Christine Harris, Eric Simonne, Joseph Eakes, and Keith Causey

There are an estimated 1.7 million deer in Alabama. The main strategies available to control deer feeding damage include physical barriers, scare tactics, extermination, and in some cases, shooting. Physical barriers are often expensive as well as unattractive additions to most residential and commercial landscapes. Scare tactics are only effective until the deer become accustomed to the tactic employed. Shooting is obviously an unacceptable alternative in populated suburban areas. One of the most selective and cost-effective approaches is chemical repellency.

To our knowledge, limited scientific data are available on the comparative efficacy of organic products. This study involved the testing of organic products containing garlic extract, fish oil, or putrescent whole egg solids as their active ingredients. The objectives of this research were to evaluate the continuous efficacy of selected organic products as deer feeding damage controls on horticultural crops and determine potential phytotoxicity.

METHODS
The study was conducted at the Auburn University deer pen facility. The enclosure is approximately 1 acre. Pine trees inside the enclosure provide adequate shade. Initially, 13 does and one buck were contained within the pen. Fawns were born mid-summer. No green vegetation was available to the deer other than that provided in the study. Water and deer feed were available to the deer ad libitum.

Three ornamental species were selected based on their importance to the landscape industry in the South and their perceived palatability to deer. ‘Francee’ hosta, ‘Rosa’ gomphrena, and ‘Pacifica Red’ vinca were grown off-site in trade-gallon pots following standard nursery practices in May and June 1998. Groups of nine uniform plants of each species were sprayed with selected products outside of the pen. All products were used as is and/or following the label’s recommendations (Table 1.) When required by the label, fresh product was mixed before each use.

Table 1. Characteristics and Application Rates of Selected Products
Treatment number	Product name	Source	Active ingredient and formulation	Comments
1	None			Negative control
2	Deer and rabbit repellent	Local retailer	Thiram	Ready-to-use spray; Positive control
3	Garlic + fish oil (1X)	GRL1	1+1 gallons in 98 gallons of water	Spray; some mixing required
4	Garlic + fish oil (2X)	GRL	1+1 gallons in 48 gallons of water	Spray; some mixing required
5	Garlic + fish oil (3X)	GRL	1+1 gallons in 30 gallons of water	Spray; some mixing required
6	Deer Away Powder	Woodstream2	Putrescent whole egg solids	Ready-to-use powder
7	Deer Away Kit	Woodstream	Putrescent egg	Prokit; regulated
8	Deer Away Spray	Woodstream	Putrescent egg	Ready-to-use spray; deregulated
9	Garlic (3X)	GRL	1 gallon in 30 gallons of water	Spray; some mixing required
10	Fish oil (3X)	GRL	1 gallon in 30 gallons of water	Spray; some mixing required
1 GRL: Garlic Research Labs, California. 2 Woodstream Corporation, Pennsylvania.

Feeding damage on each plant was rated daily for 6 days. Differences in growth habit among plant species resulted in different damage rating scales. The vinca and gomphrena made a single stem. The rating scale for these species was 0 - 3 where 0 = no damage, 1 = one-third plant cut off, 2 = two-thirds plant cut off, and 3 = plant cut at the pot line or uprooted. Hostas, however, make a rosette of leaves which vary in number from plant to plant. For hostas, the number of eaten leaves and remaining leaves were determined. All feeding damage data were transformed into percent destruction (0 = no damage; 100 = plant totally destroyed).

Products were ranked according to effectiveness for each batch. The ranks were added for each product to provide an overall rank sum index (ORSI). This allowed each product to be ranked for the entire study.

RESULTS
When the three plant species were treated and presented simultaneously to the deer, it became evident that the level of protection provided by the organic products used in this test depended on the plant species on which they were applied. Damage rating results suggest that under these conditions, the plant species is likely more important than the organic product sprayed. Based on the level of damage, hosta, gomphrena, and vinca were classified as having high, medium, and low palatability to deer, respectively.

Despite the fact that the efficacy of selected products was tested under extremely high deer pressure (14 deer per acre; no other source of live greenery available), differences were found among products. None of the products tested were phytotoxic over a 6-day period. In our observations, the smell of most of the products such as the garlic extract and fish oil did not carry over to the plants after spraying.

All products tested provided some level of protection against feeding damage incurred by white-tailed deer on the ornamental species (Table 2). Products containing putrescent whole egg solids were most effective in suppressing deer feeding. Treatments containing garlic and/or fish oil provided some protection, but were less effective than organic products containing egg solids. Among the garlic plus fish oil treatments, the 1x formulation provided less protection than the 2x and 3x formulations. Formulations of garlic and fish oil at 2x and 3x the recommended rate showed similar results.

Overall, the egg-based Deer Away Powder and Deer Away Spray were the most attractive products tested in this study due to their ready-to-use forms and effectiveness.