downy mildew

Downy mildew is a plant disease caused by water molds that appears as fuzzy, grayish-white or purplish growth on the undersides of leaves.

It thrives in cool, humid conditions and affects a wide range of crops including grapes, cucumbers, lettuce, and spinach.

Unlike powdery mildew, which stays on leaf surfaces, downy mildew penetrates plant tissue and can cause significant crop damage.

The wet spring led to an outbreak of downy mildew in the vineyard.