Protecting Young Trees from Trunk Damage

Home Grown  by Keith Reed
A common reason for premature tree failure is from trunk damage caused when a tree is young. For Payne County area residents, this damage is most likely from one of four causes. Two of these are seasonal issues that can best be addressed right now.

Winter injury or sunscald. This is a problem for young smoothed-barked trees like maples. Symptoms are large vertical wounds on the main trunk. These wounds are caused in the middle of winter, when the low winter afternoon sun quickly heats up a very cold tree, causing the plant tissue to rupture. This almost always occurs on the southwest part of the trunk which explains why this is also called southwest injury.

To prevent this damage, protect the trunk with a wrap. There are several products out there that do the job ranging from heavy paper wraps to plastic “candy cane” style wraps. The goal is simply to shade the trunk from the direct sun so something as simple as a piece of ABS drainage pipe will also work. It is very important to remove this wrap next spring as leaving it on during the growing season can cause its own set of problems.

Deer damage. Deer can destroy young trees (of all species) as they work to rub the velvet off their antlers. This activity begins soon. If you are new to the area, this may seem like only a rural problem, but don’t be so sure. Deer are surprisingly common in our cities and towns, especially if you live near a greenway or wooded area. The same products mentioned above will also work for this problem. Installing wire fencing similar to a tomato cage will also do a good job of providing protection.

There are also commercial spray-on deterrents designed to keep deer away, but research has shown these to be less than ideal. If you do use them, pay close attention to the instructions for reapplication of the product.

The other two most-likely causes for trunk damage are human caused. Mower or string trimmer damage is more serious than most people realize and should be avoided at all costs. The best prevention measure here is to maintain a mulched area several feet around the tree. This not only eliminates the need to get close with lawn care equipment, the tree will also benefit from the mulch.

It is also far too common to see irreversible damage caused by failure to remove stakes and guy wires (as well as the products mentioned above) on a timely basis. If a new tree is otherwise strong and healthy, it should rarely need to be staked or braced for more than one year.

Trees are a long-term investment. Taking these steps can go a long way towards insuring your investment continues well into the next generations.

For more information on this or any other horticultural topic, you can contact Keith Reed, the Horticulturist in the Payne County Extension office. Keith can be reached via email at, phone at 405-747-8320, or in person at the Payne County Extension office, located at 315 W. 6th in Stillwater.

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