Splitting bark on ash tree

Asked August 9, 2015, 11:54 PM EDT

I have noticed that our 20 year old Ash tree has a 6-8" split on many of the branches (see photo). From the street and yard, our Ash tree looks healthy and appears fully green. We have not pruned the tree heavily, only limbed up the tree through the years. We have used preventative measures for the Emerald Ash Bore, and have been checking the trunk periodically for D shaped holes on the trunk. None have been seen. Though several trees in the neighborhood have been infested and died, our tree does not resemble the characteristic death from the top down as by all appearances, looks healthy. However, a few small, younger branches that are not seen except when looking up into the tree from the ground are bare as if the tree is "self-pruning" itself. One older branch does not look healthy as it does not have leaves (see photo). On one branch it appears that near it's split bark, water shoots are growing indicating stress (see photo). I have read about sunscald and sunburn, but not sure how to identify that. What do you think is the cause? Your help is appreciated.

Jefferson County Kentucky trees and shrubs tree health ash trees

1 Response

A wound like this was likely caused by sun scald. Sun scald is the freezing and thawing that occurs in winter from direct or reflected light. Established, healthy trees can overcome such wounds and continue to grow. Pruning would help the tree recover from the excessive 'water sprouts' due to limb death/breakage.

The tree should internally compartmentalize around the wound if it can. Sealers or sprays will not help and may actually cause more damage.

A certified arborist can help you determine if the branch that is failing needs to be removed or there are other unseen issues that the tree may have.

The following link is to a publication on tree wounds by plant pathologist, Dr. Hartman and Brian Eshenaur (arborist) at the University of Kentucky.

I think you will find it helpful:


Feel free to contact our office if you have other questions.

Let me know if I can help you further!

Carol Wilder
Horticulture Technician
Jefferson County Cooperative Extension Service
810 Barret Ave
Louisville KY 40204