Extension > Garden > Diagnose a problem > What's wrong with my plant? > Deciduous Trees > Willow > Unusual growth or swelling on trunk or branches
Willow > Trunk/Branches > Unusual growth or swelling on trunk or branches
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Willow pine cone midge gall
Rhabdophaga strobiloides
- Light green, pine cone-shaped growth on end of twigs where bud is normally found
- Gall grows to about one inch long
- Old galls turn light brown and remain on the tree during winter
- More information on Willow pine cone midge gall
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Crown 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
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
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
