As we plan for Labor Day weekend, and do our back-to-school shopping, our thoughts are naturally turning to the approaching cool weather months. And for those of us involved in landscape health, our thoughts are turning to… deer.
As temperatures drop, and accessible food sources in forested areas become scarce, those graceful animals will increasingly visit residential properties to score some easy meals. White-tailed deer (the variety most prevalent in our SavATree customer areas) are herbivores. They prefer to eat grasses, flowering plants, herbs, leaves, clovers, fruits in season, and high-fat foods like acorns when available. But when the pickin’s get slim, they’ll eat just about anything to survive – including the buds of your ornamental trees and shrubs.
If you have not actually seen the deer on your property – they’re most active at dawn and dusk — there will be other clear signs that they have paid your yard a visit. Deer begin by browsing from the top of the plant downwards, eating the most preferred plants first. As such, you will see that vegetation is trimmed clean from the ground up to the deer height, approximately 3-6 feet above ground. Deer lack upper incisors, so rather than biting off vegetation cleanly, they jerk or tear the plant, leaving a ragged, shredded surface.
In early fall, bucks rub their antlers against the trunks of small trees (usually one to three inches in diameter) to remove the velvet that has been growing on the antlers throughout the summer; this rubbing intensifies during the rut, and again in late winter to help them shed their antlers. Rubbing will leave the tree trunks with visible vertical scrapes and shredded bark, exposing underlying wood. If the injury is only on one side of the tree, the tree can usually survive. But if the damage full encircles the tree, it will most likely die.
What You Can Do
The three main options for preventing or reducing deer browsing of prized ornamentals are: putting up fences or barriers; planting deer-resistant plants; and using repellents.
The most effective method for preventing deer damage is to keep them off your property entirely. A solid fence is more effective than one with pickets, because deer won’t jump over a fence when they can’t see what is on the other side. Deer are good jumpers, so fences should be at least eight feet high, and extend underground to prevent fawns from crawling underneath them. If fencing your entire property is either impractical or too expensive, you can erect local barriers. Individual trees can be protected by pounding tall vertical barrier stakes into the soil around each, a foot or so from the trunk. Individual shrubs and plants can be wrapped in deer netting or fenced off. Susceptible deer-attracting plants can be located near your home within a fenced area, with deer-resistant varieties planted on the outside of the fence.
Deer resistant plants
No plant is “deer proof” — many factors, including the season and the depth of their hunger, will affect what deer feed on. Generally, however, plants that are bitter, spicy, and thorny are extremely unpalatable to deer. Plants known to be resistant to deer browsing include pachysandra, daffodils, birches, Japanese andromeda, boxwood, spruces, oleander, rosemary, mountain laurel and autumn sage.
Conversely, the ornamental plants notoriously susceptible to deer damage include: hostas, azaleas, yews, arborvitae, apple trees, euonymus, rhododendrons, tulips, and hydrangea. And don’t try to fool the deer by mixing plants they like among those they dislike — they’ll simply trample the plants they dislike to get to those they prefer.
Rutgers University has created an extensive listing of deer-resistant plants, with corresponding codes indicating the degree of their resistance.
There are commercial products that deter deer by making plants taste or smell unpleasant, using such ingredients as inedible egg solids, cayenne pepper extract, and garlic. Contact repellents are directly applied to plants and repel deer by taste and odor. Area repellents are applied to the entire problem area of the yard and keep deer away due to their unpleasant odor. The key is to alternate the repellents used, otherwise deer become accustomed to the same repellent over time and begin to ignore it. Repellents work best when applied before feeding patterns develop, and when they are reapplied every month (especially after a rainfall).
Sound deterrents can also repel deer, since these animals have large ears and very sensitive hearing. Unexpected or unusual noises, even quite soft ones, can scare deer away. One popular approach uses ultrasonic devices that emit sounds at wavelengths animals can hear, but people can’t. Ultrasound tactics have an additional advantage: they will not keep your family or neighbors awake at night!
Integrated, Continually-Changing Tactics Get Best Results
No single tactic works on all deer, and all tactics need to be changed up from time to time to keep the deer from adapting. Contact your SavATree arborist to learn about our multi-pronged deer control program that combines our proprietary ultrasound units with deer repellent treatments. Field experience on thousands of properties in high deer pressure areas has shown our solution to be far more effective than deer fencing or repellent treatments alone.