Abstract: Bacillus amyloliquefaciens X17, a plant endophyte, was used as raw material to develop its wettable powder. After carefully screening the influential factors including carrier, dispersing agent, wetting agent, stabilizer, and protective agent, the optimal formulation was determined to be 10% diatomite as filler, 4% CMC-Na as dispersing agent, 6% SDS as wetting agent, 2% methylcellulose as stabilizer, 0.1% dextrin as UV protective agent. The spore content of the wettable powder with a suspension rate of 78% and a dispersing time of 35 s, reached 2.0×10¹⁰ cfu/g (pH 7.0) in the quality evaluation investigation. Pot experiment showed that the protective effects of the diluted 500 times solutions of the prepared wettable powder and initial fermented powder were 80.59% and 68.82%, respectively. Importantly, its control efficacy against Botrytis gray mold of kiwifruit was superior to that of the initial fermented powder.

Key words: Bacillus amyloliquefaciens, Botrytis cinerea, wettable powder, biocontrol effect