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Willow > Trunk/Branches > Unusual growth or swelling on trunk or branches

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  • Willow pine cone midge gall 1

    Credit: Mary Ellen (Mel) Harte, Bugwood.org

  • Willow pine cone midge gall 2

    Credit: D. Profant, Hocking College

  • Willow pine cone midge gall 3

    Credit: J. Hahn, University of Minnesota

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green arrowWillow pine cone midge gall
Rhabdophaga strobiloides

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  • Crown gall 1

    Credit: Florida Division of Plant Industry Archive, Florida Dept. of Agriculture and Consumer Services, Bugwood.org

  • Crown gall 2

    Credit: Florida Division of Plant Industry Archive, Florida Dept. of Agriculture and Consumer Services, Bugwood.org

  • Crown gall 3

    Credit: M. Grabowski, University of Minnesota

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green arrowCrown gall
Agrobacterium tumefaciens

  • Round to irregular woody overgrowth or tumor at soil line or on roots
  • Small round woody galls can occur on branches
  • Young galls are soft, light green or white
  • Old galls are hard, dark colored or black
  • Occasionally galls are seen higher on the stem
  • More information on Crown gall...
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  • Willow witches’ broom 1

    Credit: M. Grabowski, University of Minnesota

  • Willow witches’ broom 2

    Credit: M. Grabowski, University of Minnesota

  • Willow witches’ broom 3

    Credit: M. Grabowski, University of Minnesota

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green arrowWillow witches' broom
Aster yellows group phytoplasma

  • Witches' brooms, a cluster of numerous small weak shoots arising from one point on a branch, occur randomly throughout the tree
  • Leaves on branches within witches' broom are stunted
  • Twigs within witches' broom often die over winter
  • More information on Willow witches' broom...
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  • Poplar gall borer 1

    Credit: Mike Ostry, USDA Forest Service, Bugwood.org

  • Poplar gall borer 2

    Credit: USDA Forest Service, North Central Research Station Archive, Bugwood.org

  • Poplar gall borer 3

    Credit: MN Dept. of Natural Resources Archive, Bugwood.org

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green arrowPoplar gall borer
Saperda inornata

  • Twig becomes swollen where larvae are feeding under bark
  • Branch tips die and/or break above the gall
  • Also found on aspen and poplars
  • Fully grown larvae are up to 1" long, cylindrical body, creamy-white and legless
  • More information on Poplar gall borer...

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