I just moved from Arizona to this area, and a neighbor advised me that deer were a problem in the neighborhood and that I need to protect my plants from them. What does this mean?
— Sasha Black, Northbrook
Deer can do a lot of damage to area gardens from feeding during the growing season and rubbing trunks in the fall. I live in Highland Park with a fenced backyard, and I had a significant buck rub on a clump-form serviceberry about four years ago. If your home is near a forest preserve or other open green space, your chances of having issues with deer will be greater. Try spraying a repellent on any plants you observe being browsed during the growing season. Any damage you see may also be caused by rabbits, which have been a significant problem for many gardeners this year. I have seen several perennial gardens completely eaten by rabbits this summer. This can be incredibly frustrating for anyone tending a garden.
Garden staff has begun installing tree protection for deer rubs, and we recommend you do the same if you have any young, smooth-barked trees. Bucks can cause significant damage to young trees in the fall by rubbing their antlers on trunks. Male deer do this to clean their antlers of summer velvet from early September through November while also marking their territory during the breeding season. The first week of September is a good time to install deer protection. Bucks may repeatedly strike trees for the noise effect, showing dominance and intimidating other bucks. They coat the twigs and bark with scent from glands in their faces and underbodies to mark their territory. Trees that are 1 to 12 inches in diameter with smooth bark — like maples, lindens, birches, and magnolias — are most likely to be damaged by deer rubs. Larger trees with smooth bark as well as clump-form trees can also be damaged. Unfortunately, buck territories currently include many home gardens with young trees.
The damage to trees from buck rubs comes from the shredding of bark from a foot or so above the ground up to 3 to 5 feet up the trunk. Young trees have very thin bark that offers no protection from such damage. Usually, the damage is done over a 24-hour period. The tree’s vascular system — which is just below the bark and transports water, nutrients and food between the roots and leaves — gets damaged and the underlying wood is exposed. If rubbed all the way around, the trunk can be effectively girdled, which can lead to the eventual death of the tree in one to three years. If the damage is mostly located vertically on the trunk and does not go all around the trunk, the tree can survive, although it may die on the side where the damage occurred.
Protect the trunks of your trees from the ground to about 6 feet up the trunk. Wrapping with burlap or paper tree wrap does not provide enough protection for deer rubs, but it can provide some protection from rodents feeding on the lower trunk in the winter. Try wrapping your tree trunks with a sturdy wire mesh available at hardware stores. Use zip ties to secure the wire mesh around the trunk of the tree. Chicken wire usually works too, although I have heard about nearby gardens where aggressive deer tore chicken wire off the tree and left significant damage to the bark. There are plastic tree wraps that should also work. Surround a small tree with a 6-foot-tall barrier of hardware wire mesh supported by fence posts if you are unable to wrap the trunk. Deer repellant is not usually effective in controlling buck rubs. You need to get a sturdy physical barrier around the trunks of your trees to prevent damage from buck rubs.
Trees can heal after a surprisingly large amount of damage. Trim off any loose, shredded bark where it’s not connected tightly to the trunk. If possible, cut the wounds into an elliptical or football shape to help the tree recover more quickly, but do not dramatically enlarge the wound to do this. There is no need to use wound dressing or to wrap the damage. Smooth edges heal better than the ragged edges left from the deer rubbing. Prune back broken branches as needed. Small clump-form trees can be ruined if too many branches are broken.
Deer will browse yews and arborvitae, so you may need to protect these plants up to about 6 feet too, as deer can ruin them over the course of winter. Chicken wire or a plastic garden netting works for this, and the netting is usually easier to apply.
For more plant advice, contact the Plant Information Service at the Chicago Botanic Garden at plantinfo@chicagobotanic.org. Tim Johnson is senior director of horticulture at the Chicago Botanic Garden.
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