Sclerotinia White Mold
Sclerotinia sclerotiorum
0 host plants · Fungal
Last updated
What Should I Do?
- Rotate with non-host crops (grains, grasses) for 3+ years to reduce sclerotia in soil.
- Space plants to promote air circulation and rapid drying of foliage and soil surface.
- Avoid overhead irrigation; use drip irrigation to keep foliage dry. Time irrigation so plants dry before evening.
Quick Reference
Management
Spring through early summer (April-June in the Puget Sound region). Flowering and early fruit set are peak vulnerability periods because the fungus preferentially colonizes senescing flower petals as an entry point. source: PNW Plant Disease Management Handbook
Cool to moderate temperatures (59-70°F optimal, range 50-75°F). Relative humidity above 85%. Requires sustained moisture at the soil surface for apothecial development. Dense canopy and poor air circulation increase infection risk. Most active during cool, wet spring weather. source: PNW Plant Disease Management Handbook
Cultural Controls
- Rotate with non-host crops (grains, grasses) for 3+ years to reduce sclerotia in soil. PNW Plant Disease Management Handbook
- Space plants to promote air circulation and rapid drying of foliage and soil surface. PNW Plant Disease Management Handbook
- Avoid overhead irrigation; use drip irrigation to keep foliage dry. Time irrigation so plants dry before evening. PNW Plant Disease Management Handbook
- Avoid excessive nitrogen fertilization, which promotes dense canopy and prolongs moisture. PNW Plant Disease Management Handbook
- Remove and destroy infected plants promptly; do not compost infected material (sclerotia survive composting). PNW Plant Disease Management Handbook
- Plant in well-drained soils. Improve drainage where possible. PNW Plant Disease Management Handbook
Cool, moist conditions in the Puget Sound region favor Sclerotinia development, particularly in spring through early summer. Dense plantings with poor air circulation are most at risk. Not a serious concern on squash or cucumber in this region.