Plant Problem Diagnosis Key / Diseases
Disease
White mold (Sclerotinia)
Sclerotinia sclerotiorum
A fungus with over 400 hosts, including beans and sunflower, that rots stems and heads in cool, wet, dense canopies. Its black resting bodies survive in soil for years.
Signs
- Fluffy white growth on stems, pods or heads.
- Hard black bodies on or inside the stem.
- Tan to off-white, dry, brittle stems; all leaves on that stem wilt.
What favors it
Cool (51-68 °F) weather, moist soil and dense plantings.
Prevention
- Space plants so air moves through and dries them.
- Use drip or soaker hose instead of sprinklers.
- Do not compost infected plants; the black bodies can survive it.
Often confused with
Sources
- White mold in the gardenUniversity of Minnesota Extension
- White Mold Disease on FlowersUniversity of Maryland Extension
Treatment by crop
Cultural, biological and chemical options in the order to use them, and notes written for each crop.
Identification is free. Treatment is on the Home and Pro plans.
Questions in the key that lead here
- Look the plant over, leaf undersides included. Are insects, mites, slugs, eggs, webbing or droppings on it?
No, only damage or discoloration - Where is the problem?
The whole plant or whole stems - How is the soil or media?
Moist or wet - Lift the plant or pull back the media at the stem. What do the roots look like?
White or cream, firm - Which plant is wilting?
Another plant - Slice the lower stem lengthwise. Is the tissue just under the skin streaked brown?
No, it looks clean - What else is going on?
Fluffy white growth on the stem with hard black bodies
Not a match? Start the key or describe what you see.
More photos
More from university Extension: search Extension pages on white mold, or find a plant diagnostic lab through your state's Extension.
Other diseases
- Anthracnose
- Apple scab
- Bacterial leaf scorch
- Bacterial leaf spot
- Bacterial wetwood (slime flux)
- Bacterial wilt of cucurbits
- Black knot
- Black spot of rose
- Bleeding canker
- Boxwood blight
- Canker diseases
- Cedar-apple and related rusts
- Crown gall
- Damping-off
- Downy mildew
- Dutch elm disease
- Early blight and Alternaria leaf spot
- Elm yellows (phloem necrosis)
- Fire blight
- Fusarium wilt
- Gray mold (Botrytis)
- Late blight
- Mosaic viruses
- Needle cast and tip blight
- Oak wilt
- Powdery mildew
- Root and butt rot
- Root rot (Pythium and Phytophthora)
- Rust
- Septoria leaf spot
- Shade tree anthracnose
- Sooty mold
- Tar spot of maple
- Tomato spotted wilt and impatiens necrotic spot viruses
- Verticillium wilt
- White pine blister rust