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Question from Miles, Draper, UT (received 8/10/20) -

I have one white ash and 4 green ash trees in my yard. The green ash trees appear to have some bore holes in the bark on the trunk and the canopy is droopy and dying in places. Is there something I can do to help them out? What is going on?

Answer from Dr. Mike Kuhns, USU Extension Forester and Professor (sent 8/11/20) -

Miles,

Your green ashes have ash borer (also called lilac borer). It is a VERY common pest on ashes, and especially green ashes. The only treatment for them is to spray insecticide on their trunk and larger branches in the spring every year or two to kill the insects that are on the trunk and to block their entry. You can’t kill them once they are inside the tree. Unfortunately, the spray doesn’t block the entry of new ones very well either. This is the reason I rarely recommend planting of green ashes in Utah.