How to Manage Pests

Pests in Gardens and Landscapes

Seasonal development and life cycle—Botrytis rot

The fungus that causes gray mold and blossom blight, Botrytis cinerea, is widespread, infecting dead or dying plant parts and causing decay on many crops. In the absence of hosts, the fungus can survive as small black resting structures called sclerotia or in infected plant debris.

When it is humid and cool, spores are produced on moldy fruit, other hosts, plant debris, or sclerotia. They are spread by wind and splashing water. During flowering, germinating spores may infect flowers, causing blossom blight or invading developing fruit. Young fruit may decay soon after infection or the fungus may remain dormant until later. Spores produced continue to infect other fruit throughout the season. The incidence of fruit infection increases with the length of time fruit remains wet.

Gray mold is favored by cool, damp conditions, especially rainy weather. Botrytis is most active at temperatures of about 65° to 75° F.

Blossom infection
Blossom infection
Early infection
Early infection
Fungus over fruit
Fungus over fruit
Velvety gray spores
Velvety gray spores

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