Sclerotinia (White Mold)

What is it?

Sclerotinia survives in soil as hard black resting bodies (sclerotia) that germinate to infect senescing flowers and tissue contacting the soil. From those infection courts it spreads into stems, pods and crowns, especially under cool, humid, dense-canopy conditions.

How to identify it

• Water-soaked lesions on stems, pods, crowns or leaves that rot rapidly.
• Fluffy white cottony mould on infected tissue in humid conditions.
• Hard black sclerotia (like rat droppings) inside stems or on the surface.
• Sudden wilting and collapse of individual plants or patches.

Life cycle & spread

Sclerotia survive years in soil; under cool, moist conditions they germinate to release spores that infect flowers/senescing tissue, then the fungus colonises stems and pods and forms new sclerotia. Bloom is the critical infection window.

Conditions that favour it

Cool, wet, humid weather; dense canopies that stay wet; flowering stage; and fields with a history of white mold (sclerotia in soil).

Damage and how it spreads

Rots stems, pods and crowns, killing plants and destroying yield; sclerotia persist to infest future crops. Severe in dense, high-yield canopies.

Monitoring & scouting

Watch the bloom window in cool, wet seasons; assess canopy density and field history; act preventively at early bloom rather than after collapse.

How to control it

1. Protect the bloom infection window preventively;
2. open canopies and improve airflow;
3. manage irrigation to reduce canopy wetness;
4. rotate away from susceptible hosts;
5. bury or avoid spreading sclerotia.

Preventing it next season

Rotation away from susceptible hosts, canopy/airflow management, irrigation timing to reduce wetness, sanitation, and preventive sprays in the bloom window.

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