FLAT HEADED APPLE TREE BORER
The flat headed apple tree borer is one of the serious pests of apple tree. It has many hosts and causes major problems in commercial nurseries. These borers generally attack plants which are under stress or weakened. They are very dangerous as a single larva can kill a young tree. The larval stage of the flat headed borers is the most damaging to trees as they feed in the cambium layer just under the bark of the trunk and scaffold branches. The damage is done by creating galleries under the bark which may kill the tree. This results in restricting the movement of water and other nutrients to branches which causes die-back of lateral twigs; if infestation is high it can kill the tree.
Damage occurs when the larva of the flat headed borer feeds on the bark that damages the cambium layer and restricts the flow of nutrients through out the tree. The borers generally attack young trees and single larva is capable of killing a tree. If tunnels packed with dust are founded under bark, it means there is larval activity. The galleries, which nearly always begin on the sunny side of the tree, may extend completely around the tree thus girdling and killing the tree or infested branches. A full-grown larva may bore from 1 to 2 inches deep in the wood of the tree. Bark exterior to the galleries or mines may die and peel off.
The best way is to look throughout the summer for the adults on exposed sunny patches of the bark. Also look for the signs if there is any die-back of the twigs or branches. Find any sap flowing out from cracks in the bark and try to find the larval galleries at these points.
The Flat headed apple tree borer starts their life cycle when the females lay their eggs in the crevices of the barks of the apple tree generally in late spring. The female beetles choose deeper cracks than others because this offers their eggs extra protection through which their larvae can feed. The larvae damages the apple trees by boring through the bark from the outer layer to inner layer, hence making a tunnel in the tree. These tunnels damage the tissue and restrict the water and nutrients movement to the tree. In the following spring, mature larvae bore into the heartwood to pupate. Adults feed at the base of the twigs, on partially defoliated trees. There is one generation per year.
The best to get rid from these borers is to keep the trees in vigorous growing condition by doing adequate watering and fertilization. Weakened apple trees and those newly planted are most susceptible to borer damage. Any branches which show sign of damage should be pruned out and destroyed. Vegetation should be removed from the base of the tree and the base should be mulched in order to keep them vigorous.
There are several pesticides to treat for Flat headed apple tree borer by drench treatments from February to March. Spray the bark of the trunk and limbs three times in May, June and July. The pesticides include Imidachloprid, Bifenthrin and Chlorpyrifos.