Abstract: Transplanting seedlings with pathogen results in the spread of pepper blight. In order to effectively use biocontrol bacterium to prevent and control pepper blight at seedling stage,the efficacy of Bacillus velezensis LYK10 and Bacillus cereus QTK2 against pepper blight of seedling by soaking seed were tested by point plate seedling with biocontrol bacteria. The synergies of mixed biocontrol bacterium and biocontrol bacteria combined chemical fungicide were mensurated. The results showed that LYK10 and QTK2 could delay the occurrence time of pepper seedling disease, and the control efficiency of pepper seedling disease was respectively 30.55% and 33.33%, and the emergence rate was increased by 1.39% and 2.78% in turn. The both bacterium had antagonistic effects on Phytophthora capsici., and also induced the changes of CAT and PPO enzyme activity in pepper plants. The efficiency of the two mixed bacterium at equal concentration improved from 27.78% to 42.45% compared with the two single bacteria treatments. The efficiency of the mixture of LYK10 and dienomorph with the consistence of 5.0×10⁷cfu/mL+300 µg/mL and 5.0×10⁶cfu/mL+150 µg/mL respectively were 48.15% and 38.89%. The control effect of high concentration bacterial-drug treatment was higher than the treatments of 10⁸ cfu/mL LYK10 and 300 g/mL dienomorph. The control effect of low concentration bacterial-drug treatment was higher than LYK10 and comparable to dienomorph. The results can provide data to support for the research on biological control to pepper blight and effective utilization of biocontrol bacterium.

Key words: Phytophthora capsici, seedling stage, Bacillus sp., mixed bacterium, bacterial-drug mixture