Identification of the Pathogen from Cassava Brown Leaf Spot and Its Biological Characteristics
Brown Leaf Spot is the most serious leaf fungous disease in the cassava plantations of China.In our research,several separation and inoculation methods were applied,pathogenicity test was finished and the pathogen was isolated,morphlogical identification and ITS sequence analysis indicated the pathogen was Passalora henningsii.Four methods(light,hyphae-breaking,UV and hyphae broken-UV)were compared for their inducing capability in producing conidia from P.henningsii.The results showed large number of conidia could obtain by hyphae broken-UV method,and the best condition was Malt-cassava leaves medium,28 ℃,pH 6.0 ～7.0,continuous UV induction,25 mL/plate,14~21 d.The biological characteristics study of strain CPHHN02 showed CA medium,26～28 ℃,pH 6.0,continuous dark,D-glucose,D-mannitol,D-lactose and tryptone were the best culture condition.The optimal temperature for macroconidia germination was 26 ℃ and the lethal temperature was 60 ℃ for 10 min.