Usually a spring disease that will let up in higher temperatures or lower humidities. Severe defoliation following irregular greenish-black, watersoaked spots on older leaves. In humid weather, there may be a white, downy growth on spots. May spread from infected potato plants. Bordeaux mixture will treat.
White spots appear on surface of older leaves, enlarging and yellowing.
With humidity, patches become velvety and olive-green. Common in Atlantic, Central states, and Southern Plains states. Most severe in rainy seasons, crowded patches. Usually not seen before mid-July. Older leaves have many, small, watersoaked spots, usually 1-2mm diameter.