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Abstract
Homeowners whose landscape plants are repeatedly browsed by white-tailed deer (Odocoileus virginianus) are interested in repellent products that are effective and long-lasting. New products come to market with limited experimental testing. We conducted a 10-week trial from Feb. through Apr. 1999 to test the duration and efficacy of six commercial deer repellents [Deer-Away Big Game Repellent (BGR) mix, BGR spray, Deer-Off, Deer Stopper II, Repellex, Tree Guard] and two experimental deer repellents (CU-A and CU-B) relative to each other and to untreated plants. Treated and control balled japanese yew (Taxus cuspidata) shrubs were placed at each of 10 homeowner sites with known white-tailed deer damage near Ithaca, NY. Yews are frequently eaten by deer during winter and provide a good bioassay for testing repellents, especially during the winter months. We checked shrubs once weekly and took photographs of damaged yews to measure the amount of deer browsing. We calculated the surface area of shrubs in each photograph by using digital analysis software. To determine significant differences over time, we applied statistical analysis using analysis of variance. Deer repellents that provided the most consistent protection were BGR spray, BGR mix, Deer-Off, and Deer Stopper II. The japanese pachysandra (Pachysandra terminalis) extracts in experimental repellents CU-A and CU-B were not effective. The performance of other commercial repellents varied considerably among sites, and these products were unreliable.
White-tailed deer populations and their impacts have continued to escalate in recent decades in suburban and natural areas (DeNicola et al., 2008). Deer damage to ornamental flowers and shrubs, crops, nurseries, and orchards is substantial throughout many areas of North America (Drake et al., 2005). Economic loss caused by deer damage to landscape plants has been estimated at $6.4 million to $9.5 million annually in Westchester County, NY, alone (Connelly et al., 1987). Nationwide, the economic impacts attributed to deer have been estimated at $100 million and $251 million annually for the agriculture and urban sectors, respectively (Conover, 1997). In southeastern New York, nursery producers with deer damage spent an average of $20,000 and homeowners spent an average of almost $500 for plant replacement costs in 1988 alone (Sayre and Decker, 1990).
Several non-lethal alternatives exist for managing deer damage, including fences, repellents, and...