Powdery Mildew

Powdery mildew looks exactly like its name suggests.

Leaves develop a white or gray powdery coating.

Common Hosts

It often appears on:

Early symptoms include:

Severe infections can cause:

Powdery mildew often thrives when:

Unlike many fungal diseases, it does not require constantly wet leaves.

Give plants proper spacing.

Avoid dense overcrowding.

Resistance can make a major difference, especially for squash and cucumbers.

Do not remove so much foliage that the plant is severely weakened.

Focus on heavily infected material.

Water at the root zone.

Healthy, unstressed plants tolerate disease better.

If needed, use a product labeled for the specific crop and disease.

Timing matters.

Fungicides usually work best before infection becomes severe.

By late summer, a little powdery mildew may be cosmetic.

Treat based on whether it is actually shortening the useful life of the plant.