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DescriptionBronze Birch Borer

Bronze birch borer (Agrilus anxius Gory) larvae are flattened, creamy-white, legless grubs with light brown heads. Adults are slender, olive-green to black beetles with metallic bronze reflections.

Plants Affected

The beetle attacks both native white birch and European weeping birch. While its typical host tree  would be mature birch trees 40 years or older, it will attack even young birch trees when population outbreaks occur.

Such an outbreak was triggered in Grande Prairie in the early 2000s by the onset of a drought cycle. The outbreak has not yet ended.

Symptoms

  • Dead limbs at the top of the tree.
  • D-shaped bore holes are visible below dead limbs. Bronze Birch Borer
  • Successive years of attack progress down the tree until it dies.

Controls

  • Ensure your birch trees are well watered during dry periods.
  • Leave low branches in place to keep the tree's shallow roots cool.
  • Don’t dig in the root zone.
  • As soon as damage is observed in the top limbs of the tree, prune out all deadwood at least 12 inches (30cm) below the lowest bore holes to ensure all beetles are removed.  Burn or chip the wood immediately.

Bronze Birch Borer     Bronze Birch Borer

Last updated: 12/11/2014 7:38:04 AM