09/30/1999

Aroma Therapy for Deer Control? Research Shows Deer Repelled by Certain Aromas

AUBURN, Ala.—Having problems with deer in your garden? Try a little aroma therapy – rotten eggs maybe?

Christine Harris, a Ph.D. candidate in Auburn University's Department of Horticulture, has been conducting research on methods to repel deer from gardens and has found that a product made from rotten eggs is one of the most effective options for deer control, at least on ornamental plants.

"Research has shown that the most selective and cost-effective approach to controlling deer is chemical repellency," said Harris. "However, little research has been conducted on the effectiveness of natural chemical products used to repel deer."

Harris, who earned her bachelor's degree in biology from the University of Tennessee at Martin and her master's degree in biology from Austin Peay State University, came to Auburn in 1998 to work on her Ph.D. with Associate Professor of Horticulture Eric Simonne. Simonne had being conducting research on garlic sprays used as natural insect repellents and was interested in learning more about deer repellents as well. Harris volunteered to manage that project for her graduate studies.

Deer damage to gardens and yards has been growing in recent years as deer populations have exploded. The economic impact of this damage has not been estimated in Alabama, but Harris said it is a big problem for homeowners as well as nursery owners.

For Harris' study, deer that were part of another AU wildlife study were given access to plants that had been treated with three different organic products. One was a garlic extract, another a fish oil extract and the third was made of whole egg solids. These substances were applied to vinca, hosta and gomphrena, and deer in the research facility were given access to the plants. Each day of the study, Harris rated the amount of damage done to each plant species in each treatment. According to Harris, the egg-based repellents were the most effective and easy to use of the products she has tested.

"I've tested almost everything on the market," she added, "and the egg-based repellent seems to be the best." Harris has not tried to make her own rotten-egg formula, though she said homeowners could try this. However, she noted that home-made products may be a little less pleasant to use. The commercial product does not have an offensive smell – at least to humans -- but a home-made product may be more odoriferous, she noted.

"It does have a little bitter taste," she said, noting that in the course of her research she has accidentally tasted all the products. "But it's not overwhelming, and when you walk by the plant you don't smell it at all," she said.

The same study is underway on free-ranging deer at the Piedmont Station, an outlying research unit of the Alabama Agricultural Experiment Station that is located in Camp Hill, Ala., to see if deer in the wild react differently to the product than deer in captivity. And Harris currently is conducting a similar test on sweet potato, southern pea and turnip to see if the products also work on vegetable crops. She also is evaluating the length of efficacy supplied by these products last before they must be reapplied.

"Some of the products claim they will last for three months, but we have not tested that yet. The egg-based product has held up well in our tests, though," she added.

She also is interested in learning specifically about plant extracts that may repel deer. "There are certain plants that we know deer will not eat," she said, "and there are some commercial products that have been made of these plants. I plan to test these and eventually make some extracts of my own and try to figure out what compound it is in the extracts that repels the deer. Harris also hopes to do research on large-scale crop production using these organic products.

And Harris also has thinks a slight career change may be in her future.

"When I was in third grade I came home and told my mother I wanted to be an astronaut," she recalled. In fact, that's how Harris became involved in biological studies. Realizing that as an astronaut she would need a strong background in science, Harris began to concentrate on science classes in high school years and on into college. While in college she fell in love with plant biology. Someday, she hopes to find ways to combine her love of space with her love of horticulture and plants. Who knows, she may be the first person to take deer and rotten eggs into space.

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News from:

Office of Ag Communications & Marketing

Auburn University College of Agriculture
Alabama Agricultural Experiment Station
3 Comer Hall, Auburn University
Auburn, AL 36849
334-844-4877 (PHONE) 334-844-5892 (FAX)

Contact Jamie Creamer, 334-844-2783 or jcreamer@auburn.edu
Contact Katie Jackson, 334-844-5886 or smithcl@auburn.edu

09/30/99