Abstract:Strain CanL30 of Bacillus velezensis was incubated in 10L,1ton and 10ton jar fermenters for characterization of bacterial growth and endospore development. A water wettable powder of CanL30 was formulated based on the endospores from the bacterial cultures,and the powder was evaluated for efficacy in control of Sclerotinia stem rot and blackleg of oilseed rape. The results showed that CanL30 could grow and form endospores in the fermenters. After incubation at 30℃ for 48 h in the 10L fermenter,for 36 h in the 1t fermenter and for 40 h in the 10t fermenter,the endospore formation rates were 74%,93% and 92%,respectively. In the 1t and 10t fermenters,the final bacterial yield reached 1×1010 cfu/mL and 3.3×109 cfu/mL,respectively. The resulting bacterial cultures were dried by heat spray,and a water wettable bacterial powder (1×1011 cfu/g) was prepared by amending the bacterial powder with related additives. The formulated powder conforms to the national standard of wettable powder pesticides regarding the thermal stability (54℃),suspension ability and wettability. The results of the bioactivity tests on agar medium showed that the powder had the antifungal activity against mycelial growth/sclerotial formation by S. sclerotiorum,and conidial germination of L. biglobosa. The result of the indoor biocontrol assay showed that the powder effectively suppressed infection by S. sclerotiorum and L. biglobosa on leaves of oilseed rape. The result of the field biocontrol assays in Tianmen City and Chibi City of Hubei Province showed that the powder suppressed Sclerotinia stem rot and blackleg by 55% and 42%,respectively,and the efficacy were not significantly different (P>0.05) from those in the treatment of the fungicide prochloraz,which suppressed Sclerotinia stem rot by 51% and blackleg by 37%. Compared to the control treatment,the application of the CanL30 powder significantly (P<0.05) increased the yield of seeds of oilseed rape by 14% in the Tianmen trial and 12% in Chibi trial. These results suggest that the water wettable powder of CanL30 can effectively suppress Sclerotinia stem rot and blackleg of oilseed rape,and meanwhile,it can enhance the seed yield of oilseed rape.