Pathogenicity of Alternaria longipes in Typical Mountain Climate Regions of Guizhou

In order to understand the pathogenicity differentiation of A.longipes in typical climate regions of Guizhou,the pathogenicity of 25 pathogens of A.longipes,which were isolated from five typical mountain regions of Guizhou in 2011,was measured by using spore suspension to inoculate the detached leaves of tobacco.The results indicated that all pathogens showed pathogenicity to some extent.According to the average disease index post inoculation,the pathogenicity differentiation was found and the pathogenicity of all isolates could be classified into four categories(strong,relative,moderate,weak).The different strains had obvious differences on leaves of tobacco cultivar K325.Two strains showed strong virulent,but two strains were stronger than those.While ten strains showed moderate virulent and eight those were weak virulent,the majority strains showed moderate virulent.For all tested strains,pathogenicity differentiation existed the obvious difference in different mountain climate region,even in the same region.