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.

Identification

Solutions

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
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