Thousands of trees each year are damaged due to storms. Also, many trees have been stressed due to drought for many years. Tree damage to property in Georgia can easily reach over $10 million annually. Probably one of my top calls are from clients worried about certain trees on their property and what damage that tree can do if it came down. I can give my opinion, but many times the homeowner needs to get a certified arborist to do a hazard assessment of the tree. Today, will share information on understanding and preventing storm damage on trees from Dr. Kim Coder, Professor Silvics/ Ecology with the UGA Warnell School of Forest Resources.

First, remember that trees are designed to adjust to what Dr. Coder calls “wind loading”. Wind loading is a straight wind from one direction applied equaling over the stem, branches and tree leaves. “Wind release” according to coder is the removal of wind loading when the crown and stem snap back into a normal position. When it is windy, there are gusts and calm periods. This will load and release the tree. Wind will cause changes in the woody material developing in the stem. Coder states that if a wind continues from one direction all the time, hardwoods will develop extra strength on the wind side of the tree. In pines, the extra strength will develop on the side of the stem opposite the wind. If the winds are not damaging enough to blow the tree completely over, the tree will develop what we call “wind firmness” over multiple growing seasons. Finally, “wind firmness” is directional. Trees that grow under a constant wind from the north can be damaged from a wind that comes from the east. Coder says that most open-grown trees will develop solid “wind firmness” in all directions over time.

What are the most common types of storm damage? There are seven main types. Blow-over is when a tree falls due to high winds. Past problems can make the tree more susceptible to wind. Stem failure is a tree has many old wounds. Trees do not heal wounds. Trees will grow over the wound and seal it off.

These areas are weaker and can make the structurally not as sound. Heavy crown damage is due to a tree having a heavy crown and not able to handle big quick wind gust and then calms. Crown twist is when trees have more lopsided crowns. More wind loading on one side of the crown can produce a torque or twist on major branches and stems. Root failure can happen from multiple issues such as disease and construction damage. Roots are the anchor for the tree so a compromised root system can lead to damage in a storm. Branch failure where branches are poorly attached can lead to issues in storms such as overloading with ice. Lightening damage can lead tissue damage of the tree, water loss and then lead to more pest damage.

Preventing storm damage is important so here are a few tips that can help. First, let trees adjust to the wind environment. Do not tight stake a young tree. If staking, tie the tree loose enough so it can move and bend in the wind. All added tree support should be removed after 5-7 years. Conduct proper pruning techniques. You can prune out limbs before they become larger than one inch in diameter to help develop the tree structurally. Do not damage the branch collar. You can easily find diagrams for proper pruning. It is suggested by Coder to eliminate co-dominate branches. Prune forked branches and branches that arise opposite each other on the stem early. Cut one side off now to prevent losing the whole tree later if it splits in a storm. Trees such as ash and maple have opposite branching pattern.

Proper branch training is important to have a long-lived tree that is fairly storm resistant. Do not over-fertilize with nitrogen or over-water. This can increase the crown size and decrease the root zone area. For more tips on damage prevention, contact Gordon County Extension at 706-629-8685 or email gbowman@uga.edu.