Plum, Prune (Fresh): Shothole (Coryneum blight)

categories: Plum, Prune (fresh) Plum, Prune (Fresh) Diseases Tree Fruits

revision date: 2022-12-05 12:00

Coryneum blight symptoms on leaves and fruit.
Coryneum blight symptoms on leaves and fruit
Photo by: R.S. Byther

Biology

Coryneum blight is a fungal disease. Lesions on leaves are initially small, purplish, round to oval areas which expand into brown spots with light centers. The lesions are typically up to 1⁄4″ in diameter. The infected spots on leaves often die and drop out in warm weather, giving leaves the characteristic “shothole” appearance of the disease. The fungus probably overwinters on the bark and in infected buds. Spores are easily spread by water.

Management Options

Use Integrated Pest Management (IPM) for successful plant problem management.

Non-chemical Management

Select non-chemical management options as your first choice!

  • Prune and destroy dead buds and cankered twigs if present.
  • Rake and destroy infected leaves.
  • Avoid overhead watering.

Chemical Management

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

  • If fungicides are used as part of your management program, apply at 50% leaf fall in late autumn before heavy rains to protect leaf scars (except sulfur products).
  • Chlorothalonil, IMMUNOX, or sulfur products can also be applied in spring when petals fall.
  • NOTE: Bonide Fung-onil is for spring use only.
  • 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.

Approved Pesticides

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