Biological characteristics of pathogenic bacteria causing banana leaf spot disease

ObjectiveThe biological characteristics of Corynespora cassiicola(Berk & Curt)Wei,a pathogenic bacteria causing corynespora leaf spot of banana were studied to provide basis for comprehensive control of it.MethodBanana leaves with corynespora leaf spot in Yunnan banana planting areas were collected.Conventional tissue separation was applied to isolate monospore from pathogenic bacteria,and morphological characteristics and the pathogenicity of the pathogenic bacteria were investigated.Biological characteristics of the pathogenic bacteria were detected by plating meth-od.ResultPotato dextrose agar(PDA)was the optimal medium for hyphal growth.The optimum carbon sources were lactose and mannitol,the optimum nitrogen source was peptone.The suitable temperature ranged between 25-35℃,the optimal one was 28℃.The pathogenic bacteria could grow in pH 6-8,and the most suitable pH was 7.0.Light had certain effects on hyphal growth,and hypha grew at the fastest speed in dark.Corn meal agar(CMA)medium was the optimal cul-ture medium for sporulation;alternating light and dark could promote sporulation.Lethal temperature and time for hypha of the pathogenic bacteria were 58℃for 15 min,and 51℃for 5 min for conidia.ConclusionThe temperature range for hypha growth of C.cassiicola is wide,and high temperature is more suitable for its growth.But the pH range is narrow. The key factor to sporulation is nutrient components of the media and light condition.