Gardening with Allen: Tree bark damage stunts growth

I am considering the purchase of a home that has a nicely maintained landscape. However, some of the younger trees have a limited number of small leaves. I noticed what look like cuts on the bark near the ground. Is this damage permanent, or will they outgrow it?

Bark damage to tree trunks is usually caused by line trimmers or lawn mowers hitting the trunk. Trees can repair this damage if it has not gone too far. Smaller than normal leaves is an indication that damage is serious and could threaten the life of the tree.

Many people do not realize that the bark of a tree is much more than a protective layer. The inner bark contains tube-like cells that carry food manufactured by the leaves to the tree roots. When bark is damaged, it reduces the amount of food that reaches the roots. This limits root growth, which in turn limits the amount of new leaf growth that roots can support.

Trees can repair and replace the damaged bark. However, if the bark is cut completely through, all the way around the trunk, roots will gradually die, followed by death of the top. When damage is severe enough to cause smaller than normal leaves or stunting, it is close to the point of no return.

The best solution is to create a circle without grass growth around each tree or group of trees and shrubs. This not only prevents damage from mowers and trimmers, but creates an area without competition for water and nutrients. Grass roots are fibrous and intercept much of the surface water and nutrients before they reach tree roots. Grass plants also produce a chemical that reduces growth of nearby plants. This competition-free area can double the growth rate of young trees and shrubs. After damaged trees have had several weeks or months to produce new bark they will probably respond to fertilizer and produce normal top growth.

There are several ways to keep this area weed-free besides pulling or cultivating. A 2-inch layer of bark dust or other organic matter such as composted leaves and grass clippings will reduce new weed sprouting by 90 percent. Most weed seeds need light in order to germinate. The mulch prevents most of the light from reaching the soil surface. Weed barrier fabric placed on the ground before covering with mulch will eliminate 100 percent of the light and also be a physical barrier to weed growth. Steel or plastic edging materials can prevent grass from growing back into this area.

Granular and liquid weed killers and weed preventers are also available to keep this area weed free.

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