Abstract

Powdery mildew of strawberry is a major limitation in most fruit production areas in the world. The effects of the Bacillus strain TS02 on bio-controlling powdery mildew of strawberry were tested in the fields. The results indicated that the fermented liquid of TS02 above 3×10⁷ CFU/ml live bacteria concentration could control the disease of strawberry powdery mildew. The best effect was 52.23% with 3×10⁹ CFU/ml live bacteria. There were 48.98, 34.89 and 24.63% bio-control effects, respectively with the bacteria fermented liquid, pure live bacteria and filtrated bacteria fermented liquid on strawberry powdery mildew, which showed the corporate results of live bacteria and secretion of bacteria. The bio-control mechanism was primary searched in laboratory with the leavesin vitro, and there was 100% growth inhibition of TS02 on Sphaerotheca macularis at 5 days after inoculation of powdery mildew pathogen. TS02 might inhibit the location of pathogen on the surface of leaves. TS02 also formed a monophyletic group with the species of the Bacillus thuringiensis complex group in the 16SrDNA sequence analysis, and shared similarity values of 99.9% with the B. thuringiensis type strains in the sequence analysis. It has a 6 bp difference from the most homologous strain B. thuringiensis AF290545.

Key words: Strawberry, powdery mildew, bio-control, Bacillus strain, 16S rDNA.