Abstract: Trichoderma is a biocontrol fungus that has been proved to have good control effect in the field on grape gray mold, tomato Fusarium wilt and melon anthrax. Most Trichoderma preparations on the market are wettable powders with conidia as the main component, which has the problem of short shelf life and dust pollution when used. In order to solve this bottleneck problem in the application of Trichoderma and improve its application value, this study focused on the industrial production of Trichoderma T4 as a water dispersible granule agent on the basis of the optimization of the laboratory flask high-yielding chlamydospore fermentation medium. With kieselguhr as carrier, 3% stabilizer CMC, 0.4% UV protectant ascorbic acid, 4% disintegrating agent soluble starch and 3.2% binder starch were selected for granulation by wet swaying granulation method, and 1×10⁸cfu/g Trichoderma T4 WDG was obtained to prevent and control gray mold in the field for the first time in the flowering period or the early stage of the disease. The application concentration was 300-500 times diluted, the application interval was 7 days, and a total of three times. The results showed that the best concentration was 300 times dilution, the control efficacy of tomato gray mold reached 71.85%, which was the same as that of 50% boscalid WDG 1000 times dilution.

Key words: Trichoderma, water dispersible granule, gray mold control