Division of Agricultural Sciences and Natural Resources
Assessing, deciding and managing storm-damaged trees
Following a storm, land owners should assess the damage and make the decision to attempt to rehabilitate or remove a tree. This decision can sometimes be difficult especially when the damaged tree is a very large, old or heirloom tree.
“It’s often difficult to part with a large shade tree. Be realistic when making your decision,” said David Hillock, Oklahoma State University Cooperative Extension consumer horticulturist. “As a general rule of thumb, if more than 50 percent of the tree crown has been damaged, the likelihood of survival is small.”
Ice storms have a knack for exposing pre-existing problems with trees. A consistent type of damage that greatly impacts a tree’s longevity is when large limbs break, they often peel bark down the trunk of the tree. This leaves a very large wound and opens the tree to infection by plant disease.
“Consider the long-term health of the tree and potential risk from leaving the tree in place,” Hillock said. “If you choose to save a severely damaged tree you’ll need to commit to caring for that tree over many years to come.”
The first and most important step in pruning damaged trees is removing hazards such as hanging limbs, cracked branches and unstable trunks. However, improper care can create hazards in the future.
“Do not top trees. Topping, or dehorning, permanently ruins the structural integrity of the tree,” he said. “Topping will lead to adventitious growth, which is likely to break away from the tree during a future ice or wind storm.”
Not only will this have a negative impact on the structural integrity of the tree, it will lose some visual appeal. Instead, broken limbs should be cut back to a branch that is at least a third the diameter of the branch being removed.
A branch should be cut just outside the branch collar, which is the swollen region where a branch connects to the trunk. Avoid cutting flush against the trunk, as this will create a wound that will not properly seal.
Larger branches should be cut using the three cut pruning method to avoid peeling bark. This process begins with the first cut about six to 12 inches out from the trunk on the underside of the branch, approximately a third of the way through.
Next, cut through the branch just outside your first cut, leaving a stub on the tree. The final step is to make the pruning cut, leaving the branch collar on the trunk.
Homeowners also may experience pine trees that have damaged leaders, which is the central shoot and top vertical branch of the tree. When the leader is broken, subsequent growth of the tree is altered.
“Without a leader, the pine will no longer grow upward, but rather spread outward,” Hillock said. “Sometimes we can try to establish a new leader.”
The first step in creating a new leader is to cut the broken shoot tip cleanly, just above a side branch. After attaching a sturdy stake to the tree trunk and allowing a section to extend beyond the broken tip, the largest lateral or side branch should be secured to the stake.
This will direct the branch upward, and overtime, the lateral branch will become the new leader.
Oftentimes storm-damaged trees are too large for property owners to rehabilitate themselves. If this is the case, a professional arborist should be consulted for the job. The Oklahoma Department of Agriculture, Food and Forestry has a list of certified arborists in its Forestry section of the website, http://www.forestry.ok.gov.
More than 50 fatalities nationwide are reported each year from professionals removing or pruning trees. Needless to say, it is a dangerous job, so the arborist you select should be insured.
With urgent responses and pruning, some damaged trees can be saved. However, a patient will not have a full recovery from a successful knee surgery if dedication to rehabilitation is not practiced.
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