológico da gomose da acácia-negra no Brasil ». Fitopatologia Brasileira 30, n^o 1 (février 2005) : 81–84. http://dx.doi.org/10.1590/s0100-41582005000100015.

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A gomose, causada por Phytophthora sp., é a mais importante enfermidade da acácia-negra (Acacia mearnsii) no Rio Grande do Sul, Brasil. A identificação específica permanecia indeterminada. Procurou-se, então, identificar a espécie de Phytophthora causadora desta doença no Rio Grande do Sul, usando características fisiomorfológicas e estudos moleculares baseados no seqüenciamento das regiões de Internal Transcribed Spacer (ITS). A patogenicidade dos isolados estudados para a acácia-negra foi confirmada. Os estudos confirmaram Phytophthora nicotianae como a correta identidade dos isolados fitopatogênicos. Este é o primeiro relato de P. nicotianae em acácia-negra no Brasil.

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Saude, C., M. K. Hausbeck, O. Hurtado-Gonzales et K. H. Lamour. « Detection of a Phytophthora sp. Causing Asparagus Spear and Root Rot in Michigan ». Plant Disease 89, n^o 9 (septembre 2005) : 1011. http://dx.doi.org/10.1094/pd-89-1011b.

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In the spring of 2004, a Phytophthora sp. was isolated from asparagus (Asparagus officinalis) spears, roots, and dormant crowns from several fields in Oceana and Ingham counties in Michigan. Symptomatic spears were often curved, had water-soaked lesions slightly above or below the soil line or were shriveled at the site of infection or both. Infected storage roots had water-soaked lesions but were not soft at the lesion site. Infected crowns had fewer roots than healthy crowns. In the laboratory, plant tissues were rinsed in tap water and blotted dry. Sections from the edge of lesions were placed aseptically onto BARP (25 ppm of benomyl, 100 ppm of ampicillin, 30 ppm of rifampicin, and 100 ppm of pentachloroni-trobenzene) amended unclarified V8 juice agar and incubated at 25°C for up to 7 days. Phytophthora sp. isolates recovered from the infected material produced ovoid, nonpapillate, noncaducous sporangia and amphigy-nous oospores on isolation media. Single-sporangium cultures made for each isolate were stored long term in sterile 2-ml microcentrifuge tubes containing two 7-mm mycelial plugs, two sterile hemp seeds, and 1 ml of sterile distilled water. Sporangia produced on dilute V8 juice agar averaged 45 μm long × 26 μm wide and oospores were 25 to 30 μm in diameter. Chlamydospores were not observed. Five detached ‘Jersey Knight’ spears were inoculated with a 7-mm mycelial plug from the edge of actively growing 5-day-old cultures and incubated at 23 to 25°C for 5 to 7 days in a moist chamber. After 3 days, water-soaked lesions and shriveling and curving of the spears were visible on all inoculated spears. The pathogen was always reisolated from the lesion edge. No symptoms were observed when spears were inoculated with sterile V8 juice agar plugs. DNA was extracted from representative isolates, and the nuclear ribosomal internal transcribed spacer (ITS) region was amplified with ITS6 and ITS4 primers and sequenced. A BLAST search of the NCBI database with the ITS sequence revealed Phytophthora sp. UQ2141, Accession No. AF266795, as the closest match with 99% sequence similarity. These results, coupled with the morphological characteristics of the isolates, indicate that the Phytophthora sp. isolated from asparagus in Michigan is among the constituents of Phytophthora spp. included in the P. megasperma clade 6 (2), whose taxa are currently being reevaluated. Although a Phytophthora sp. has been described previously on asparagus (1,3), this is the first report, to our knowledge, of a Phytophthora sp. on asparagus in Michigan. The occurrence of excessive rainfall in the spring of 2004 is likely responsible for widespread disease and considerable yield losses in production fields. References: (1) P. A. Ark and J. T. Barrett. Phytopathology 28:754, 1938. (2) D. E. L. Cooke et al. Fungal Genet. Biol. 30:17, 2000. (3) V. Vujanovic et al. Plant Dis. 87:447, 2003.

