For Maryland crop producers, deer damage is more than a nuisance; it’s a critical issue that costs farmers millions of dollars in lost yield each year. To help growers protect their crops, University of Maryland Extension (UME) wildlife specialist Luke Macaulay developed The 4 Pillars of Managing Deer Damage, a comprehensive guide built on years of field research and producer interviews.
While placing a dollar value on deer damage is difficult due to variable effects on crops like fluctuating weather and soil conditions, Macaulay isolated the effect of deer by using deer exclosures to compare soybean production inside protected areas with fields in areas accessible to deer. “There is a lot of variability, but ultimately there are significant yield reductions in some of these situations, so it’s a real problem,” he said, “The losses are real – it’s substantial.”
Funded by the Maryland Soybean Board, Macaulay's research focused heavily on soybeans because they offer high-protein forage that deer crave. Indeed, a 150-pound deer can consume roughly 9 to 12 pounds of vegetation per day.
For a mature soybean plant, that amount of feeding may be manageable, but for a six-inch seedling, repeated grazing can quickly eliminate an entire area before the plants have a chance to establish themselves. “Soybeans are extremely resilient but if they get cut off below that first leaf, the plant dies – there’s no coming back,” Macaulay said.
The key is getting the crop past its vulnerable early growth stages. “Protection for the first month to two months of that soybean’s life is really important,” he said. “Once they get big enough, they can essentially outgrow the deer pressure.”
Macaulay describes four primary approaches to managing deer damage: habitat management, repellents, fencing, and lethal control through hunting or crop-damage permits. But none of them are necessarily a stand-alone answer.
Fencing, for example, can be highly effective but expensive. But some farmers have installed eight-foot fences and recovered nearly the cost of the investment in just a few years through increased crop production, Macaulay says.
However, Macaulay is cautious about widespread fencing because of installation and maintenance costs, as well as potential impacts on wildlife movement and the broader landscape.
Repellents can provide another option, particularly when used to protect crops during vulnerable periods.
Habitat management is more complicated. Improving forest habitat by increasing sunlight to the forest floor can produce more forage and potentially reduce the incentive for deer to move into agricultural fields. But additional forage can also improve the habitat's ability to support deer, causing their numbers to grow. Without population control, those additional resources may ultimately sustain more deer and return pressure to crops.
“The habitat piece should be paired with hunting,” Macaulay said. Hunting and crop-damage permits can reduce deer density, although achieving a meaningful population reduction can require considerable effort.
For producers, the takeaway is not that there is one new technology or management practice that will eliminate deer damage. Instead, Macaulay's four-pillar approach encourages farmers to match multiple tools to the conditions on their farms — protecting young crops, managing deer numbers, considering the surrounding habitat, and using fencing or repellents where the economics make sense.
Preventing even a portion of avoidable yield loss can make a meaningful difference. For producers experiencing intensive deer damage and looking to implement solutions before the next growing season, read the full University of Maryland Extension publication, The 4 Pillars of Managing Deer Damage at https://extension.umd.edu/resource/4-pillars-managing-deer-damage-eb-2024-0740/.