How to Manage Pests

Pests in Gardens and Landscapes

White mold
(Sclerotinia lettuce drop)—Sclerotinia spp.

White mold is a distinctive disease that most often affects stems and foliage at the base of plants. Affected tissue develops a soft, watery rot and white, cottony mycelium forms on the surface. Plants may wilt if stems are girdled by the decay. As affected tissue dries up, it turns yellow to white, and hard black sclerotia form on the surface or inside the dead stems.

Life cycle

Solutions

White mold is favored by a wet soil surface. Use of raised beds and careful furrow irrigation that does not overflow onto bed surfaces can help limit damage. Space plants well enough to allow good air circulation. Remove and destroy entire infected plants and crop residues as soon as you see the mold. Sclerotia can be destroyed by burying them 10 inches or more below the soil surface. Solarization may also give control.

Wilting of outer leaves on lettuce
Wilting of outer leaves on lettuce
Infected crown of lettuce
Infected crown of lettuce
White mold on brussels sprouts
White mold on brussels sprouts


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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