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Title: Geographic distribution of Rhizoctonia and Pythium species in soils throughout eastern Washington.

item Paulitz, Timothy
item Okubara, Patricia

Submitted to: Joint Meeting of the American Phytopathological Society and Society of Nematology
Publication Type: Abstract Only
Publication Acceptance Date: 7/28/2007
Publication Date: 7/28/2007
Citation: Schroeder, K.L., Paulitz, T.C., Okubara, P.A. 2007. Geographic distribution of Rhizoctonia and Pythium species in soils throughout eastern Washington.. Joint Meeting of the ADSA, AMSA, ASAS and PSA.

Interpretive Summary:

Technical Abstract: Rhizoctonia and Pythium species cause substantial reductions in yield in eastern Washington. Both organisms are common in agricultural soils; however, the specific species or anastomosis group (AG) present can vary from site to site. Due to a wide range in virulence among these different groups, the impact of these pathogens could vary greatly depending on the species composition at a particular site. Soils were collected from 21 wheat variety testing sites and 29 grower fields throughout eastern Washington. DNA was extracted from these soils using a commercial kit in combination with a pressure cycling treatment. Specific primers were used in conjunction with real-time PCR to detect and quantify R. solani AG-8 and AG-2-1, R. oryzae, P. irregulare groups I and IV, and P. ultimum. R. solani AG-8 was found most frequently in areas of low rainfall (<350 mm/year) while R. oryzae and P. irregulare groups I and IV were prevalent in higher rainfall zones (>350 mm/year). The presence of P. ultimum was sporadic and occurred only in the higher rainfall zone or irrigated plots, while R. solani AG-2-1 was primarily found in fields with a history of mustard or canola cultivation. The use of these robust tools for quantification of soilborne pathogens can greatly improve our understanding of the diversity in the soil and potential correlations with plant damage and yield.