WSU Extension


Common Diseases
Armillaria root rot 
Botrytis blight (Gray mold) 
Crown gall 
Dead roots 
Downy mildew 
Dwarf mistletoe 
Leaf spots and blights 
Nectria cankers 
Phytophthora root rot 
Powdery mildew 
Pseudomonas bacterial canker 
Root rots 
Sclerotinia white mold 
Sudden oak death 
Tubercularia canker 
Verticillium wilt 

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Caption: Petunia stem rot
Photo by: R.S. Byther
Common Diseases : Sclerotinia white mold
(revision date: 4/30/2013)

Sclerotinia white mold is a fungal disease affecting many herbaceous flowers and vegetable crops. A stem rot and white fungal growth appear at the base of infected plants. Infected plants wilt and die. Hard, round, black resting structures (sclerotia) form in the white mold and often in the center of infected stems. The sclerotia of the fungus survive in the soil and infect subsequent plantings. White mold development is favored by overfertilization and moist conditions.
Management Options

Non-Chemical Management
  • Plow the field deeply once to bury sclerotia before planting.
  • Space plantings to provide good air circulation within and between rows.
  • Remove and destroy infected plants and plant debris. Do not compost infected plant material.
  • Rotate crops. Do not plant susceptible crops in previously infested soil.
  • Provide proper plant culture. Avoid overfertilization and overwatering.
Select non-chemical management options as your first choice!

Chemical Management

None recommended


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Caption: Petunia stem rot
Photo by: R.S. Byther
Caption: Sclerotinia white mold on sunflower
Photo by: R.S. Byther
Caption: Sclerotinia white mold on marigold
Photo by: L.J. du Toit
Caption: Interior stem showing white fungal growth and black sclerotia
Photo by: R.S. Byther