Powdery mildew—Erysiphe polygoni
Powdery mildew usually appears first as yellow spots on the upper leaf surface of older leaves. The upper
surface of leaves become covered with a white powdery growth on the top sides. The leaves may also curl
and dry out. Pea pods may get brownish spots on them.
Identification | Life
Powdery mildew is favored by warm, dry days and cool, damp nights. In most cases, planting resistant
varieties or avoiding the most susceptible varieties and following good cultural practices will adequately
control powdery mildew. Plant in unshaded areas as much as possible. Provide enough water and avoid excess
fertilizer. Because spores cannot germinate when there is free moisture and may be killed, plantings with
overhead sprinkler systems or frequent water sprays may have reduced incidence of powdery mildew. Where
conditions are most favorable for mildew, dust with sulfur. Compost or bury infected residues to destroy
For more information, see the Powdery
Mildew Pest Note.
pod infected with powdery mildew