Abstract: Black plum (Prunus americana) canker is a serious disease occurring in recent years in black plum plantation in Zhejiang Province. It mainly infects currentyear shoots， perennial branches and trunks， causing the branches withered and the whole plant died， and finally destroyed the whole black plum orchard. In this study， we collected the typical symptom samples of this disease， isolated and purified the pathogen， and then the pathogenicity determination results showed that the pathogen causing black pulm canker was a kind of bacteria. The pathogenic bacteria was identified as Xanthomonas arboricola pv. Pruni(smith) Vauterin et al. based on the bacteria cell morphology， cultural characteristics， physiological and biochemical characteristics， analysis of fatty acid methylesters (FAME) and 16S rDNA gene sequence．

Key words:  pathogen identification, black plum canker, fatty acid methyl esters, 16S rDNA, Xanthomonas arboricola pv. Pruni