Biological control of gray mold [Botrytis cinerea] on tomato [Lycopersicon esculentum] by duct dusting method of Bacillus subtilis

In 2003 and 2004, the control effects on gray mold of tomato and valid supplements of duct dusting with the Bacillus subtilis wettable powder (following BS powder) was investigated in six fields in Ibaraki. As a result, duct dusting with BS powder was highly effective for the control of gray mold in the three fields. Moreover, the frequency of use of chemical fungicide was decreased. In the others, the control effect was not clear. However, BS powder was scattered all over the greenhouse using duct dusting and adhered on tomato leaves. For control of gray mold disease by duct dusting with BS powder effectively, it was important to start before the disease occurred to dust early with chemical fungicide if it occurred to remove old or diseased regions and to control humidity in the greenhouse thoroughly.