Bronze Birch Borer In Minnesota
Bronze birch borer is an insect that feeds underneath the bark of weakened birch trees. This causes dieback starting at the top of the tree and works downward. Trees impacted by drought, compacted soil, disease, or defoliation are more susceptible to bronze birch borer.
How To Identify Infested Birch Trees
Birch trees infested with bronze birch borer start to die from the top down in late summer. It may start with sparse foliage on the upper branches, eventually turning to dead branches. On the trunk and branches of the tree, you may see small D-shaped holes and/or bulges in the bark. Those bulges are where the bronze birch borer larvae are feeding underneath the bark of the tree.
Bronze Birch Borer Treatment In Minnesota
ArborThrive recommends protecting high-value birch trees with insecticide treatments to prevent bronze borer attack. Treatments are highly effective when used proactively and can also work on infested trees if caught early enough.
Other prevention measures:
- Water trees with one inch of water per week during droughts.
- Provide a 3-4 inch layer of wood mulch around the base of the tree to preserve soil moisture.
- Avoid any soil grade changes near birch trees or other root disturbance.