Determination of the Pathogenicity of Phytophthora Parasitica and Identification of the Difference in Resistant Tobacco Varieties against Black Shank in Enshi

In order to take effective measures to control tobacco black shank in Enshi, the virulence of Phytophthora nicotianae was analyzed by using the method of the wounded stalk inoculation with mycelia. Strains could be classified into three virulence pathotypes (I, Ⅱ and Ⅲ) by cluster analysis based on AUDPC (Area under Disease Progress Curve) values of three cultivars, K326, Hongda, and Yunyan202. And the three pathotypes showed atypical pathogenic characteristics. 7 resistant tobacco varieties showed different resistance to different pathotypes of Phytophthora nicotianae, and Gexin 3# showed good resistance to all three kinds of pathogenic strains.