Red Grape Powdery Mildew Antagonist Microbial Screening And Preliminary Study The Field Application

Red globe have a poor disease resistance, especially to pathogenic fungal disease. In recent years, powdery mildew of red globe grape occurred frequently in every grape-producing region,and its incidence is increasing year by year,which directly reduce the quality and yield of red globe.This study aimed at separating and screening antagonistic bacterias with great activity on the powdery mildew of red globe grape from the root soil, collected from red globe growi-ng areas, and optimizing the fermentation conditions and medium, and last used in the field disease control test.Antagonistic strains SZ3and LT6isolated from the soil sample which collected from seven red globe growing gardens, heated at80℃for15min, with strong inhibition effect on the powdery mildew of red globe. Test of biological antagonistic activity showed that antagon-istic strains SZ3and LT6fermentation filtrate had strong inhibitive effect on three pathogenic fungus such as downy mildew,white-rot disease and anthraxAccording to cultural morphology,physiological and biochemical character of the SZ3and LT6strains. Both those two strains identified as Bacillus subtilis.Make SZ3and LT6cross a crossed, single and mixed bacteria liquid fermentation metho-d for culture, and then measured the value of A660and antibacterial ability.The mixed ferme-ntation of medium and culture conditions is optimized by single factor and orthogonal design method. The best fermentation conditions was:initial pH7.0, fermentation temperature30℃, rotation180r/min, fermentation time36h. The best medium was glucose1%+cornmeal3%, beef extract1%+soybean flour3%, ZnSO40.1%and CaCl20.1%.The field experiment results showed that mixed fermentation has meaningful control eff-icacy against powdery mildew of red globe.used with BFA bacterial manure, mixed ferment-ation showed better effect. And compared with control group, the average chlorophyll con-tent of leaves, Fruit-grain weight better than chemical control groups Obviously.