Tony Dickerson answers your questions
Q What has caused patches of bark to fall off my tree and the holes beneath? Colin Richardson, Alvechurch, West Midlands
A Your tree is infested with wood-boring insects, while the bark has been removed by a woodpecker in search of food. At some time in the past, the tree probably suffered some bark loss in the area of the infestation. Once a tree loses some of its outer bark, the inner wood is then liable to dry up and become vulnerable to fungal decay and various types of woodboring insect. Woodpeckers don’t bother healthy trees so it’s likely that the woodboring insects in the trunk of your tree have attracted their attention. The woodpeckers may have cleared out the affected parts of the trunk, but if there are still beetle grubs or other insects there, then they’re likely to return as long as the food resource remains available. It’s difficult to keep woodpeckers away from a tree because there are no effective repellent or scaring devices. Wrapping the trunk of the tree with some sort of material to act as a bandage may deter them, but that may not be a solution.
The heartwood of a tree is already dead tissue, so the activities of wood-boring insects or woodpeckers are not directly threatening to the tree’s health. The live tissue is immediately underneath the bark around the outer circumference of the trunk. Old trees sometimes have trunks that are entirely hollow and yet they still survive.
However, there’s an increased risk that the tree might be blown down in a gale. If it’s likely to fall on the house or cause other damage, it would be worthwhile consulting a tree surgeon who can advise on the safety aspects of retaining the tree.
There are no effective treatments for wood-boring insects or fungal decay in tree trunks, since any chemicals applied to the trunk are unlikely to penetrate far enough to control the insects and the fungal decay.
Sadly the only choices are removal of the affected part of the tree or, if this is impossible, either felling or allowing nature to take its course.