Isolation and Identification of Biocontrol Fungi against Tobacco Bacterial Wilt and Their Antagonistic Activity

In this study,the antagonistic fungal strains against tobacco bacterial wilt were isolated and identified,in order to provide some research basis for biocontrol of the disease.In total,116 fungal isolates were obtained from rhizosphere of tobacco by serial diluting isolation.Six strains(about 5.2%) with certain antagonistic activity against the growth of wilt pathogen Ralstonia solancearum were found through the disc diffusion assay.The antagonistic activities of the extracts from two strong active fungal strains,3F03 and 7F06,were confirmed by MIC assay.The results showed that the IC50 of 3F03 and 7F06 against R.solancearum were 361.96 μg/mL and 102.67 μg/mL,respectively.These two active strains were further identified as Aspergillus fumigatus and Neosartorya aureola based on their morphology and ITS rDNA analysis.