Abstract: ObjectiveIn order to provide a basis for disease-resistant breeding and integrated management of bacteri-al fruit blotch, suspected pathogen causing melon bacterial fruit blotch was isolated and identified. MethodSuspected leaves and fruits samples were collected from Nanning(No.WM0922) and Hezhou(No.XD0611),and pathogen was isolated and purified from samples,then identified based on pathogenicity test,colony morphology and cultivate characteristics, physiological and biochemical characteristics and 16S rDNA sequence analysis . ResultResults showed that , five germs were isolated from suspected leaves(No.WM0922),and three of which(No.WM0922-2,WM0922-3,WM0922-4) were pathogenic. Eight germs were isolated from suspected fruits (No.XD0611),four of which (No.XD0611-5,XD0611-6、XD0611-7,XD0611-8) were pathogenic. Two representative germs WM0922-3 and XD0611-7 were selected for follow-up test,and the test result showed that they could infect gourd leaves,and were identified as Gram-negative bacterium,with same culture characters,physiology and biochemistry,and their 16S rDNA sequences shared more than 99%similarily with that of Acidororax citrulli. ConclusionThe pathogen causing melon bacterial fruit blotch is identified as A. avenae subsp. citrulli.