How to Manage Pests

Pests in Gardens and Landscapes

Shot hole disease (Coryneum blight)—Wilsonomyces carpophilus

Shot hole, or Coryneum blight, is a serious disease of almonds, apricots, nectarines, peaches, and other Prunus species in California. Reddish or purplish brown spots about 0.10 inch in diameter occur on new leaves and shoots. The spots expand and their centers turn brown. Tiny, dark specks sometimes form in the center of lesions, especially on leaves. Spots on young leaves have a narrow, light green or yellow margin and their centers often fall out as leaves expand, leaving "shot holes." Buds of peach, nectarine, and sometimes apricot are killed in the winter. Fruit may become rough and corky. Spotting occurs on the upper surface. Concentric lesions may develop on branches.

Life cycle

Solutions

Prune and dispose of infected tissue as soon as it appears. After leaf drop, inspect plants carefully and prune infected buds and twigs with lesions. Diligent sanitation and water management can provide adequate control where the incidence of shot hole is low. Avoid overhead sprinklers or use a low angle to avoid wetting foliage. Also, some varieties may be less susceptible. Where disease incidence is high, fungicides such as Bordeaux mixtures or fixed coppers may be applied. On peaches and nectarines, a dormant spray of copper in late fall will work well. On almonds, spray fungicides at petal fall in the spring.

Shot hole on young apricots
Shot hole on young apricots
Shot hole damage from left to right on peach, almond, apricot, and cherry
Shot hole damage from left to right on peach, almond, apricot, and cherry
Infected twig
Infected twig
Shot holes
Shot holes

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

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