WSU Extension


Nectria canker 
Ash borer 

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Caption: Nectria canker fruiting bodies
Photo by: R.S. Byther
Ash : Nectria canker
(revision date: 4/28/2014)

Nectria canker is a fungal disease often found on twigs and branches that have been weakened by drought, frost damage, insect damage, or other diseases. Cankers are initially distinguished by discolored bark with coral or reddish fungal fruiting bodies. The cankers are sunken and often associated with wounds. Older cankers develop concentric, target-like rings of wood. Affected branches may have stunted or wilted leaves, or fail to produce leaves in the spring. Branches may be girdled.
Management Options

Non-Chemical Management
  • Avoid wounding trees. Do not prune in late summer or fall.
  • Do not leave stubs when pruning.
  • Plant trees or shrubs that are adapted to your climate. Minimizing frost damage and water stress increases disease resistance.
  • Provide proper plant care. Healthy plants are more resistant to disease.
  • Prune and destroy infected branches. Make cuts well below diseased tissues.
Select non-chemical management options as your first choice!

Chemical Management

None recommended


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Caption: Nectria canker fruiting bodies
Photo by: R.S. Byther