关键词: 花生褐斑病, 化学杀菌剂, 抗菌脂肽, 毒力测定, 复配, 生物防治

Abstract: Peanut brown spot is a leaf disease caused by Cercospora arachidicola （C.arachidicola）. To explore the inhibitory activity of the mixture of biocontrol metabolites and chemical fungicides，the antagonistic effect of biocontrol bacterium SJ1606 on C. arachidicola was tested by confrontation culture method，and then the inhibitory activity of antimicrobial lipopeptides，six chemical fungicides and the mixture of lipopeptides and chemical fungicides were determined by mycelial growth rate method. The results showed that the antagonistic effect of SJ1606 on C. arachidicola was significant，and the inhibition rate was 71. 8%. The EC50 of crude antimicrobial lipopeptide extract was 1 149. 89 mg/L. Carbendazim was the best among the six chemical fungicides，with EC50 of 1. 53 mg/L. The EC50 of prochloraz， tebuconazole，propiconazole and pyraclostrobin were 1. 74，2. 15，4. 50 and 5. 40 mg/L respectively. The antifungal activity of difenoc onazole was the weakest，with EC50 of 13. 14 mg/L. The mixture of lipopeptides and chemical fungicides showed a synergistic effect in a certain proportion. The mixture of lipopeptides and propiconazole showed a synergistic effect on the inhibitory activity of C. arachidicola，and the toxicity ratio was up to 1. 39 when the volume ratio was 1∶9. The other five chemical fungicides mixed with lipopeptide had both synergistic and antagonistic effects. When the ratio of carbendazim to lipopeptide was 2∶8，the highest toxicity ratio was 1. 35. In summary，the metabolites of biocontrol bacteria and the tested chemical fungicides showed good inhibitory activity against C. arachidicola， and the mixture of propiconazole and lipopeptide had better inhibitory activity against C. arachidicola. This study will provide technical support for the utilization of biocontrol bacteria SJ1606 and the scientific use of fungicides.

Key words: peanut brown spot disease, chemical fungicides, antimicrobial lipopeptide, virulence assay, combination；biological control