The splendor of fall color on deciduous trees is a beautiful indicator that winter is coming. In the months ahead, the outdoor landscape will experience freezing temperatures, piles of snow, and an abundance of dormant or dead plants. For the animals left to survive the winter season, the trees and shrubs in our landscape may be the only source of necessary sustenance available. Left unprotected, trees and shrubs may sustain significant damage from snacking critters such as rabbits, deer, mice, and voles.
Anatomy of a tree trunk
In woody plants, tissues responsible for the exchange of water and nutrients between the canopy and roots are located just below the bark. This living layer includes the phloem, which is responsible for the transport of sugars from the leaves to the roots, the cambium layer that grows new wood, and the xylem that transports water from the roots to the canopy. When thin-barked trees or shrubs sustain damage to the bark, it is likely that this living layer of tissue will also be wounded.
Damage to this layer of living material can lead to impaired vascular function, reduced structural integrity, and a wound that is incapable of sealing, exposing interior heartwood to pests and pathogens. Once damage has occurred, there is little that can be done to protect the tree or support recovery at the wound site. Long-term impacts may include stunted growth, increased susceptibility to pests, pathogens, and environmental stress, and a shortened lifespan. It is best to take actions to prevent damage.
Rabbits, mice, and deer …Oh my!
During the growing season, rabbits primarily eat herbaceous plants such as grass, lawn weeds, flowers, and leafy greens. When preferred options are unavailable, rabbits will feed on young twigs, branches, and tender bark of trees.
Mice and voles are small rodents that feed primarily on green vegetation, including grasses, herbaceous plants, and seeds. Like rabbits, during the dormant season, mice and voles will consume bark, twigs, and roots of woody plants when more desirable food sources are unavailable.
Deer consume a variety of plants during the growing season including browse (leaves, twigs, buds, and bark of woody plants), forbs (herbaceous flowering plants), grasses, mast (seeds), mushrooms, and lichens. Once the landscape goes dormant, many of these food options are reduced or unavailable. Evergreens retain leaves throughout the winter, making them more susceptible to deer browse, although, when necessary, deer will feed on other plants to survive winter.
During late summer and early fall, deer will use trees and woody plants to rub the velvet off their newly developed antlers. This rubbing can damage trees by breaking limbs and removing bark.
Prevention is the best medicine
The most effective way to prevent animal-caused damage is to prevent access. To adequately protect plants from rabbit damage, install a fence barrier around the plant to be protected (chicken wire or hardware cloth is recommended). The fencing needs to be tall enough to prevent animals from being able to climb or reach over the top; 24 to 36 inches is recommended. Secure the fence to the ground using anchoring pins to prevent rabbits from crawling under the fence.
Singular tree trunks can be protected with plastic or vinyl tree guards. Guards need to be larger than the trunk to minimize the risk of damage from the method of protection.
Given the opportunity, mice and voles will over winter in naturalized areas, deep mulch, or in ornamental grasses and groundcover. To minimize the risk of these rodents nesting near prized trees and shrubs, remove the vegetative habitat and pull back mulch from trunks in advance of winter. Additionally, use physical barriers such as tubing around the trees like recommended for rabbit exclusion. Bury the tube two to three inches below the soil surface to prevent animals from crawling under and gaining access to the tree.
Exclusion fences for deer need to be well constructed to prevent deer from damaging or breaking the barrier, and need to be taller to prevent deer from jumping over the fence. An eight-foot fence height is the minimum recommended for excluding deer. If deer have a running start, it deer may be able to clear a twelve-foot fence. Electric fences like those used for livestock may provide some protection if the deer encounters the wiring. Specimen trees can be protected with a five-foot-tall wire tube.
Throughout the winter, check the protection to ensure that it continues to protect the tree or shrub. And check the plant material for damage and make changes if necessary. Look for damage caused by animals or by the protective materials.
When spring arrives
Tubes or wraps used during the winter months must be removed during the growing season to prevent injury, such as restricting growth or damage.
Open-weave fencing that is anchored away from the tree trunk or shrub can remain in the landscape for protection if necessary.
Good Growing Fact of the Week: In addition to protecting trees from animal damage, make sure trees are well hydrated as they enter dormancy to help minimize desiccation injury. Deeply water trees and shrubs until the ground freezes.
Thank you for reading!
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MEET THE AUTHOR
Emily Swihart is a horticulture educator with University of Illinois Extension, serving Henry, Mercer, Rock Island, and Stark counties since 2021. Emily provides horticulture programming with an emphasis on the home gardener, the urban forest, native plant ecosystems, and landscape design. Additional responsibilities include supporting local county Master Gardener and Master Naturalist volunteers - providing training, continuing education, advanced training, and their involvement in seasonal events and community outreach programs.