A plant disease that causes yellow, pale green, or purple-tinted leaf spots and produces a fuzzy growth on the undersides of leaves, especially during cool, humid conditions.
Downy mildew usually appears first as discolored patches on the upper surface of leaves. As the disease develops, a gray, white, or purplish fuzzy growth often becomes visible underneath the leaf.
The disease spreads most readily when foliage remains wet and humidity stays high for extended periods. Once established, it can move quickly through susceptible plants, reducing vigor and damaging crops.
Many vegetables, herbs, ornamentals, and fruiting plants can be affected by downy mildew under favorable conditions.
Downy mildew can weaken plants by reducing healthy leaf area and interfering with normal growth. Because the disease spreads rapidly in cool, moist environments, early identification and prevention are often more effective than trying to manage severe infections later.