Botrytis Gray Mold of Vegetable Crops

Botrytis gray mold can affect numerous vegetable crops resulting in damage to plants and fruit. The disease occurs in field, high tunnel, and greenhouse production; however, conditions in protected agriculture environments (greenhouses and high tunnels) often lead to greater disease development. Cultural practices often provide adequate disease management, but fungicides are available for more severe infections. 

Botrytis Gray Mold Facts

  • Symptoms include development of tan-brown lesions, with a gray, fuzzy covering on leaves, stems, blossoms, or fruit (Figures 1 and 2).
  • Flowers and fruit are most commonly affected.  Dead, dying, and damaged tissue is most susceptible.
  • Once stems become infected, lesions frequently girdle stems resulting in wilting or plant death. Infected fruit quickly rot and become unmarketable both in the field and during post-harvest storage.
  • Wounding increases susceptibility to infection by Botrytis gray mold.
  • Disease development is favored by high humidity (>85%).
  • The pathogen overwinters in plant debris.
  • Disease is spread by movement of spores by wind, air, or water.
  • Botrytis gray mold is caused by the fungal pathogen Botrytis cinerea.
Figure 1: Botrytis gray mold stem lesions may expand to girdle stems. (Photo: Bruce Watt, University of Maine,

Figure 2: Fruit affected by Botrytis gray mold degrade quickly. (Photo: Paul Bachi, University of Kentucky Research and Education Center,


Cultural practices are often adequate for disease management; however, fungicides may be used preventatively or to protect plants during severe outbreaks.

  • Increase plant spacing.
  • Prune plants to improve air flow.
  • Monitor humidity  in greenhouses and high tunnels. Exchange air and/or run fans.
  • Remove and destroy heavily infected plants  and dead or damaged plant parts.
  • Avoid wounding plants.
  • Avoid overhead watering to reduce leaf wetness.

Commercial growers can find information on fungicides in the Vegetable Production Guide for Commercial Growers (ID-36) and the Southeast U.S. Vegetable Crop Handbook. Homeowners should consult Home Vegetable Gardening (ID-128) for fungicide information or contact a county extension agent for additional information and recommendations regarding fungicides.   

Additional Resources

  • Greenhouse Sanitation (PPFS-GH-4)
  • Home Vegetable Gardening (ID-128)
  • IPM Scouting Guide for Common Pests of Solanaceous Crops in Kentucky (ID-172)
  • Managing Greenhouse & High Tunnel Environments to Reduce Plant Diseases (PPFS-GH-1)
  • Vegetable Production Guide for Commercial Growers (ID-36)
  • IPM Scouting Guide for Common Problems of High Tunnel and Greenhouse Vegetable Crops in Kentucky (ID-235)

By: Kim Leonberger, Plant Pathology Extension Associate and Nicole Gauthier, Extension Plant Pathologist

Posted in Vegetables
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