Composition and virulence variation of the pathogen of wheat sharp eyespot from Henan Province

To make sure of composition and virulence variation of the pathogen of wheat sharp eyespot from Henan Province,157 Rhizoctonia strains were isolated from 13 districts in Henan in 2008 and 2009.All of the isolates were binucleate Rhizoctonia strains(BNR) identified by the nuclear staining.156 isolates were belonged to the binucleate Rhizoctonia AG-D anastomosis group and 1 was the AG-BO group through hyphal anastomosis reaction and rDNA-ITS sequences analysis.The virulence of 113 isolates were tested in greenhouse on 3 wheat cultivars such as Ji 5385,Shan 229 and Yumai 49.The virulence of Rhizoctonia isolates showed significant difference,and it could be divided into three pathotypes:the highly,moderately and weakly aggressive isolates,accounting for 58.40%,35.40% and 6.19%,respectively.The results indicated that the virulence of isolates had certain difference among the 13 different regions,the isolates from Hebi,Zhoukou and Luohe regeins showed strong virulence,whereas that from Xinyang region showed weak virulence.The virulence of Rhizoctonia isolates on 3 wheat cultivars also had significant difference,the strong virulence on Shan 229 and weak virulence on Ji 5385.