White mold—Sclerotinia sclerotiorum
White mold generally appears on tomato plants at flowering. Symptoms include water-soaked areas on flowers
and at stem joints where senescent flower petals have fallen. The infection quickly kills stems, which
eventually dry and take on a bleached appearance. Water-soaked stem lesions may also appear at the soil
line if senescent plant debris is present around the plant. Affected areas generally show white, cottony
mycelium that soon produces large, irregularly shaped black sclerotia. Infected fruits turn gray and rot.
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. Avoid overhead sprinklers. 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.
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Bleached
appearance of tomato stems
Black
sclerotia on bleached stems
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