The registration of another fungicide with a different mode of action against powdery mildew is anticipated for the 2000 growing season. This fungicide will be recommended to be combined with chlorothalonil in this program. Consult with your county Extension agent for details. It is important to alternate fungicides with different modes of action to delay the development of resistant strains of the pathogen to newer fungicides. Disease occurs during cool periods.
Excellent resistance is available in some varieties.
Use resistant varieties when possible. Begin sprays as true leaves form. Repeat every 5 to 7 days. Do not cultivate after fungicide application. Occurs primarily in late summer.