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FGCA > Conservation of Genetic Diversity > Species at Risk > Butternut > Butternut Canker > Symptoms

Butternut Canker Signs and Symptoms

Some of the common signs and symptoms of the butternut canker include:

  • dying branches in the upper, sunlit crown (shaded branches die off normally)
  • sunken, elongated, diamond-shaped cankers, dark brown to black in colour, found on the branches or the stem
  • older cankers may show successive rings of callus loosely covered with shredded bark
  • in spring, a thin black fluid oozes from cracks in the bark
  • in summer, fall and winter, the black fluid leaves a dried sooty stain on the outside of the bark at the canker site
  • underneath the bark, the wood is stained dark brown to black in a diamond shape
  • epicormic branching below dead or infected areas on stem or branches

Canker on trunk

Epicormic branching

Crown dieback due to canker infection

Recent canker on trunk

Mature butternut canker