What Is It?

What Is It? | Facts in Depth | For the Professional Diagnostician
Cucurbit Diseases | Cucurbit Downy Mildew

Cucurbit Downy Mildew


  • Disease begins as small chlorotic spots on leaves
  • Yellow to olive, scattered lesions on topsides of leaves
  • Lesions often angular
  • White to gray-purple, fuzzy growth on underside of lesions

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Favorable Environmental Conditions

  • High humidity
  • Long periods of leaf wetness caused by dew or rain
  • Cool temperatures (59-68┬░ F)

Often Confused With

  • Angular leaf spot
  • Cercospora leaf spot
  • Powdery Mildew

Scouting Notes

  • Scout after periods of high humidity or frequent rain events
  • Scout in field areas prone to dew
  • Check the undersides of leaves and leaves located within the canopy (increased humidity)

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