Abstract:  Xanthomonas axonopodis pv. citri (Xac) is the phytopathogen responsible for bacterial citrus canker. Twenty two strains of Xanthomonas axonopodis pv. citri (Xac)) were isolated from different Citrus growing areas of Marathwada region of Maharashtra state. Morphological, biochemical and pathogenicity tests were carried out to identify, characterize and determine the strains of bacteria responsible for Citrus canker. All the 22 bacterial isolates produced mucoidal colonies on Yeast extract-dextrose-CaCO3 (YDC) agar media selective media for Xanthomonas. Biochemical tests of the 22 bacterial isolates indicated that all the isolates were Gram-negative short rods, positive for Hydrolysis of Aesculin, Gelatin liquefaction, Starch hydrolyse, Milk Hydrolysis Tween80 lipolysis, Catalase, H2S production and Urease production , Oxidase test were  showed variation negative  weakely positive and positive . All isolates produced acid from Glucose,,Fructose where all isolates were fail to produced acid from Manose. The results of the study suggest variation in the pathogenic nature of these isolates 06 were highly virulent, 11 were moderately virulent and 05 were less virulent from different agro climatic zones of Marathwada region of Maharashtra state .

Key Words: Xanthomonas axonopodis pv. citri (Xac), Citrus canker, Citrus, Biochemical, pathogenicity, Pathogenic variability.

| DOI: 10.17148/IARJSET.2023.105114