Abstract:[Background] Single biocontrol agents have unstable and poor lasting biocontrol effects. It is one of the effective ways to control plant diseases to develop composite microbial agents for biocontrol by studying the synergistic effect of different functional microorganisms. [Objective] To explore the biocontrol effects of different functional microbial combinations on rice blast, and develop an efficient composite microbial agent. [Methods] The biocontrol effects of Streptomyces combined with bacteria on rice blast were studied by pot and field experiments. [Results] The combination of Streptomyces Ahn75 and Bacillus amyloliquefaciens CWJ2 had the best effect, which, combined with adjuvants, showed the potting control effects of 65.07% and 63.00% on rice blast in the leaves and panicles, respectively. The combination had significantly higher biocontrol effect than the single strain Ahn75 or CWJ2 and other combinations. Moreover, this composite microbial agent can promote the growth of rice plants, increasing the number of tillers and plant height in pots by 93.33% and 9.83%, respectively. Similarly, the results of field experiments showed that this composite microbial agent reduced the incidence of rice blast, with the maximum control effect of 52.16%, which was comparable to that (52.97%) of tricyclazole. In addition, the inhibition rates of Ahn75 and CWJ2 against 14 and 16 races of Magnaporthe oryzae were higher than 50%, indicating that the composite microbial agent possessed broad-spectrum resistance to rice blast. [Conclusion] The composite microbial agent (Ahn75+CWJ2) has a promising prospect in the control of rice blast and can be used in the development and application of biopesticides.