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Hardy, GESJ, et K. Sivasithamparam. « Suppression of Phytophthora Root Rot by a Composted Eucalyptus Bark Mix. » Australian Journal of Botany 39, n^o 2 (1991) : 153. http://dx.doi.org/10.1071/bt9910153.

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A potting medium containing composted Eucalyptus (Eucalyptus calophylla and E. diversicolor) barks (CEB) was suppressive in decreasing order to Phytophthora cryptogea, P. nicotianae var. nicotianae, P. citricola, P. drechsleri and P. cinnamomi infections of waratah (Telopea speciosissima) and Banksia occidentalis. Suppressiveness of the CEB appears to be biological, as the CEB became conducive to root rot after steam-sterilisation. A non-composted commercial mix (nurseryman's mix, NM) was conducive to all the Phytophthora spp. tested. Pathogenicity of each Phytophthora sp. varied between the container media. In the NM, P. citricola was the most pathogenic species. Steaming the NM resulted in pathogenicity being similar for all Phytophthora spp. However, this did not happen when the CEB was steamed.

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Naveed, Zunaira, et Gul Ali. « Comparative Transcriptome Analysis between a Resistant and a Susceptible Wild Tomato Accession in Response to Phytophthora parasitica ». International Journal of Molecular Sciences 19, n^o 12 (23 novembre 2018) : 3735. http://dx.doi.org/10.3390/ijms19123735.

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Phytophthora parasitica is one of the most widespread Phytophthora species, which is known to cause multiple diseases in tomato and is capable of infecting almost all plant parts. Our current understanding of tomato-Phytophthora parasitica interaction is very limited and currently nothing is known at the whole genome or transcriptome level. In this study, we have analyzed and compared the transcriptome of a resistant and a susceptible wild tomato accession in response to P. parasitica infection using the RNA-seq technology. We have identified 2657 and 3079 differentially expressed genes (DEGs) in treatment vs control comparison of resistant (Sp-R) and susceptible (Sp-S) samples respectively. Functional annotation of DEGs revealed substantial transcriptional reprogramming of diverse physiological and cellular processes, particularly the biotic stress responses in both Sp-R and Sp-S upon P. parasitica treatment. However, subtle expression differences among some core plant defense related genes were identified and their possible role in resistance development against P. parasitica is discussed. Our results revealed 1173 genes that were differentially expressed only in Sp-R accession upon P. parasitica inoculation. These exclusively found DEGs in Sp-R accession included some core plant defense genes, for example, several protease inhibitors, chitinases, defensin, PR-1, a downy mildew susceptibility factor, and so on, were all highly induced. Whereas, several R genes, WRKY transcriptions factors and a powdery mildew susceptibility gene (Mlo) were highly repressed during the resistance outcome. Analysis reported here lays out a strong foundation for future studies aimed at improving genetic resistance of tomato cultivars against to Phytopphthora species.

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Govers, Laura L., Willem A. Man in ‘t Veld, Johan P. Meffert, Tjeerd J. Bouma, Patricia C. J. van Rijswick, Jannes H. T. Heusinkveld, Robert J. Orth, Marieke M. van Katwijk et Tjisse van der Heide. « Marine Phytophthora species can hamper conservation and restoration of vegetated coastal ecosystems ». Proceedings of the Royal Society B : Biological Sciences 283, n^o 1837 (31 août 2016) : 20160812. http://dx.doi.org/10.1098/rspb.2016.0812.

