Plum pockets is caused by a fungal infection of the leaves, twigs, and small branches. The fungus overwinters on twigs or bud scales. Infection occurs on young plant parts in the spring. The affected plant parts are distorted and swollen, with leaves often developing a yellowish to reddish color and blister-like distortions. Fruits (if produced) are also affected, becoming swollen, spongy, and yellow to dark brown or black in color, then turning dry and hardened (mummified). Mummified fruits serve as another source of infection.

Management Options

Non-Chemical Management

Prune and destroy all infected tissues.
Clean up and destroy all fallen fruit from beneath trees. Also remove fruit or leaves that remain on the tree into the winter.

Select non-chemical management options as your first choice!

Chemical Management

IMPORTANT: Visit Home and Garden Fact Sheets for more information on using pesticides

Apply during the winter dormant season. Homeowners should not make foliar applications to trees over 10 ft tall. Consult a commercial pesticide applicator for treatment of trees and shrubs over 10 ft. tall.

Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.

Bonide Liquid Copper Fungicide Conc/Organic Gardening
Active ingredient: copper octanoate | EPA reg no: 67702-2-4
This list may not include all products registered for this use.

Images

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Caption: Plum pocket infected fruit Photo by: R.S. Byther

WSU Extension

Hortsense