Two-lined Chestnut Borer In Minnesota
Two-lined Chestnut Borer is a wood-boring insect that feeds underneath the bark of weakened oak trees. This causes dieback and branch death from the top of the tree down. Trees impacted by drought, compacted soil, disease, or defoliation are more susceptible.
According to the MN DNR (see article here), central Minnesota has recently seen large numbers of this pest in oak trees due to the stress of the droughts in 2021 and 2022. If you have oak trees in your landscape that you don’t want to lose, we recommend treating those trees with an insecticide to prevent attack. Contact us to set up an assessment with our ISA Certified Arborist.
How To Identify Infested Oak Trees
Oak trees infested with two-lined chestnut borer start to die from the top down in late summer. You may see reddish-brown leaves at the top of the tree that stay on the tree. Whereas, trees infected with oak wilt will lose their leaves. S-shaped galleries can be found underneath the bark of dying branches or trees.
Two-lined Chestnut Borer Treatment
ArborThrive’s ISA Certified Arborist recommends protecting high-value oak trees with systemic insecticide treatments to prevent attack. Treatments are applied either to the soil or directly into the trunk of the tree. Treatments are highly effective when used preventively and can also work on infested trees if it is 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 oak trees or other root disturbance.
Keep Your Trees Alive With ArborThrive!
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