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Deer Repellents

Now is a critical time to protect your plants from damage. Learn which repellents work best.

Deer Damage
Deer are very active now. They can destroy plants by mutilating bark and feeding on lower limbs.
Deer hunting season is upon us and the hunted critters are full of energy. This is a critical time to protect your plants from rutting bucks and other deer looking for a snack. 

Deer bucks are scraping trees to remove the velvet from their antlers. They do this to mark their territory and to attract females. This scraping destroys a tree’s bark and vascular rings (see photo on bottom left). This damage will severely stunt or kill a tree.

Deer are more likely to feed on trees now as berries, grass and other food sources decline.

The most reliable option to prevent damage from a deer is to kill it. The second best option is a physical barrier. An 8-foot tall fence is recommended, preferably electrified. Both of these options are impractical in most cases.

That leads us to repellents. Sometimes repellents work and sometimes they don’t. Sometimes we think they work and they don’t; that’s why university trials are more useful than anecdotal stories.

For example, let’s say a deer munches on your apple tree. Your friend tells you that if you hang bars of soap on the tree, the deer will go away. Sure enough, after you hang a few bars of soap on your tree, you never see damage again.

You think the soap solved the problem. What you don’t know is the deer that munched on your tree got ran over by a truck later that night. The soap never made a difference.

Scientific studies have been conducted to develop reliable strategies to repel deer. The most effective repellents are sprayed directly on the plants to be protected. Sprays applied on the ground along the perimeter of the site are less effective.

Deer repellents have a limited time of effectiveness. In most cases, repellents need to be applied on a regular basis and when new plant growth appears. Follow the instructions on the label.

Repellents that induce fear in deer and generate a sulfurous odor are effective. This includes products containing decaying animal proteins such as eggs or slaughterhouse waste. Deer readily sense this odor and may fear a predator is nearby. Such products include Deer Away, Liquid Fence and Plantskydd.

Repellents that cause pain, such as hot pepper sprays, are effective at maximum levels of concentration.

Repellents that contain bittering agents (denatorium benzoate) are less effective. Ropel is one such product. These products have to be tasted to work, which means the plants must be at least slightly damaged to prevent greater damage.

Repellents such as bars of soap or bags of hair are less effective.

Some trees and shrubs are more subject to damage than others. Deer love to eat apple, linden and arborvitae (see photo on bottom right). They generally dislike prickly plants such as hawthorn, Russian olive, barberry, pines and spruces. Deer do not like ash and lilac, the most popular tree and shrub in our state, respectively.

Written by Tom Kalb, Extension Horticulturist, North Dakota State University. Published in the NDSU Yard & Garden Report, November 7, 2016.  

Sources:

ICWDM (Internet Center for Wildlife Damage Management). 2008. Understand the strengths and weaknesses of repellents before you buy the hype. http://icwdm.org. University of Nebraska: Lincoln.

Swift, C.E. and M.K. Gross. 2013. Preventing deer damage. Fact sheet 6.520. Colorado State University: Ft. Collins.

Trent, A., D. Nolte and K. Wagner. 2001. Comparison of commercial deer repellents. USDA National Wildlife Research Center - Staff Publications. Paper 572. DigitalCommons @ University of Nebraska: Lincoln.

Photos were made available under Creative Commons licenses specified by the photographers: Julie Falk; David Mooter, Prairie Silvics, Bugwood.org; and Rebecca Finneran, Michigan State University Extension.

The information given herein is for educational purposes. References to a commercial product or trade name are made with the understanding that no discrimination is intended and no endorsement by the North Dakota Extension Service is implied. 

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