Cucurbit Scab

Cucumber ScabPhoto Credit: Margaret Tuttle McGrath, Cornell University

Pale green, water-soaked areas on cucumber leaves are a first symptom of this fungal disease. Melons, summer squash, winter squash, and pumpkins can also develop this disease, although watermelons, butternut and acorn squash have good natural resistance. Infected leaf areas often have an angular shape; they gradually turn from pale green to white. The disease also manifests as small spots on the skin of fruits. These spots often lead to rot as the areas become infected with secondary diseases such as bacterial blight. The fungus overwinters in seeds and plant debris.

Prevention and Control

  • Plant disease-free seed.
  • Choose scab-resistant cucumber varieties, such as Marketmore 76.
  • Space vine crops adequately so that leaf surfaces will dry quickly.
  • Follow a two-year or longer rotation of cucumbers and other vine crops in your garden if space allows.

Last updated: 01/05/2023