Abstract: 【Objective】The objective of this study is to evaluate the application potential of microbial volatile compound benzothiazole on Botrytis cinerea, and to provide a valuable information for further exploitation and utilization.【Method】The sensitivity of 73 B. cinerea isolates in Shandong Province to benzothiazole was measured by mycelium growth rate of sealed dishes method. The sensitivity differences among different regions and phynotypes of B. cinerea isolates (resistant and sensitive to carbendazim, procymidone, pyrimethanil or boscalid: Car^R, Car^S, Prc^R, Prc^S, Pyr^R, Pyr^S, Bos^R, Bos^S) were compared. The combination efficiencies on B. cinerea of benzothiazole with carbendazim or boscalid were determined. The protective and curative effect of benzothiazole against cucumber gray mold, and the effects of benzothiazole at different doses and fumigation times on the pathogenicity of B. cinerea were determined on detached cucumber leaves. The mycelial morphology of B. cinerea treated by benzothiazole was observed with scanning electron microscope (SEM). 【Result】 All the tested B. cinerea isolates were sensitive to benzothiazole, range of EC₅₀ from 0.38 to 1.08 μL·L^-1, with a mean EC₅₀ value at 0.62 μL·L^-1. There was no sensitivity difference among different regions. All the phynotypes of isolates (Car^R, Car^S, Prc^R, Prc^S, Pyr^R, Pyr^S, Bos^R, Bos^S) were sensitive to benzothiazole, suggesting that there was no cross-resistance between these fungicides and benzothiazole. In the range of 0.1-3 μL·L^-1 of benzothiazole, mycelia were more sensitive than spores to benzothiazole. The inhibition rate of 2 μL·L^-1 benzothiazole for mycelial growth, germ tube elongation and spore germination was 86.12%, 55.15%, and 19.30%, respectively. It is suggested that the sensitivities of different growth stages of B. cinerea to benzothiazole were different. There was no synergism when benzothiazole combined with carbendazim, and which active ingredient performed the main antifungal activity depended on the concentration and proportion of each compound in the mixture. The synergism of benzothiazole combined with boscalid was obvious, but the exact field practical application method, efficacy and mechanism of synergism remains to be further investigated. The result of in vitro leaf test showed that benzothiazole had protective and curative effect against cucumber gray mold, and the curative effect was superior to the protective effect. The curative effect of 2 μL·L^-1 benzothiazole against cucumber gray mold was 91.01%, which was higher than the control fungicide boscalid at 300 mg·L^-1 (78.90%) and the protective effect (48.25%). Benzothiazole could significantly reduce the pathogenicity of B. cinerea mycelia on detached cucumber leaves, and the inhibition level was positively correlated with the concentration of benzothiazole. The results of SEM images indicated that benzothiazole caused large alterations in mycelial morphology of B. cinerea, showing a wrinkled surface and anomalous branching of the terminal mycelia. 【Conclusion】Benzothiazole has high toxicity to B. cinerea in different regions of Shandong Province, which indicates that benzothiazole could be applied as a fumigant for controlling gray mold.

Key words: volatile compounds')">