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Phytophthora species are potent pathogens that can devastate terrestrial plants, causing billions of dollars of damage yearly to agricultural crops and harming fragile ecosystems worldwide. Yet, virtually nothing is known about the distribution and pathogenicity of their marine relatives. This is surprising, as marine plants form vital habitats in coastal zones worldwide (i.e. mangrove forests, salt marshes, seagrass beds), and disease may be an important bottleneck for the conservation and restoration of these rapidly declining ecosystems. We are the first to report on widespread infection of Phytophthora and Halophytophthora species on a common seagrass species, Zostera marina (eelgrass), across the northern Atlantic and Mediterranean. In addition, we tested the effects of Halophytophthora sp. Zostera and Phytophthora gemini on Z. marina seed germination in a full-factorial laboratory experiment under various environmental conditions. Results suggest that Phytophthora species are widespread as we found these oomycetes in eelgrass beds in six countries across the North Atlantic and Mediterranean. Infection by Halophytophthora sp . Zostera, P. gemini , or both, strongly affected sexual reproduction by reducing seed germination sixfold. Our findings have important implications for seagrass ecology, because these putative pathogens probably negatively affect ecosystem functioning, as well as current restoration and conservation efforts.

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Bregant, Carlo, Giovanni Rossetto, Antonio Deidda, Lucia Maddau, Antonio Franceschini, Giorgio Ionta, Alessandro Raiola, Lucio Montecchio et Benedetto T. Linaldeddu. « Phylogeny and Pathogenicity of Phytophthora Species Associated with Artichoke Crown and Root Rot and Description of Phytophthora marrasii sp. nov. » Agriculture 11, n^o 9 (12 septembre 2021) : 873. http://dx.doi.org/10.3390/agriculture11090873.

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Field surveys conducted on nine farms over a 2-year period showed the widespread presence of Phytophthora-related diseases on globe artichoke plants in the main growing area in Sardinia (Italy). Characteristic symptoms included wilting and necrosis of the outermost leaves and dark brown discoloration of stem tissues, as well as root rot. A total of 18 Phytophthora colonies belonging to three species were isolated and characterized. Based on morphological features and ITS sequence data, Phytophthora isolates were identified as P. crassamura (eight isolates) and P. cactorum (four isolates). Six isolates could not be assigned to any formally described species of Phytophthora and are therefore described here as Phytophthora marrasii sp. nov. The ITS phylogeny places P. marrasii in a terminal clade basal to the sister taxa (P. foliorum, P. hibernalis, P. lateralis, and P. ramorum) of the clade 8c. In particular, P. marrasii is phylogenetically related to P. foliorum, a species from which it differs in 62 nucleotides in the ITS region. At the same time, it can easily be distinguished morphologically from P. foliorum mainly because of the low minimum temperature for growth, the bigger and persistent non-papillate sporangia, and smaller oogonia. Pathogenicity tests confirmed that all three Phytophthora species are pathogenic on globe artichokes, which represent a new host for these pathogens.

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Nam, Young-Ju, Sang-Keun Oh, Sun Ha Kim, Youn-Gi Moon, Weon-Dae Cho et Wan-Gyu Kim. « Phytophthora Foot Rot of Deltoid Synurus Caused by Phytophthora cryptogea ». Research in Plant Disease 28, n^o 3 (30 septembre 2022) : 162–65. http://dx.doi.org/10.5423/rpd.2022.28.3.162.

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Foot rot symptoms were repeatedly observed on plants of deltoid synurus (Synurus deltoides) growing in a field of the Wild Vegetable Research Institute located in Pyeongchang, Korea during disease surveys in July 2020 and June 2021. The symptoms appeared as wilting of the plant leaves, and the plant stems and petioles at or above the soil line turned dark and rotted. The incidence of diseased plants in the field was 5‒10%. Five isolates of Phytophthora sp. were obtained from lesions of the diseased plants and investigated for their morphological and molecular characteristics. All the isolates were identified as Phytophthora cryptogea based on the morphological and molecular characteristics. Three isolates of P. cryptogea were tested for pathogenicity on deltoid synurus plants using artificial inoculation. All the tested isolates caused foot rot symptoms on the inoculated plants. The symptoms were similar to those observed in plants from the field investigated. To our knowledge, this is the first report of P. cryptogea causing Phytophthora foot rot in deltoid synurus.

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