Sclerotinia diseases can infect numerous vegetable crops and can be known by many different names. The most commonly affected vegetable hosts include beans (white mold), cabbage (head rot), lettuce (drop), and tomato (timber rot). Vegetable crops in commercial production (field and high tunnel) and home gardens may become infected. Severe infections may result in plant death, leading to significant losses for growers.
Sclerotinia Disease Facts
- Most infections can be identified by a white, cottony fungal growth at or near the soil surface (Figure 1). As disease progresses, small, black, irregularly shaped overwintering structures (sclerotia) develop (Figure 2). Information on crop specific symptoms is detailed in the publication Sclerotinia Diseases of Vegetable Crops (PPFS-VG-29).
- Stems, crowns, lower leaves, and fruit may become infected.
- Initial infection occurs during spring following wet weather and cool temperatures (55° and 75°F).
- Sclerotia may survive for up to 5 years in soil.
- Disease may be spread through movement of infested soil, tools, or infected plants.
- Caused by the fungi Sclerotinia sclerotiorum.
Management Options
Once Sclerotinia is confirmed in a field, management is critical to reduce future crop loss.
- Rotate to non-host crops, particularly in spring; Sclerotinia diseases are mostly limited to April and May in Kentucky.
- Select resistant or tolerant vegetable cultivars.
- Utilize disease-free, certified seed.
- Inspect transplants prior to planting.
- Increase airflow by properly spacing plants and prune as needed. Maintain ventilation in greenhouses and high tunnels.
- Apply a mulch layer to prevent splash.
- Avoid wounding plants.
- Avoid overhead watering and excessive soil moisture.
- Promptly remove infected plants.
- Remove and destroy crop residues.
- Deep till to bury sclerotia (8 to 10 inches).
- Avoid movement of infested soil. Work in clean fields first and infested sites last to prevent spread.
- Wash and disinfect tools, equipment, shoes, and clothing after working in infested fields or tunnels.
- Soil solarization may be effective in destroying sclerotia if soil temperatures can be raised above 104°F. Research is ongoing to determine solarization recommendations for Kentucky climates.
- Infected fruit may not show symptoms at harvest, but disease may develop in storage. Damaged, wounded, and diseased materials should be discarded.
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. Fungicides labeled for management of Sclerotinia diseases are not labeled for homeowner use.
Additional Resources
- Sclerotinia Diseases of Vegetable Crops (PPFS-VG-29)
- Home Vegetable Gardening (ID-128)
- Southeast U.S. Vegetable Crop Handbook (SEVEW)
- Vegetable Production Guide for Commercial Growers (ID-36)
- Scouting Guides for Problems of Vegetables (mobile website)
- Cleaning & Disinfecting Home Garden Tools & Equipment (PPFS-GEN-17)
- Cleaning & Sanitizing Commercial Greenhouse Surfaces (PPFS-GH-07)
By Kimberly Leonberger, Plant Pathology Extension Associate, and Nicole Gauthier, Extension Plant Pathologist
Kentucky Pest News 