When we think about wildlife damage to landscapes and agricultural plantings, we are probably most familiar with deer feeding and browsing damage, especially in the winter and early spring. A hungry deer in the winter will eat about any vegetation and can put away four pounds or more of twiggy branches a day. Damage to trees and shrubs can be extensive, affecting plant shape and exposing bare wood to disease and insects. Mice and rabbits also inflict feeding damage to tree trunks and small plants, sometimes girdling them at or near the ground level.
The fall months bring another type of deer damage associated with the fall mating "rut". From early September through November male deer are looking to clean their antlers of summer velvet, while at the same time marking territory during the breeding season. In addition to rubbing antlers against trees to remove velvet, buck deer assert themselves by thrashing and battering the tree for noise effect, and coating the twigs and bark with scent from glands in their face and underbody to mark territory. Young trees, especially those 1 to 4 inches in diameter with smooth bark are especially susceptible, such as maple, magnolias and birch. Young, soft-wooded, pliable saplings, especially pine and bald cypress are also targets, and can quickly be reduced to stubs. Rubbing continues even after the velvet is removed, darkening antlers over time from plant sap.
Tree damage involves shredding of bark from a foot or so above the ground, to three to four feet up, exposing underlying wood. If rubbed all the way around, the trunk can be effectively girdled. If small trees are bent over by the deer, main leaders and smaller limbs can be broken off. Usually the damage is done over a 24 hour period. Because this is also a territorial action, the buck may revisit trees they like in subsequent years. Always keep in mind a buck in rut is an unpredictable animal. It has an agitated and angry appearance, and will often stand its ground and not be afraid. With its sharp antlers it is a clear danger, and challenging it or attempting to scare it away may result in an attack.
To address tree damage, trim loose, shredded bark where it's not connected tightly to the trunk. Where the bark isn't loosened around the circumference, the tree might heal and continue to develop. Fully girdled trees will die. If limbs have been broken, then the tree's structure may be altered. Prune broken branches to a strong side shoot or main branch or trunk. Look for an undamaged shoot close to the top of the tree that might be trained as a new leader if the tip has been broken off. If nothing is done, the tree will re-sprout in the spring below the damaged area, and become shrubby in growth and appearance. Over the course of the growing season, new bark will develop to cover exposed wood.
Should the tree recover, take steps to protect it next fall by wrapping trunks with plastic trunk wraps, strips of rubber tubing, or hardware mesh. One or two steel posts set next to the tree are very effective in deterring rubbing action. Flared bases on posts should be set in-line with the trunk to reduce root damage when driven in. Posts are especially effective in protecting smaller trees, and light gauge steel types 4 to 6 feet long can be used. A temporary fence can also be constructed around larger trees from September through November using woven fencing or chicken wire.
Bars of soap hung in the tree and bags of human and pet hair have varying degrees of effectiveness in repelling deer, and work especially well to prevent browsing on young fruit trees. Pre-formulated and home-made spray-on repellents are one of the most common deer control techniques used for woody plants. Their success is often rated by how much reduction there is in the feeding, since they often will not eliminate it. Keep in mind the effectiveness of repellents is based on several factors. Rainfall and moisture dissipate some materials, so reapplication is needed. If food sources are extremely scarce, deer may simply ignore the repellents, despite the taste or odor. A deer in rut will likely disregard it altogether.
Deer can do significant damage to new and young trees being established in the landscape. Take steps this fall to protect young trees from rutting bucks, and correctively prune trees that become damaged. Pay special attention to them the following year, as they may be revisited and damaged further. For additional information on wildlife control, visit the University of Illinois website: Living With Wildlife in Illinois: http://web.extension.uiuc.edu/wildlife/ and the Illinois Department of Natural Resources at: http://dnr.state.il.us/
Source: Anthony Bratsch, Extension Educator, Horticulture (Serving East-Central and Southeastern Illinois), firstname.lastname@example.org
Pull date: November 15, 2008