Bronze Birch Borer
All species of birch in Bucks and Montgomery County may be attacked by the bronze birch borer, but some species are more susceptible than others. Look for small branches towards the top of the tree beginning to thin and die back. Leaves on the infested branches may be stunted and yellow. Birches which are attacked by this pest may die within 3-4 years. These pests create meandering galleries which cut off the uptake of water and nutrients to the uppermost parts of the tree. This flat-headed borer will leave D-shaped exit holes. The adult borers are approximately 3/8" long, metallic-coppery colored beetles. The larvae are segmented, legless grubs approximately 1/2" long. They feed laterally around the branch on phloem tissue, etching the xylem.
The best protection from the bronze birch borer is prevention. Because this pest attacks weakened and stressed trees, care and attention should be given to maintaining tree health by watering during drought, mulching, and minimizing damage to the root zone that could cause root injury and stress. For new plantings, consider hardy species that are more stress tolerant. Infested branches and deadwood should be removed if choosing to save the host tree. High value trees at risk for infestation by the bronze birch borer may be treated preventatively with a soil or trunk injected insecticide. This can also protect the tree from the birch leaf miner, which causes additional stress by feeding on the leaves. The size of the tree, time of year and also proximity to water must be considered when choosing an appropriate treatment.
Contact Plant Health Solutions for proper diagnosis and to develop a treatment plan.