How to Manage Pests

Pests in Gardens and Landscapes

Downy mildew—Peronospora pisi

Pea plants with downy mildew have white and purple cottony growth on the undersides of leaves. The tops of leaves have yellow blotches. Pods may have dark spots. Affected parts may be water soaked.



Downy mildew is caused by a soil or seedborne fungus. It is favored by low temperatures and moist conditions, especially fog. The best way to prevent downy mildew is to avoid the environmental conditions that favor it. Freely circulating air, allowing plants to dry between irrigations, and keeping leaves as dry as possible are good ways to limit the disease. Adjusting planting times may help in some areas. Always destroy infected crop debris and susceptible related weeds before planting a new crop. Some varieties may show resistance.

Cottony growth of downy mildew
Cottony growth of downy mildew

Yellow blotches on upper pea leaf surfaceYellow blotches on upper pea leaf surface

Statewide IPM Program, Agriculture and Natural Resources, University of California
All contents copyright © 2014 The Regents of the University of California. All rights reserved.

For noncommercial purposes only, any Web site may link directly to this page. FOR ALL OTHER USES or more information, read Legal Notices. Unfortunately, we cannot provide individual solutions to specific pest problems. See our Home page, or in the U.S., contact your local Cooperative Extension office for assistance.

Agriculture and Natural Resources, University of California

Accessibility   /PMG/GARDEN/VEGES/DISEASES/peadownymildew.html revised: April 25, 2014. Contact webmaster.