Effect of Systemic Deer Repellent Tablets and Liquid on Deer Browsing of Containerized Ornamentals

Abstract

Economic and aesthetic losses from deer browsing of ornamental plants in nurseries and landscapes has increased significantly during recent years. This, according to wildlife specialists, is primarily due to hunting restrictions in urban areas. There are numerous so-called “deer repellents” on the market, but most are foliar applied and can be washed off or diluted with rain or irrigation. This study evaluated the effect of a systemically absorbed deer repellent tablet, Repellex (trademarked product), on deer browsing of containerized ornamental plants. A foliar applied counterpart, Repellex liquid, was also evaluated. The 1.5-gm tablets are a 14–2–2 fertilizer containing denatonium benzoate, lactose, ammonium phosphate, hydrous magnesium, and potassium sulfide. Two to eight tablets, depending on the size of the container, are placed adjacent to the root ball of the plant and 2 inches below the media surface at time of transplant. Gumpo azalea, Indian hawthorne, daylily, and Manhattan Euonymus were used for the study. Plants treated with tablets were held 6 to 8 weeks, according to manufacturer recommendations, under nursery conditions, then transported to deer-holding pens at the Whitehall Forest Research Station at the Univ. of Georgia. The pens, 1/2- to 1 acre in size, contained seven to 12 deer, depending on the study. Growth measurements initially and at weekly intervals were used to assess the degree of deer browsing. Results varied by plant species. Generally, the tablets were ineffective in preventing deer browsing when compared to the control. The foliar applied liquid was effective in reducing deer for up to 6 weeks when compared to the control. Plants treated with a tablet at time of propagation and two additional tablets when transplanted were browsed to the container within 2 days of deer exposure.