Arboretum offers tips for damaged trees

Daily Herald report
Updated 7/11/2011 6:40 PM

When wild weather like Monday's damages your trees, there's a lot more to do than clear debris, experts at the Morton Arboretum in Lisle said.

Plant Information Specialist Doris Taylor of the Arboretum Plant Clinic said there are several important steps to take if high winds rip large limbs from your trees.


Damaged trees attempt to isolate their wounded areas by growing a wall of cells to block possible rot from infiltrating the trunk. But if you leave a jagged wound, rather than creating a clean cut, the wall could be compromised and make the tree vulnerable to diseases or pests, she said.

To cure the problem, the arboretum recommends a three-step pruning technique:

• Cut to remove most of the damaged branch to reduce the weight pulling on the trunk.

• Make a cut beneath the remaining damaged branch, approximately one-third of the way up through the branch. Make this cut between the edge and the branch collar, a swollen area where the branch arises from the trunk.

• Make a final cut entirely through the branch, just beyond the branch collar.

Taylor warns never to cut flush with the trunk, which would cause a very large wound and make it difficult for the tree to heal. In contrast, trees that receive a clean cut develop a hard edge, which is a sign the tree has healed.

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In addition, hanging branches are hazards to people or property and should be pruned as soon as practical. But some jobs are dangerous for average homeowners and Taylor said you should never climb a ladder to prune a tree, especially not with a chain saw.

Similarly, if a tree is blown over or the trunk is so severely damaged that the tree may fall, safety is a primary concern. In those cases, you should call a certified arborist. Such arborists can often save young or small trees -- up to about 15 feet tall -- that are partially blown over.

Lightning sometimes kills a tree outright and other times causes no damage. It sometimes takes a year or two for death to occur. After lightning strikes, prune the tree for safety; otherwise wait until the following growing season to assess damage. Keep the tree well watered and fertilized, Taylor said.

Finally, when a tree is destroyed and you want to plant a new one in the same spot, Taylor said an arborist should remove the old stump. In choosing a replacement tree, select a species that is suitable for our area and would help diversify the landscape.

For free assistance, call the Morton Arboretum Plant Clinic at (630) 719-2424 or email