Powdery mildew

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A.M. Varela, icipe
Is this a Minor Pest?
Minor Pest Title

Powdery mildew (Erysiphe polygoni)

Minor Pest Description

It is characterised by a white powdery growth on the leaves, stems and pods. The initial symptoms consist of tiny slightly discoloured spots on the upper surface of leaves. Theses spots enlarge and become covered with powdery fungal growth. The tissue beneath affected areas may turn purple and later brown. If infection is severe, affected plants turn brown and die. Affected seeds become brown. Water stress accelerates mildew development. Warm days and cool nights favour disease development. The fungus is seed-borne.


Minor Pest What to do.
  • Use certified disease-free seeds.
  • Treat own seeds by soaking for 30 minutes in 122 °F / 50 °C.
  • Plant resistant varieties, if available.
  • Practice crop rotation with non-legumes.
  • Plough under crop residues after harvest.
  • Spray with sulphur products, where local administration permits.
Minor Pest Position
Minor Pest Firstcontent
Pest Type
Host Plants