Abstract: ObjectivePathogenic bacteria causing mildew disease on Kyoho grape berries surface in Nanning, Guangxi were isolated and identified to provide reference for controlling mildew disease.MethodThe morbidity and symptoms of mildew disease on grape berries was investigated by five-points sampling method in the infected vineyard. 100 single mildew spots with typical morphology characteristics were collected randomly.The spores of pathogenic strains were isolated and purified.Then their pathogenicities after forming mildew were tested by Koch's rule,and the pathogenic bacteria were identified by morphological observation and molecular methods.ResultIn the surveyed vineyard,the mor-bidity of mildew disease for winter berries in 2015,summer berries in 2016 and winter berries in 2016 were 86.00%、87.32% and 89.33%,and the corresponding disease index reached 52.80,62.40 and 58.27. From the 100 mildew sam-ples,the selected strains shared similar colony morphological characteristics,and pathogenicities after forming mildew of eight randomly selected strains were identified.According to morphological observation and molecular biology identifica-tion results,the isolated pathogenic bacteria was identified as Penicillium citrinum.ConclusionP.citrinum is one of the-pathogenic bacteria that causes mildew disease on Kyoho grape berries surface in Nanning,Guangxi.Comprehensive con-trol should be enhanced through cultivation techniques at present.