Tree Killers: Butternut Canker

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  • Common English name: Butternut Canker
  • Other names:
  • Latin (scientific) name: Sirococcus clavigignenti-juglandacearum

Threat type

150x150 diseases

History in Canada

  • the Butternut tree occurs in southern Ontario, southern Quebec, and New Brunswick
  • the canker was first documented in the US in 1967 but it may have arrived there before 1940
  • the disease reached Canada in 1990
  • the disease has been documented across the entire range of Butternut in Canada


  • a fungus disease that infects and kills Butternut trees (Juglans cinerea)
  • the disease enters a wound and kills inner bark on branches generally in the lower canopy
  • gradually, the fungus kills the upper canopy and spreads down the tree to attack trunk tissue
  • when the fungus has girdled the trunk, the tree dies
  • the disease is probably from outside North America
  • the fungus kills mature trees as well as saplings and seedlings
  • on branches, the cankers appear as white patches with a black centre
  • on the trunk, the fungus causes deep grooves and gashes in the bark that often ooze a black jelly-like material containing the spores of the fungus
  • the spores may be spread by rain and insects

Impact on Trees

  • the Butternut tree is an important forest species that provides valuable wood for furniture and nut crops that are used by wildlife and were important to early settlers
  • no tree strains are known to have resistance to the disease
  • in the southern US, over 75% of Butternut trees have been killed by the canker
  • when the trunk is killed, Butternut will not resprout from the base
  • Butternut is now considered Endangered in Canada due to the impact and potential impact of the disease

What can be done to control this tree killer?

  • there is no known cure for trees infected with the canker
  • studies are underway across the range of Butternut to locate disease-resistant trees

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