How to Manage Pests

Pests in Gardens and Landscapes

White rot—Sclerotium cepivorum

Leaves of infected plants show yellowing, leaf dieback, and wilting. Leaf decay begins at the base, with older leaves being the first to collapse. A semiwatery decay of the bulb scales results. Roots also rot. A fluffy white growth develops around the base of the bulb. As the disease progresses, this mycelium becomes more compacted, less conspicuous, with numerous small spherical black bodies forming.

Life cycle

Solutions

The most effective controls for white rot are avoidance and sanitation. Use of raised beds and careful furrow irrigation can help limit damage. Space plants well enough to allow for good air circulation. Destroy diseased plants. To prevent spread in soil, do not compost. Do not replant onions or garlic in that area; fungus survives in soil for years. Solarization will help control this disease.

Yellowing and wilting of infected onions
Yellowing and wilting of infected onions

Statewide IPM Program, Agriculture and Natural Resources, University of California
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Agriculture and Natural Resources, University of California

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