Abstract:In order to identify the pathogens of walnut blight in Sichuan Basin Area, the pathogens was isolated by using tissue isolation method, and the pathogenicity was tested using Koch's postulates. The pathogen was identified based on morphological characteristics and sequence analysis of 16S rDNA, and the resistance of 18 cultivars (clones) of Juglans regia was evaluated through field infection using the isolated strain. The results showed that the morphology of isolated pathogen were similar with Xanthomonas, which sequence of 16S rDNA showed 99% similarity with X. arboricola (GenBank No. KP340804.1). Therefore, X. arboricola was identified as the pathogen caused the walnut blight in Sichuan basin area. The incidence and disease index of 18 walnut cultivars (clones) were ranged from 35.07% to 78.57%, and 17.71% to 51.96%, with the coefficient of variation of 17.62% and 28.78%, respectively. Based on the resistance evaluation, five highly resistance cultivars (clones) were selected. Therefore, these would provide basis for pathogenesis mechanism of walnut blight and resistance breeding.