As afternoon storms become a regular occurrence, thoughts turn to the trees around our home. You may be wondering if they are safe, or if they can hold up against the wind of a thunderstorm, tropical storm, or even a hurricane. While there is no “risk free” tree, the tree can provide signals, or clues to any defects it may have. A tree does not have to be dead to have structural problems. An observant homeowner with a little knowledge can recognize common tree defects and have a qualified professional address them before damage occurs..
Failure Categories
Most property damage from trees during storms occurs because of some sort of failure in the structure of the tree. Tree failure falls into three categories: branch failure, trunk failure, and root failure. A periodic tree inspection of the branches, trunk, and root area can reveal problems before they become major ones. To find an ISA Certified Arborist to help with the tree inspection go to https://www.treesaregood.org/findanarborist/arboristsearch.
Branch Failures
The most common type of tree failure is a branch failure. This is also the easiest type of failure to prevent. When you are out in your yard, look up. Take note of any large dead branches. While a small amount of deadwood is to be expected, large dead limbs can cause damage and should be removed.
How the branch is attached to the tree is also important. How the branch attaches to the tree is also important. Observe how the major branches attach to the
trunk. If the attachment of the branch looks like a “V” rather than a “U”, it is a weaker branch attachment. The reason V-shaped branch attachments are a problem is that bark on bark attachment weakens the attachment. This condition can be even more of a risk when the tree has more than one trunk. Multi-trunked trees are especially prone to splitting apart because of poor branch attachment.
When maintaining your tree, how your trees are pruned is just as important as if they are pruned. A myth I often hear is that arborists should thin out the tree canopy so that wind blows through the branches instead of against them. While it sounds reasonable, research from the University of Florida, that looked at how trees handled hurricane force winds, disproved this assumption. The study showed that improper pruning by thinning out interior branches and raising the crown through the removal of large lower limbs and resulted in more damage to the tree during windstorms. Properly pruned trees had considerably less damage than unpruned and improperly pruned trees. Properly pruning trees by using reduction cuts to shorten overextended branches and structural pruning resulted in trees that resisted wind better, and therefore received less damage.
Trunk Defects
Trunk defects are a little harder to detect than branch defects. The most obvious type of trunk defect is a cavity. An arborist should inspect large cavities with decay. Any vertical crack in the trunk of the tree that goes into the wood of the tree is a warning sign of structural problems and a horizontal crack is a sign of imminent trunk failure. Any mushroom or mushroom like fruiting structure coming out of the trunk of the tree is a sign that the tree has internal decay. You should have your tree inspected by a tree professional if you have cavities, mushrooms, or cracks in the trunk of your tree.
Many large older water oaks and laurel oaks seem to inherently have internal decay. Without further testing, no one can determine how much of the tree structure decay has lost to decay. Some arborists are very good at using a low-tech rubber mallet to determine the extent of internal defects while other arborists in our area have specialized equipment such as resistographs, and shigometers that can help determine the extent of decay. At the present time, there is no method to fill cavities or decay in trees that is effective in restoring lost structure back to the tree. The arborist inspecting the tree may recommend pruning or cabling to relieve stress on the trunk, however if the defect in the trunk is serious, removal of the tree may be the only means to solve the problem.
Root Failures
Even though most roots are underground, many root defects can be detected with a little inspection. The part of the root system that bears most of the load in holding the tree up is the root flare. If you picture the tree as a wine glass, the root flare is the base of the wine glass. The root flare should be readily visible for inspection. Many trees have had their root flares covered by soil during construction or landscape activities. Do not form mulch volcanoes by putting mulch over the root flare and against the trunk of the tree. Both situations are bad for the tree because it buries the roots and promotes disease. It also makes inspection of the root flare difficult. If the root flare of your tree has been covered by soil, or mulch, it is important to uncover it for a proper inspection.
As with trunk defects, look for any cavities at the base of the tree, or mushrooms originating from the base or roots of the tree as a sign of possible root decay. Any damage to the root flare by construction, or other means, is a cause for alarm. Recall the wine glass analogy and imagine how unstable the wine glass would be if part of the base were gone. Finally, the last step in inspecting the roots is to step back away from the tree and look at the uppermost branches of the tree. If they are bare, or not as full as the rest of the tree crown, it may indicate root problems. A Certified Arborist should inspect the tree if you suspect any problems with the root system.
There is no way to fully eliminate the risk of a tree falling and causing damage in a storm. Homeowners can significantly reduce the risk with regular inspection of their landscape, by identifying defects in their trees and taking care of them before they become a problem. You can find more information about trees and storms on the University of Florida ‘Ask IFAS’ website at https://ask.ifas.ufl.edu/topics/hurricanes.
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