What Is It?

What Is It? | Facts in Depth | For the Professional Diagnostician
Cucurbit Diseases | Phytophthora Blight

Phytophthora Blight

Foliage and Roots:

  • Damping off
  • Watery, soft root rot
  • Rapid wilting following heavy rains
  • Watersoaked, brown lesions on stem and vines
  • Watersoaked, chlorotic and brown lesions on leaves

CukePhytoph3 50 Quality PhytophPumpkinLeaves4 50 Quality PhytophPumpkinLeaves1 50 Quality
Foliar symptoms on cucumber plants (left) and pumpkin leaves (middle and right).


  • Watersoaked, slightly sunken and discolored areas on fruit
  • White-tan velvety growth on fruits

CukePhytoph1 50 Quality Phytoph pumpkin 50 Quality Phytoph winter squash 50 Quality
Symptoms on cucumber fruit (left), pumpkin (middle), and winter squash (right).

Favorable Environmental Conditions

  • Warm soils (68-86° F)
  • Wet, waterlogged soils
  • Warm and rainy conditions

Often Confused With

  • Damping off
  • Anthracnose
  • Bacterial wilt
  • Fusarium wilt
  • Bacterial fruit blotch

Scouting Notes

  • Scout poorly-drained fields for this disease.
  • Look in low lying areas and areas prone to flooding.
  • Scout following heavy rains.

zucchiniPhytoph 50 Quality
Symptoms of wilting caused by Phytophthora blight in a zucchini field.