Deer are adaptable generalist herbivores whose diet often brings them into conflict with fruit growers. For owners of Prunus species, such as plum trees, a common concern is the vulnerability of their orchard to browsing animals. Deer pressure can turn a promising harvest into a significant loss, especially where natural food sources are limited. Understanding this threat is the first step toward effective protection of these valuable fruit trees.
Plum Trees in the Deer Diet
Plum trees are definitively eaten by deer, serving as a recognized food source for white-tailed deer and other herbivores. Plum species, particularly the American plum (Prunus americana), have a highly digestible forage value, making them an attractive browse option. Deer consume multiple parts of the tree throughout the year, though damage severity fluctuates seasonally.
Deer especially target tender, nutrient-rich new growth, including young shoots, foliage, and developing flower buds. This browsing can severely stunt the tree’s growth and reduce fruit production in the current and subsequent years. The ripe fruit is also highly sought after, providing deer with a valuable source of carbohydrates and energy in the late summer and early fall.
Plum trees are moderately palatable, meaning they are preferred over less desirable plants but may not be the first choice when staple crops are abundant. This palatability shifts dramatically during environmental stress, such as winter or drought, when preferred forbs or grasses become scarce. In these lean times, deer rely heavily on woody browse, and plum trees can sustain devastating feeding pressure. Damage is often most significant on young saplings, where repeated browsing prevents them from reaching maturity.
Identifying Deer Damage Versus Other Garden Pests
Accurately determining the source of damage is necessary before implementing any protective measures. Deer browsing leaves a distinct, ragged appearance on branches and stems, resulting from the animal pulling and tearing vegetation. Unlike rabbits or rodents, deer lack upper incisors and must pinch and rip plant material, creating an uneven and splintered end.
This type of browsing typically occurs at a height between one and six feet above the ground, often creating a noticeable browse line on the tree. Damage from smaller pests like rabbits, conversely, is characterized by clean, angled cuts on the stems, appearing as though they were clipped with shears. Rabbits and mice also tend to cause damage close to the soil line, often girdling the tree by gnawing the bark completely around the trunk, especially during winter.
Another unique sign of deer activity is bark rubbing, which is not feeding but a behavior related to antler development. Male deer, particularly in the fall, will rub their antlers against the trunk or larger branches to remove velvet or mark their territory. This rubbing strips the bark off in vertical patches, often exposing the inner wood and causing significant structural damage to young trees with trunks larger than a few inches in diameter.
Physical Barriers and Exclusion Techniques
Physical exclusion is the most reliable and long-term strategy for protecting plum trees from deer damage. The most effective method is installing a perimeter fence that completely blocks access to the orchard or yard. The minimum height requirement for a permanent, deer-proof fence is consistently cited as eight feet.
This height is necessary because a deer can easily clear a lower barrier. Fencing materials should be sturdy and durable, with woven wire or heavy-gauge metal mesh being popular choices for their longevity and strength. The fence should also be secured at the ground level, or buried slightly, to prevent deer from pushing or crawling underneath.
For individual plum trees, especially young saplings that are most vulnerable, protective cages or wraps are a practical alternative to full perimeter fencing. These tree shelters should be constructed from rigid wire mesh or a similar material and must be tall enough to extend beyond the deer’s maximum reach, which is typically six feet. Cages should also be wide enough to prevent deer from pressing the mesh against the growing foliage to browse the leaves. Regular inspection of these physical barriers is necessary to ensure they remain intact and properly secured against determined deer.
Repellents and Cultural Practices
When a permanent eight-foot fence is not feasible, repellents and cultural practices serve as a secondary line of defense for plum trees. Repellents generally fall into two categories: taste-based and scent-based. Scent-based products, which often contain ingredients like putrescent egg solids or predator urine, work by triggering the deer’s natural aversion to foul smells.
Taste-based repellents, such as those containing capsaicin or Thiram, are applied directly to the plant material, making the foliage unpalatable after the deer takes the first bite. These deterrents must be applied consistently to maintain effectiveness, especially to new growth. Reapplication is required every two to four weeks, and immediately after significant rainfall, which can wash away the protective compounds.
Horticultural practices can also help reduce the risk of damage. Pruning the plum tree’s lower branches to a height of six to seven feet encourages the canopy to grow above the deer’s comfortable browse line. While this does not protect the fruit, it helps the tree establish a healthy, unbrowsed structure. Companion planting, which involves surrounding the plum tree with strong-smelling, unpalatable plants, can help mask the plum tree’s scent and make the area less inviting to deer.