Screening and identification of antagonistic strain against Phytophthora sojae.

[Objective] The paper was to screen the antagonistic strain against Phytophthora sojae with biocontrol potential,and provide basis for searching control measures and designing new control strategies against P.sojae.[Method] The rhizosphere soil of soybean was collected from three different places in Heilongjiang Province,and various soil microorganisms were isolated.Dual culture method was used to screen the microorganism with antagonistic effect against P.sojae.On this basis,the growth inhibition rate of the microorganism with stronger antagonistic effect against P.sojae was determined,and its control effect against P.sojae was also measured.[Result] A strain of bacterium with relatively good antagonistic effect was isolated from soil,and named as strain B048.Dual test showed that the growth inhibition rate of antagonistic bacterium B048 against P.sojae reached 97.5%.Antagonistic endurance tests showed that the width of inhibition zone was still 20.0 mm after dual culture with P.sojae for 21 d.In potting experiment,the control effect of B048 against P.sojae was 100%.The antagonistic bacterium was primarily identified to be Bacillus pumilus through morphology and 16S rDNA sequence analysis.[Conclusion] The antagonistic bacterium B048 had good prospect to be developed as the biocontrol bacterium against P.sojae.