Deer pose a persistent challenge to orchard management, impacting tree health and productivity. Deer frequently browse on new shoots, buds, and foliage, which is particularly destructive to young trees as it removes the growth needed for structural development. Browsing leaves a rough, torn appearance because deer lack upper incisors. Male deer also cause significant harm during the autumn rutting season by rubbing their antlers against the trunks. This antler rubbing can strip the bark completely around the trunk, an injury known as girdling, which often kills the tree by interrupting the flow of nutrients.
Utilizing Physical Barriers
Physical exclusion is the most effective method for protecting apple trees, especially in areas with high deer populations. The primary strategy is installing a perimeter fence tall enough to prevent jumping; for white-tailed deer, this means a minimum of eight feet. Common materials include woven wire or plastic mesh, and the fence should be kept close to the ground or buried to deter crawling underneath.
High-tensile electric fences are an alternative for large orchards, using high-voltage energizers to deliver a deterrent shock.
Individual Tree Protection
For individual trees, particularly young saplings, protection focuses on preventing browsing and antler rubbing. Individual wire cages made from heavy-gauge welded wire fencing are highly effective. These cages should be five to six feet tall to protect against browsing and wide enough that deer cannot reach the foliage. Trunk protectors or tree wraps, such as plastic mesh, can be placed around the base of the tree to guard against antler rubbing and chewing by smaller pests like rabbits and voles.
Applying Repellents and Sensory Deterrents
Repellents offer a non-physical method of protection by making trees unappealing through taste or smell. Products are categorized into taste-based (contact) and scent-based (area) formulations. Taste-based repellents are applied directly to the parts of the tree deer might eat and often contain active ingredients like putrescent egg solids or capsaicin.
Scent-based repellents rely on strong odors deer find unpleasant, such as bone tar oil or predator urine. These can be sprayed on the foliage or strategically placed on perimeter posts near the trees.
The effectiveness of any repellent depends on a consistent application strategy. Repellents must be reapplied frequently, especially on new growth, and after heavy rain, which washes away the product, necessitating reapplication every two to four weeks.
To prevent deer from becoming accustomed to a single product, it is beneficial to rotate between different repellent types or active ingredients. This rotation reduces the likelihood of habituation. Non-chemical sensory deterrents, such as motion-activated sprinklers, are available, but deer quickly acclimate to these scare tactics, limiting their use to short-term situations.
Orchard Management Practices to Reduce Attraction
Cultural practices within the orchard can significantly reduce its appeal to deer. Focus on the timely removal of dropped apples and fallen fruit debris from the orchard floor, as this concentrated food source attracts deer.
Strategic pruning and tree training are important tools for defense. Removing low-hanging branches and training the canopy above the deer’s reach lifts the primary feeding target out of the browsing zone, reducing the accessibility of buds and shoots.
Preventative action should be intensified during high-risk periods. This includes late fall when scarce natural food sources increase browsing pressure, and during the rutting season (late summer through autumn) when antler rubbing is most critical. Planting new trees away from known deer travel corridors also minimizes damage.