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Oh, Deer! Managing Deer In The Garden
The most effective way to reduce deer damage to ornamental plantings is to use an integrated pest management approach. This approach includes the use of vegetation management, repellents and fencing, if needed. This article discusses the use of repellents.
Repellents can reduce plant damage by modifying the feeding behavior of deer and are most effective when applied before feeding damage occurs. Three types of repellents have been proven to be effective in reducing deer feeding damage. These repellents are contact repellents and odor (or area) repellents and a new class of repellents that work by both odor and taste.
Contact repellents are applied directly to plant materials and repel by foul taste. This class of repellent generally works best on dormant trees and shrubs and would require frequent reapplication to protect new growth. Contact repellents should never be used on food crops.
Many "home remedy recipes" are available to be mixed for use as a contact repellent. The ingredients usually include hot peppers, soap and eggs. While these "recipes" may work, there is significant possibility for damage to the plants caused by improper use of the "ingredients". For contact repellents, it is best to rely on proven commercial repellents.
One of the best contact repellents available is Deer-Away. This formulation of putrescent egg solids was developed for the Weyerhaeuser Corporation to protect saplings on their tree farms. It is reported to be 85% to 100% effective if applied properly. The labeling on Deer-Away does caution against possible burn on new growth. This burn potential and the two-month average effectiveness make Deer-Away ideal for dormant season use. Deer-Away is sold in liquid form to be diluted and applied. It is also sold in a powder form that can be applied when the temperature is below 40 degrees.
Odor/Area repellents may be applied to the plants to be protected or may be applied near these plants. Large areas can be protected for a relatively low cost by applying an odor/area repellent at the border of the plantings. There are many odor/area repellents available including human hair, animal hair, animal urine and bars of soap. Unfortunately, these repellents have inconsistent results and usually lose their effectiveness quickly.
The most effective commercial odor/area repellent available is Hinder. Hinder can be applied directly to food crops and will not burn new growth if used correctly. Effective for about two weeks, depending upon weather and application technique, Hinder is less expensive per application than other commercial repellents. Low burn potential and relatively low cost make Hinder an excellent growing season repellent.
The newest class of repellents combine odor and taste to effectively reduce feeding damage. Deer Away is now available in a ready-to-use formula made of chili pepper, oil of mustard, vegetable oil and lemon. This formula is quick and easy to use and can safely be applied to new growth, but must be reapplied every seven to ten days.
The newest commercial repellent available is Tree Guard. This promising repellent is a blend of Bittrex, an extremely bitter chemical, and latex, which resists weathering. In addition, Tree Guard has an odor repellent and has performed well in dormant and growing season trials. It is registered for use on any nonfood plant. Depending upon application and weather conditions, Tree Guard is effective for 2-4 months.
Things To Remember About Repellents
- Repellents do not eliminate browsing; they only reduce it.
- Many repellents will be washed off in rain and will need to be reapplied.
- Repellents do not eliminate deer rubbing, but may reduce it by keeping deer out of an area.
- Repellents work by altering behavior and therefore work best before feeding habits are established. Deer establish feeding habits in late fall and spring.
- Availability of alternate food sources can impact the effectiveness of repellents. Remember that a hungry deer will eat anything.
- Deer tastes and preferences vary. Therefore, a repellent that works in one area may not work in another area.
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