WSU Extension

Hortsense

Caption: Coryneum blight symptoms on leaves and fruit
Photo by: R.S. Byther
  
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Ornamental Plum : Shothole (Coryneum blight)
(revision date: 5/19/2015)


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

Non-Chemical Management
  • Avoid overhead watering.
  • Prune and destroy dead buds and cankered twigs if present.
  • Rake and destroy infected leaves.
Select non-chemical management options as your first choice!

Chemical Management


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 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.

Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.
  • Bonide Fung-onil Multi-Purpose Fungicide Conc
    Active ingredient: chlorothalonil  |  EPA reg no: 60063-9-4
  • Hi-Yield Snake Eyes Dusting Wettable Sulfur
    Active ingredient: sulfur  |  EPA reg no: 7401-188-34911
  • Lilly Miller Sulfur Dust Fungicide/Insecticide Dust or Spray
    Active ingredient: sulfur  |  EPA reg no: 802-16
  • Safer Brand Garden Fungicide/Flowers, Fruit & Vegetables Conc
    Active ingredient: sulfur  |  EPA reg no: 42697-37
  • Soap-Shield Flowable Liquid Copper Fungicide [Organic]
    Active ingredient: copper octanoate  |  EPA reg no: 67702-2-56872
  • This list may not include all products registered for this use.
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Caption: Coryneum blight symptoms on leaves and fruit
Photo by: R.S. Byther