Trees in suburban and rural landscapes face a constant threat from deer activity, which can cause significant damage. This damage stems from two distinct behaviors: browsing (deer eating tender foliage and twigs) and rubbing (male deer scraping antlers against the trunk). Understanding the difference between these two types of damage is the first step in selecting the correct protective strategy. Implementing targeted protection depends on recognizing these specific threats.
Diagnosing Deer Damage
Correctly identifying the nature of the damage is necessary because different behaviors require separate solutions. Browsing occurs when deer consume new growth, typically during winter and early spring when food is scarce. Browsing damage is identified by the ragged or torn appearance of foliage and twigs. Since deer lack upper incisors, they rip the plant material rather than cleanly cutting it. This damage usually affects branches less than one inch in diameter and is found up to six feet off the ground.
Buck rubbing is a territorial and reproductive behavior, not a feeding one, occurring primarily during the fall rut (late summer through early winter). Male deer rub their antlers against the trunk to remove velvet and mark territory with scent glands. The result is vertical scraping or shredding of the bark. This damage is typically concentrated on young trees (one to four inches in diameter) between one and four feet above the soil. Stripping the bark can completely girdle the tree, interrupting the vascular system and causing the tree’s death.
Exclusion Methods: Physical Barriers
Physical barriers offer the most reliable, long-term protection by physically preventing deer access to the tree. For trunk protection against rubbing, individual barriers like plastic spiral wraps, rigid mesh guards, and tree tubes should be installed. These guards shield the bark from antler contact. Light-colored plastic should be chosen to prevent the material from absorbing sunlight, which can cause heat damage to the trunk.
To protect young trees and seedlings from browsing, tall enclosures are necessary to deter deer from reaching the foliage. Tree tubes, typically four to five feet tall, enclose the entire seedling and promote vertical growth. This helps the tree quickly grow past the deer’s reach. For established trees or groups, temporary fencing or wire cages can be placed around the drip line during vulnerable seasons.
The most effective solution for property-wide browsing control is a permanent perimeter fence. Since deer are adept jumpers, a solid, vertical fence must be at least seven to eight feet high to be deer-proof, especially in open fields. Alternatives include invisible mesh fences or electric fences. These options still rely on height and a clear physical or psychological deterrent to be successful.
Behavior Modification: Repellents and Deterrents
Repellents and deterrents discourage deer through offensive taste, unpleasant smell, or sudden surprise, without relying on a permanent physical barrier. Taste-based repellents are applied directly to the foliage. They contain ingredients like capsaicin or putrescent egg solids, which make the treated plant unpalatable. Scent-based products often use sulfurous odors, such as rotten eggs or dried animal proteins, to mimic the smell of a predator or decaying matter. This creates a fear response that causes deer to avoid the area.
Motion-activated deterrents, such as sprinklers, emit a sudden burst of water when triggered by movement. These devices rely on the startling effect of the spray and noise to frighten deer away. While initially effective, deer may become accustomed to these scare tactics, reducing their long-term effectiveness. The primary drawback of all repellents is that they are temporary and only protect the specific parts of the plant they cover.
Seasonal Application and Maintenance
The timing of protection application is crucial for maximizing the effectiveness of both physical and chemical methods. To prevent buck rubbing, trunk guards must be installed before the fall rut begins (late August or early September). These protectors should be removed in early spring to prevent moisture and insect buildup that can damage the bark.
Protection against browsing should be continuous, but barriers or repellents are most important before winter, when food scarcity increases feeding pressure. Repellents require frequent maintenance to remain effective, needing reapplication every three to four weeks or immediately following significant rainfall. To combat deer habituation, rotate between different types of repellents, such as alternating between taste-based and scent-based products. This prevents deer from becoming familiar with any single deterrent.