WSU Extension

Hortsense

Boxwood
 
Disease
Box blight 
Canker 
Leaf spot 
Phytophthora root rot 
Insect
Boxwood leafminer 
Boxwood mite 
Boxwood psyllid 



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Caption: Boxwood Pseudonectria leaf spot
Photo by: R.S. Byther
  
Boxwood : Leaf spot
(revision date: 4/11/2018)


Biology
Boxwood leaf spot is caused by fungi which survive in fallen, diseased leaves beneath the plant. Leaves develop discolored spots and may turn tan or brown from the margins and tips inward. Small, black fruiting bodies of the fungus often appear on the discolored spots or the underside of the leaves. Leaf spot is favored by wet, humid weather and damp planting conditions.
Management Options


Non-Chemical Management
  • Prune and destroy infected and dead plant parts.
  • Collect and destroy dead leaves under plants and in branch crotches.
  • To reduce likelihood of infection, avoid overhead watering and space plants to provide good air circulation.
Select non-chemical management options as your first choice!

Chemical Management

Make fungicide applications in spring before new growth starts.

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

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Caption: Boxwood Pseudonectria leaf spot
Photo by: R.S. Byther