How to Manage Pests

Pests in Gardens and Landscapes


Molds may start to invade the nuts in midsummer if the husks have been damaged by sunburn, drought, or husk fly; damaged husks adhere to the shell and allow the mold to penetrate into the kernel, usually through the soft suture. The chance for mold infestation increases rapidly once the husks start to split. Mold develops rapidly under warm, moist conditions. Whitish gray mycelia form on the surface of the kernel and often bluish green to grayish black spores, depending on the mold species.


To prevent contamination by molds as much as possible, protect the husk from damage and harvest and dry the nuts rapidly.

Mold penetrating walnut
Mold penetrating walnut

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