This highly destructive insect aggressively attacks all ash trees. Untreated ash trees die in 3-4 years. These flat headed borers originated from Asia and were first detected in Michigan in 2002. This insect has since spread across America and was first detected in Boulder, CO in 2013. Emerald Ash Borer is on the move and was recently detected in Broomfield, CO in August of 2019 and Westminster, CO in September of 2019. The flight period for adults occurs in May where they seek out new ash trees for food and reproduction.
Flow of nutrients throughout the vascular system of the tree is interrupted, therefor growth decreases and die back occurs.
New growth will occur at the base of the tree since the flow of nutrients can no longer reach the canopy.
Here you can see an almost perfect "D" where the borer has exited the tree.
These galleries disrupt the vascular system of the tree.
A trail of "dust" at the base of the tree is left where boring occurred.
Woodpeckers seek the larvae hidden within the tree's tissue.
Preventive treatments include soil based, trunk sprays and trunk injections. Treatments depend on the health of the plant and other factors to be considered are:
Soil based and trunk sprays are annual treatments done March-September to kill the larvae.
Trunk injections will last up to 2 years and are usually done in the fall.