DEER
(Adapted from 1992 Pest Management Recommendations for Commercial Tree-Fruit Production, Cornell Cooperative Extension, wildlife damage section by P.D. Curtis, M.J. Fargione, and M.E. Richmond.)
Deer browsing in orchards causes serious economic losses. Newly planted orchard should be protected by deer fence.
Many growers experiment with noncommercial deer repellents. These materials currently have no EPA registration, and their effectiveness is quite variable. To use small deodorant soap bars, drill a 1/4 inch hole through the center of the bar. Leave the wrapper attached because it reduces weathering, and if left in place bars may last several years. Attach the bars with string or wire to outer branches about 30 inches above the ground. There should be no more than 3 feet between bars within the tree. Caution is advised as bar soap sometimes increases vole damage. Some birds, such as crows, occasionally cause damage to new growth while feeding on soap bars. Human hair (from barber shops or styling salons) can be applied in 1/8 inch (or less) mesh bags and hung in mid-fall and early spring in the same distribution pattern as described for soap bars. Additional applications may be necessary in wet seasons. Light cloth bags filled with 1/2 to 1 cup animal waste can be used in the same way.
Several commercial repellents are available to reduce deer browsing in orchards. With repellents, some damage must be tolerated even if the browsing pressure is low. None of the existing repellents provide reliable protection when deer density is high. Repellents may be cost-effective when light to moderate damage is evident, small acreage is threatened, and if few applications will be needed for adequate control. If these three conditions are not satisfied, it is best to consider other alternatives.
If browsing pressure is severe, a long-term plan is needed. The plan should consider exclusion alternatives, habitat modifications, and reduction in animal numbers. Exclusion methods and habitat modification may require more initial effort and expense, but provide longer-term damage prevention.
Fencing is the most common exclusion technique. High-tensile woven-wire fencing provides the ultimate in protection and durability. Deer can be successfully excluded from large areas with an 8-10 foot woven-wire fence. Another advantage of this design is its relatively low maintenance requirement after construction. Disadvantages include the high initial cost, and the difficulty in repairing damaged sections.
A variety of multi-strand, high-tensile, vertical or sloped electric fence designs may effectively exclude wildlife. Electric high-tensile fences can be complete physical barriers, or more often, act as a psychological deterrent. Deer can be excluded with a 5-6 foot electric fence, even though they can easily jump over woven-wire fences of this height. If properly installed, high-tensile electric fences are easily repaired, and initial cost may be half as much as for 8-10 foot woven-wire designs. Disadvantages include the need for frequent monitoring of fence voltage and for vegetation control to maintain shocking power.
The most common reasons why electric fences fail to exclude deer are:
The use of a bi-polar fence charger, and setting an electrified bottom wire no higher than 10 inches above the soil, are two measures which help insure that probing deer are shocked. Under certain conditions, deer will violate these fences, requiring elimination or re-education of the problem deer.
For further information on preventing deer damage, contact Cooperative Extension for a copy of Controlling Deer Damage in New England Orchards by Lord, Calvert and Parkhurst. Cooperative Extension may also be able to provide information on fence suppliers.