Deer are damaging crop fields to the extent that it affects yield, but the solution to the problem may be more than a bow and arrow.

For the past six years, portions of the University of Missouri Bradford Research Farm just outside of Columbia have had a large deer population. To the point where soybeans aren’t harvested, research is compromised or both.

There are a lot of claims that deer repellents work. “Some people swear by using them,” says Kevin Bradley, MU Extension weed scientist. “So, we decided to gather some university data on the use of these products.”

This summer, Bradley tasked Grady Rogers, a graduate student from Kentucky, with a deer repellent study.

Nuts and bolts of research

Rogers is looking at two locations to see if using repellents can be successfully tank-mixed with common herbicide treatments and also to save yield, particularly in soybean fields, by reducing deer feeding.

“To keep the wildlife away you need some pretty powerful stuff, usually some pretty pungent stuff,” Rogers says. “These products that we’ve been testing don’t disappoint at all in that arena.”

He selected four repellents — Liquid Fence, Bobbex, Hinder and Plantskydd. He analyzed some of the ingredients on the list and found them interesting. “There are things like eggs, lots of oils and garlic,” he says. “The Plantskydd product contains dried bovine blood.”

Rogers also included the herbicide Select Max, which came at the recommendation of a farmer.

The study required application of the repellents as a tank-mix additive with soybean herbicide treatments like Liberty, Roundup, Prefix and Dual II Magnum.

The products were sprayed up to three times throughout the season. Bradley says most of the labels on these products recommend spraying numerous times throughout the season at two- or three-week intervals. “I’m not sure how that would work out financially, but at this point we’re just trying to see if either of these products can be effective,” he adds.

Initial findings

Rogers, along with fellow graduate students, conducted deer feeding counts weekly throughout the months of June and July. “We look at what’s been newly browsed from the week before,” he notes.

They assessed the percentage of feeding. Preliminary data shows that one week after treatment, all of the repellents worked similarly and reduced browsing. “But after that, it really just goes away,” Bradley adds.

This is only part of the story.

After fall harvest, Rogers will gather more data to determine what effect, if any, the deer repellents have on productivity and if they affect the efficacy of herbicides.

Bradley says farmers should stay tuned as results of the deer repellent study will be part of the winter MU Crop Management Conference, Dec. 6-7 in Columbia.