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Birch dieback

Infects

Birch trees, most often European White Birch and its varieties, including Cutleaf Weeping Birch. Paper birch is less susceptible.

Symptoms

  • First stage Tree becomes stressed due to high temperature, low soil moisture or bark injury.
  • Second stage The Bronze Birch Borer will attack the tree. A few leaves begin to wilt at the top of the tree, followed by a few twigs and then small branches. Finally a large branch or 2 will die. You can see the adult Bronze Birch Borers emerging from the tree in June from D-shaped holes.

Cure

The tree can only be saved if about 1/3 of the crown has been infected. If the infection has spread past this point, the entire tree should be cut down and the wood taken to the landfill.

IPM Toolkit

Preventative tools

  • Avoid stressing the tree:
    • Ensure it receives 2.5 cm of water per week.
    • Apply mulch to the base of the tree to hold in soil moisture.
    • Fertilize the tree every other spring with 20-8-8 fertilizer.

Physical tools

  • Prune any dead or dying wood several feet below any visibly dead wood in August. Dispose of the wood at the landfill.

Biological tools

  • Woodpeckers and some sapsuckers will eat the bronze birch borer.

Chemical tools

  • Not applicable.