Diagnosis not good for damaged trees

Posted on Apr 27 2016 in Backyard

EdLaughlinOur beautiful yellow “butterfly” magnolia tree is losing bark at the base area of tree. I was desperate and sprayed it, but the damage appears to be spreading up the tree. Can you please tell us what is damaging this tree?

— Edward Laughlin, Holland, Ind.

It is difficult to determine the initial cause of the injury to the lower trunk, but there are several common culprits. The thin bark on young trees can be susceptible to what is termed “frost cracking” – a splitting of the bark as a result of rapid temperature changes during cold, but sunny winter days. The thin outer bark expands in the heat of the sun, but rapidly contracts as the temperature drops at sundown. The bark contracts faster than the inner wood resulting in split bark. This splitting of the bark is also known as “southwest injury” since it is most likely to occur on the southwest facing side of the trunk.

Another possibility is mechanical injury caused by “mower or weed whip blight” when these machines get too close to the trunk and knock off pieces of bark. Rodents and rabbits can cause similar injury when they feed on tender young bark.

Spraying the trunk will not help, and most tree experts feel that the tar-based sprays and other wound dressings actually interfere with the natural wound closure process in trees. Unfortunately, there just isn’t much you can do after trunk injury occurs. Trees can survive for many years with such injury, but it is always a potential for disease, insect pests and decay to cause further injury.

Purdue Forestry has an excellent publication discussing mechanical injury to trees and how to prevent such injury: https://www.extension.purdue.edu/extmedia/fnr/fnr-492-w.pdf.species until and unless you can get this problem diagnosed.

Purdue Publication ID-477, Stress-related Conifer Dieback, provides more information on the possible causes. You might consider taking additional photos and perhaps an actual sample of a branch that still has some green in addition to the brown needles to your local county office of Purdue Extension. Or you can submit directly to the Purdue Plant and Pest Diagnostic Lab.

I lost a beautiful large tree last year. It’s the second one in the past seven years. Would you be able to see from the photo what might be happening? I have more beautiful trees on my property that I would like to save if I can.

— Laura Payne, Elizabeth Ind.

While I can’t be certain from the photo you submitted, from the pattern of the remaining bark I wonder if this might be an ash tree. If so, a prime suspect would be the emerald ash borer, a serious and fatal pest of ash trees throughout most of Indiana, including your county. If you have additional ash trees, you’ll need to assess their health and decide whether the remaining trees are healthy and valuable enough to invest in protecting them.

Purdue Entomology has an excellent website that will help you identify both the ash trees as well as the emerald ash borer and walk you through the decision making steps for managing the problem: https://extension.entm.purdue.edu/EAB/index.php?page=management/homeowners.

You might also contact your Harrison County office of Purdue Extension for additional information and assistance in identifying the problem: https://extension.purdue.edu/Harrison/pages/aboutus.aspx.


B. Rosie Lerner is the Purdue Extension consumer horticulturist and a consumer of Tipmont REMC. Questions about gardening issues may be sent to: “Ask Rosie,” Electric Consumer, P.O. Box 24517, Indianapolis, IN 46224; or use our “Talk to Us” form online.