Biological control of Botrytis mali on apple fruit by use of Bacillus bacteria, isolated from the rhizosphere of wheat

Bacillus pumilus (B19), B. subtilis (1J), B. crerus (B16), B. subtilis (B11) and B. cereus (B17), isolated from the rhizosphere of wheat, were tested for control of gray mold of apple caused by Botrytis mali. Dual culture, cell free metabolite and volatile tests showed that all five isolates of Bacillus spp. inhibited growth of the pathogen. Inhibition varied from 13.6 to 74% in the dual culture tests; 12.3 to 87% in the cell free metabolite tests; and 11 to 53% in the volatile tests. Five isolates of Bacillus spp. reduced B. mali lesion diameter from 7.2 to 32.2 mm compared with 41.6 to 51.4 mm in controls at 4°C. At 20°C the lesion diameters were from 7 to 24.9 mm for antagonistic treatments and from 46.2 to 46.6 mm for the control treatment after 15 days.