Where disease is present or anticipated, do not work in fields when plant surfaces are wet. Apply one of the following beginning shortly after transplanting and repeat every 7 days. To prevent rots in green wrapped tomatoes, avoid washing freshly harvested fruit in cold water. Maintain water temperature in flumes and tanks near fruit temperature to prevent movement of bacteria into the stem end of the fruit. The use of chlorothalonil and Quadris for control of other foliar diseases on tomatoes should provide control of powdery mildew.
Infection generally occurs around flowering.
Sprays should be initiated when the first flowers appear and be repeated once 7 days later. High soil moisture and temperature favor disease development. Long crop rotations with corn and small grains help reduce disease incidence. Fusarium and Verticillium Wilts. Use resistant varieties.