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United States
Department of Agriculture

Forest Service

Northeastern Area
Region 8


Butternut Canker

  Crown dieback due to infection by the fungus.
  Crown dieback due to infection by the fungus.

Butternut canker is caused by a fungus known as Sirococcus clavigignenti-juglandacearum which is killing butternut (Juglans cinerea) throughout its range in North America.  Butternut is closely related to black walnut (Juglans nigra), which is not naturally susceptible to the disease.

To determine if your butternut has butternut canker, look for:

  • dead branches or a dying top.
  • discolored bark which, in spring, has an inky black fluid oozing from cracks in the cankered bark and in summer has sooty patches usually with a whitish margin.
  • young cankers which may appear elongated and sunken into the bark.  Often these occur around leaf scars, buds or wounds.
  • old cankers which may have loose bark covering them and several layers of overgrown trunk tissue.
  • stained wood beneath the bark which appears dark brown to black in an oval shape.


Black sooty appearance of cankers on the trunk during the summer.   Stained wood beneath the bark.   Older cankers on the trunk.

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