How to Manage Pests

Pests in Gardens and Landscapes

Pest identification and confirmation—Rhizopus rot

Rhizopus rot is often confused with gray mold. However, fruit infected with Rhizopus leaks its contents, whereas fruit infected with gray mold does not leak.

The fungal growth formed on Rhizopus-infected fruit can be distinguished from gray mold by examining it with a hand lens. Tiny but conspicuous, spherical spore-forming structures called sporangia are present, each one on the end of a hairlike stalk about 0.10 inch long. Sporangia are white when first formed and turn black as they mature. Botrytis does not form sporangia, although masses of spores resembling tiny clusters of grapes may sometimes be seen. Both Botrytis and Rhizopus can be present on the same fruit.

Sporangia of Rhizopus rot
Sporangia of Rhizopus rot
Spores of Botrytis rot
Spores of Botrytis rot

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