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Extension > Garden > Diagnose a problem > What's wrong with my plant? > Deciduous Trees > Black Walnut > Large woody growth on trunk

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Black Walnut > Trunk/Branches > Large woody growth on trunk

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  • Image: Burls 1
  • Image: Burls 2
  • Image: Burls 3


  • Large round to semi-circular swellings along main trunk or large branches
  • Many buds of sprouts may be present on the exterior of the burl
  • Common on sugar and Norway maples
  • Burls continue to grow as the tree grows
  • While burls do not kill trees directly they can reduce a tree's health and lifespan
  • There is no known cause for burls
  • More information on Burls

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