A correct detection and appropriate identification of causal pathogens associated with crop plants or seeds are considered to be the most important issue in designing the proper management plans for plant diseases. This study was designed to detect Phytophthora infestans inoculum from potato grown soil. A high detection rate of P.infestans was obtained from the naturally infested soil of potato fields. Naturally soils were firstly moistened in a plastic pots and then pre-incubated at ±18°C for 3 days, baiting with potato tuber slice for 24, 48, and 72 h. The baits were then thoroughly washed, flooded with 1015 ml of distilled water in Petri-dishes and incubated under continuous darkness in chamber ±18ºC. Sporangia started to emerge from the margins of potato tuber slice. They were easily observed under the stereomicroscope. Pure culture of the fungus was obtained by isolating from baited tubers on a Rye Agar medium. This is the first report of recovery of P. infestans from naturally infested potato growing soils using susceptible potato tuber (K. Bahar) as bait in India. All isolates were determined to be A2 mating type.
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Canaday C, Schmitthenner, A. 1982. Isolating Phytophthora megasperma f. sp. glycinea from soil with a baiting method that minimizes Pythium contamination. Soil Biol Biochem., 14: 67 68.
Davison E, Tay FCS. 2005. How many soil samples are needed to show that Phytophthora is absent from sites in the south-west of Western Australia? Australasian Plant Pathol., 34: 293297.
Erwin DC, Ribeiro OK. 1996. Phytophthora diseases worldwide. American Phytopathological Society (APS Press), St. Paul, Minnesota, USA.
Gallegly ME Hong C. 2008. Phytophthora: identifying species by morphology and DNA fingerprints. American Phytopathological Society (APS press), St. Paul, Minnesota, USA.
Haverkort AJ. 2008. Societal costs of late blight in potato and prospects of durable resistance through cisgenic modification. Potato Res., 51: 4757.
Ho HH. 1981. Synoptic Keys to the Species of Phytophthora. Mycologia, 73:705714.
Hua-Bo Zhuzdw, Xiao-Ming W. 2003. A new method of isolating Phytophthora sojae from soil. Mycosystema, 22: 142147.
Lacey J. 1965. The infectivity of soils containing Phytophthora infestans. Annals of Applied Biology. 56: 36380.
Lamour K, Kamoun S. 2009. Oomycete genetics and genomics: diversity, interactions, and research tools. John Wiley & Sons, Inc., Hoboken, New Jersey, USA.
Mohammadi A, Alizadeh A, Mirabolfathey M, Mofrad NN. 2008. Races of Phytophthora sojae in Iran. Pak J Biol Sci.,11: 302 305.
OBrien PA, Williams N, Hardy GES. 2009. Detecting Phytophthora. Critical Reviews in Microbiology, 35: 169181.
Singh, B.P. and Bhattacharyya, S.K. (1995). Field resistance to late blight in four Indian potato cultivars. Potato Research. 38: 171- 178.
Ranjbaran M, Alizadeh A, Safaie N. 2006. Genetic diversity of Iranian populations of Phytophthora nicotianae using ISSR and RAPD markers. Iranian Journal of Plant Pathology, 42: 619 638.
Reeser PW, Sutton W, Hansen EM, Remigi P, Adams GC. 2011. Phytophthora species in forest streams in Oregon and Alaska. Mycologia, 103: 2235.
Tsao PH. 1983. Factors affecting isolation and quantitation of Phytophthora from soil. In Erwin DC, Bartnicky Garcia S, Tsao PH (eds.). Phytophthora its Biology, Taxonomy, Ecology, and Pathology. St. Paul, Minnesota: American Phytopathological Society (APS Press), pp. 219236.
Wu X, Zhou B, Zhao J, Guo N, Zhang B, Yang F, Chen S, Gai J, Xing H. 2011. Identification of quantitative trait loci for partial resistance to Phytophthora sojae in soybean. Plant Breed, 130:144149. www.worldseed.org, last accessed in November 2012.
Yamak F, Peever TL, Grove GG, Boal RJ. 2002. Occurrence and identification of Phytophthora spp. pathogenic to pear fruit in irrigation water in the Wenatchee River Valley of Washington state. Phytopathology, 92:12101217.