In fall or winter, homeowners often discover young trees whose thin bark has been damaged by deer rub. Some trees may have patches where bark hangs in shreds, exposing the underlying wood; in others, the bark may be rubbed away all around the trunk.
“Whether the tree can recover depends on the extent of the damage,” said Sharon Yiesla, plant knowledge specialist in the Plant Clinic at The Morton Arboretum in Lisle. Male deer rub their antlers on trees’ bark in fall to remove the fuzzy velvet that covers them when they are newly grown. “When the velvet is ready to come off, it gets itchy, and a deer will use a tree to scratch,” Yiesla said. The rubbing also serves to mark a male deer’s territory for the early winter mating season.
In late winter, when the deer is ready to shed his antlers and begin growing a new set, he may also use a tree to knock the old ones off.
Most damage is done to the trunks of young trees at a height of between 18 inches and 5 feet. “Deer also rub their antlers on older trees, but their thick, hard bark can stand up to it,” she said. “The young trees are vulnerable because their bark is thin.”
Bark is a vital organ to a tree. Just beneath it are important layers of cells where water and nutrients flow between the leaves and the roots. If those layers are shredded, the flow is cut.
When deer only shred bark in a patch or on one side of the tree, there is a good chance the tree can seal over the wound and survive. “The bark will develop an unsightly scar, but the tree may still be able to manage with the undamaged part of its bark,” Yiesla said.
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In the worst cases the bark is torn up all the way around the trunk, completely severing communication between roots and leaves. “That tree can’t heal,” she said. “There’s no way it can survive.”
To help a tree rubbed in only a patch, Yiesla suggests carefully trimming the torn bark around the damage with a razor knife or sharp pruners. Remove the shreds and make the wound into a rounded or oval shape if you can do it without enlarging the wound. Prune out any branches that have been broken.
Do not apply tar, wound sealer or any other substance to the wound. “Those will prevent the tree from using its own healing capabilities,” Yiesla said.
Wrapping the damage in burlap or tape is also a bad idea because it will trap moisture in the unprotected wood and increase the chances of disease or decay. “Leave the wound open to the air,” she said.
How can you prevent deer from damaging the bark of young trees in the first place? It takes a physical barrier. One possibility is an 8-foot fence. You also can make a tube of sturdy wire mesh such as dog fencing around each young tree’s trunk. Be sure it is not so tight that it damages the bark but is tall enough that a deer can’t reach over it.
Plastic tree guards are also available. Choose one with plenty of openings for air circulation, and remove it promptly in early spring.
“Deer live alongside us in many communities,” Yiesla said. “We should know about their behavior and make a habit of protecting our plants.” To learn more about animal damage in the garden, see mortonarb.org/animal-damage.
For tree and plant advice, contact the Plant Clinic at The Morton Arboretum (630-719-2424, mortonarb.org/plant-clinic, or plantclinic@mortonarb.org). Beth Botts is a staff writer at the Arboretum.