Disease

White mold

Fluffy white mold and hard black seed-like bodies on rotting stems of beans, lettuce and many flowers in cool, wet weather.

What you'll see

• A soft, wet rot on stems near the soil or on pods and leaves, and plants that wilt and collapse.
• Fluffy white mold over the rotten parts in damp weather.
• Hard black bodies 1/4 to 1/2 inch (0.5 to 1 cm) across in the white growth or inside hollow stems.

Why it happens

A soil fungus survives for years as hard black bodies. In cool, moist weather they release spores that infect fading flowers and wet stems, especially in dense plantings.

How to fix it

1. Remove and bin infected plants promptly, before the black bodies drop into the soil.
2. Don't compost them; home heaps don't get hot enough to kill the fungus.
3. Space plants and water at the base so leaves and the soil surface dry quickly.

Keep it from coming back

• Keep beans, lettuce, cabbage-family crops and squash out of infected beds for at least 2 years.
• Use raised beds, and avoid wetting the soil surface more than needed.
• Clear away fading flowers and plant debris where spores land.

Sources

• UC IPM: White mold (vegetables)
• RHS: Sclerotinia disease
• University of Maryland Extension: White mold disease on flowers

General guidance, not a diagnosis. For valuable, edible or outdoor crops, check with a local extension service or plant expert. Use any product exactly as its label says, and keep children and pets away while it dries.