Q: A branch broke off my tree during a storm. What do I put on tree to protect it from disease?

— Jen from North Benton

A: While it is great that you are thinking of tree health, there is nothing you should put on the tree wound to help protect it. There are sealants on the market but none of them are recommended.

Many people think treating injuries to trees is like treating injuries to themselves or other animals. Putting something over a wound to heal is very different in trees than in people or animals. Trees respond differently to injuries than we do.

Trees don’t heal, they seal — although is OK to use either term.

Any injury to a tree, such as a broken limb, is a potential entry point for diseases or pests. The tree protects itself from these dangers by isolating the damaged area through physical and chemical processes. These processes result in callus tissue developing at the edge of the wound and gradually expanding toward the center. This process is called compartmentalization

Scientific studies have been conducted on effectiveness of tree sealants. These are the black tar type sprays you find in some stores. None of the studies have found any benefit to the tree from the use of these products. In fact, use of some types of sealants can inhibit or delay the tree’s natural recovery processes by trapping water inside the wounded area (under the sealant).

If the limb on your tree has not broken completely off from the tree’s trunk, prune it back to the collar of the limb. The collar is the swollen area at the base of the limb. Sometimes, this area looks like wrinkles in the bark. Think of those as the smart cells that grow callus tissue.

If you don’t feel conformable pruning the limb yourself, or if you can’t reach it, we recommend contacting a certified arborist. Certified arborists are members of professional organizations such as ISA — the International Society of Arboriculture. They are knowledgeable on all aspects of tree care and have access to current technical information.

Trees have natural resistance mechanisms to fight insect attack or disease when injured. Pruning sealants are unnecessary and covering wounds with sealants inhibits the tree’s natural recovery processes.

The ONLY exception to the rule is the pruning of oak trees in the summer. These wounds can be sealed with latex paint to avoid infection from oak wilt disease.

To learn more about proper pruning and care of tree wounds, go to http://go.osu.edu/treewounds.

Sprague is an Ohio State University Mahoning County Extension Master Gardener Volunteer. Visit the Plant and Pest Clinic or call the hotline at 330-533-5538 from 9 a.m. to noon Mondays and Thursdays for help with plant issues, soil testing and insect identification. For details, visit go.osu.edu/mahoningclinic.