Mountain Ash (Sorbus spp.)-Nectria Canker

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Cause Nectria cinnabarina (asexual: Tubercularia vulgaris) has been reported from Washington. A fungal disease often found on twigs and branches that have been weakened by drought, frost damage, insect damage, or other diseases.

Symptoms Cankers are distinguished initially by discolored bark with coral or reddish fungal fruiting bodies (perithecia). 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 may fail to produce leaves in spring. Branches may be girdled.

Cultural control

  • Avoid wounding trees. Do not prune in late summer or fall.
  • Do not leave stubs when pruning.
  • Plant trees or shrubs 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.