Soybean Diseases in Ohio

Downy Mildew

• Symptoms
  • pale green to yellow spots on upper surface of young leaves
  • lesions turn grayish-brown to dark brown with yellowish green margins
  • fuzzy purple growth on lesions on the lower leaf surface
  • premature leaf drop of severly infected leaves
  • crusty white mycelium on seed coats
• Environment
  • high humidity & cool temperatures (68 -72°F)
  • young leaves very susceptible
• Survival
  • overwinters in leaf residue and on seed coats
• Management
  • seed treatment
  • plowdown soybean residue
  • crop rotation
• Scouting