Article by: Charles Dixon, Ph D
In 1997, I was hired by The University of Tennessee Extension Service as a Wildlife Specialist with wildlife damage management as an area of major responsibility. Tennessee County Agents and farmers identified white-tailed deer as the species most often causing depredation problems to agricultural crops within the state. Furthermore, soybeans were noted as the crop most often impacted. I obtained a grant form the Tennessee Soybean Promotion Board to evaluate the effectiveness of low cost fencing (single strand olfactory repellent and electric fences) in deterring deer damage to highly vulnerable fields planted to soybeans.
In short, the fences were effective in allowing soybeans to be established in these fields and production was higher behind all fences than in control areas that were not fenced. The fences did not stop all browsing on the soybeans, however they did allow soybeans to be produced on fields where deer depredation had removed them from the crop rotation.
In one trial, the entire control area was destroyed and no soybeans were produced while in adjacent fenced areas 22 to 36 bushels per acre were produced during a very dry year. The previous year no soybeans were harvested from this field as the entire crop was destroyed by deer. In another field 95% or more of the first planting was destroyed by deer. The field was subsequently replanted and fenced, and yielded an average of 40 bushels per acre. Differences were less dramatic in other fields, primarily because deer damage was not as severe.
One of the olfactory deer repellents tested, Deer Stopper, was experimental at the time but has now received approval for the retail market. My testing of this product involved constructing a fence, approximately 24 inches high (the approximate height of a deer’s nose), of either rope or ½ inch electric fence polytape, 3/8 inch rebar line posts (placed at intervals of 30 feet) and T-post corners. The fence material was stretched by hand and tied directly to the T-post. It was then secured to the rebar line posts with short lengths of bailing wire. I sprayed a light application of the Deer Stopper onto the rope at construction and then re-sprayed it at monthly intervals until harvest, using a common garden type sprayer. I fashioned a hook and attached it onto the sprayer nozzle to keep the fence material close to the sprayer tip and maximize the portion of repellent contacting the fence material (see figure 1). I preferred ¼ inch nylon rope and the ½ inch electric fence polytape because they were inexpensive, light weight, easy to work with and stayed relatively tight during temperature fluctuations. Deer Stopper adhered readily to all tested fence materials and was not washed away by rain events. The monthly reapplication served to reactivate the fence as the odor from the previous applications had diminished.
You may be asking, how can this Deer Stopper repellent fence help me establish food plots or reduce damage to my garden? After I had success protecting the soybean field I began to look for other applications. I had difficulty establishing food plots for deer on the land that I owned because the deer ate and killed the plants upon emergence. Consequently, I tried the fence around the food plots that I planted with great results. For the first 11/2 to 2 months after the fence was in place deer rarely crossed into the food plots. By that time the plants were large enough that they could withstand browsing, the fences were removed and the deer soon began to feed in them regularly.
Gardens can be protected in a similar manner. Careful timing of fence installation may help keep deer from the plants at the time they are most vulnerable. Construct the fence when the garden plants are most attractive to deer. For example, in the case of sweet corn, deer are not generally a problem until the ears are set and the kernels begin to form. The fence may not be necessary until that time.
There are several basic principals that should be remembered to insure your best chances for success. First, it is easier to prevent deer from feeding in an area than it is to stop them from feeding in the area once they have started. Therefore, the fence should be constructed before damage begins where damage has been a problem in the past or immediately upon observing damage in other areas without a history of deer damage.
Second, the fence’s novelty or unfamiliarity to the deer increases its effectiveness. When a Deer Stopper fence is in place over some weeks or months its effectiveness tends to decline. Respraying the fence monthly will help to reduce this habituation, but as the deer become more familiar with the fence, and they learn that no harm comes to them by approaching it, it’s effectiveness will decline. Therefore, timing is very important. Since you want the fence to be most effective at the time you need it most, it will do the most good, it should be constructed immediately prior to the time that the plants are most vulnerable. In addition, fences should be removed and stored out of the weather when they are no longer needed then reconstructed immediately before they are needed again.
Third, using two or more wildlife damage controls at one time tends to be more effective than using either alone. Therefore, if some other stimuli that tends to help deter deer feeding is added to the Deer Stopper fence, the result may be enhanced (the deer may feed less or avoid the area for a longer period of time). For example, in the case of a garden, the addition of a dog that barks when deer approach (no matter how benign the dog really is) will add impact to the fence and help keep deer away form the area you intended to protect. Even an old fashioned scarecrow could enhance the effectiveness of Deer Stopper fences.
Finally, these fences will not eliminate all browsing but have demonstrated effectiveness at reducing deer depredation under certain situations. Several factors influence their effectiveness given your specific circumstances. Three factors that rank high on this list is the number of deer in the area, the relative amount of alternative foods available to the deer and the palatability of the alternative foods compared to what you are trying to protect. These fences do not present a physical barrier to deer but instead create a psychological aversion. Hunger provides strong motivation that can quickly cause deer to overcome their fear of the fence.
With persistence and the correct tools, food plots and gardens can be grown in areas with high deer populations.