Biocontrol of bacterium strain BSH-4 against cucumber sclerotial blight and its identification.

An antagonistic bacterium strain BSH-4 was isolated from rhizosphere soil of cucumber in the greenhouse.Dual culture test indicated that the strain was highly inhibitory to Sclerotinia sclerotiorum by making the mycelium swollen and curly,the protoplasm inside brown and concentrated,and the production of sclerotium delayed.Treat with fermentation broth of BSH-4,the disease control efficacy was 81.6% on detached leaves test,and 68.3% on pot trials.And the recovering rate was attained to 74.4% when sclerotial blight infected stems of cucumber was treated in the field.All the efficacies of BSH-4 broth excelled that of dimethachlon fungicide.The fermentation broth of BSH-4 had no impact on seed germination rate,but also promoted the growth of cucumber seedling.Identification by morphological observation,physiological and biochemical determinations,and 16S rDNA sequences analysis showed that the strain was belonged to Bacillus pumilus.