sw tree injury

Southwest Tree Injury occurs during the overwintering of thin barked, oftentimes, freshly planted young trees.

Courtesy/Tom Ingram

I planted a maple tree a few years ago and now the bark is split. What should I do? EH

The damage you are describing is likely what we call Southwest Tree Injury. It’s not called that because the ailment only affects trees in the southwest part of the country, but because it is damage that appears on the southwest side of the tree.

Southwest tree injury occurs during the overwintering of thin barked, oftentimes, freshly planted young trees.

During daylight hours, the winter sun warms the bark which causes it to expand. At night, the cold chills the bark causing it to contract. As this process repeats each day, the bark can be damaged, resulting in a split in the bark. Most trees do not recover from this damage.

You can see trees with this problem all around town, especially in new construction or in parking lots. New young trees are planted in small areas of the parking lot. The heating and cooling of the bark in winter is exaggerated because the tree is typically surrounded by asphalt causing more heat to be generated and reflected onto the bark of the young tree. Southwest tree injury is very common in these situations. The next time you are driving through one of these lots, look at the trees. If they are thin barked trees, they likely will have southwest tree injury.

Certain trees are more susceptible such as cherry, maple, weeping willow, and various fruit trees. However, this problem can be mitigated with a simple strategy.

As we enter the winter season, wrap the trunks of any newly planted thin-barked trees with paper tree wrap. This wrap should not be tight as you want circulation, but you also want it snug enough to remain in place. In the spring, as it begins to warm up, remove the tape. This process should be repeated for at least the first two or three years. After that, the bark should be strong enough to remain unaffected by the changing temperature. Most garden centers should carry this tree wrap.

Once the damage has occurred, there is not much you can do. The tree will try to heal the gap but is rarely successful due to the size of the damage. These gaps will make the tree more vulnerable to disease as the inner layers of the tree are exposed. But the good news is that you can avoid southwest tree injury with a little effort and a roll of inexpensive paper tree wrap.

You can get answers to all your gardening questions by calling the Tulsa Master Gardeners Help Line at 918-746-3701, dropping by our Diagnostic Center at 4116 E. 15th Street, or by emailing us at mg@tulsamastergardeners.org.

Nicole Marshall Middleton

918-581-8459