Study on Differentiation in Pathogenicity of Sclerotinia sclerotiorumof Sunflowers from Different Regions

In order to indicate the pathogenicity existed or not in the strains of Sclerotinia sclerotiorumtwenty strains of S.sclerotiorumisolated from sunflowers in different regions of Inner Mongolia and Heilongjiang province were tested for their pathogenicity with Longshikui No.3as host using the inoculation method of placing the mycelial plugs on the leaves in vitro.The results showed that sixteen strains of S.sclerotiorumcould infect the leaves of sunflowers after inoculated 72hours except for the other four strains,but the lesion sizes ranged from 1.00to 80.00mm in different strains.It indicated that the differentiation of pathogenicity among the strains of S.sclerotiorumin the test was existed,and the differentiation of pathogenicity might not be related to geographic distribution.