Deer Management

Damage from white-tailed deer (Odocoileus virginianus) is on the rise throughout the Northeast. As urban and suburban development encroaches upon rural areas where deer populations are high, deer look for food in landscapes, gardens, and nurseries. This artificial food source leads to population increase, regardless of the lack of space. To date, available deer control methods have not provided consistent results.

The best way to protect your plants is to first become familiar with the feeding habits of deer in your area. Deer may eat more than 500 different species of plants, but tend to be more selective. Deer will expand their foraging area when their preferred food becomes scarce. Deer may also develop a preferred taste for ornamentals. This usually occurs in late winter and early spring, when snow cover reduces the availability of their  natural foods and their fat reserves are depleted. Under these circumstances, deer will browse even the most resistant plants rather than starve. Since deer have small home ranges, they may become habituated and develop a preference for the fertilized gardens, flowers, shrubs, or trees on your property, rather than natural vegetation in the woods. Deer may also change their habits over time and may suddenly begin eating a plant that they avoided in the past.

Taking an Integrated Pest Management (IPM) approach is crucial in the battle  with deer. Nursery and home owners throw up their hands as control methods fail; however, these methods might have worked if used differently or integrated with other tactics.Each situation is different. What does not work at one site may be successful in another. The key is to follow some simple steps in analyzing each situation and develop a sound deer IPM control plan as follows:

1. Define Your Objectives: In choosing an appropriate strategy, it is necessary to identify individual expectations, limitations and thresholds. Answering the following questions will help pinpoint appropriate control methods: How much damage can be tolerated? How much can you afford to spend on controls? How much damage is there? What are shortterm and long-term goals? Be sure to weigh your options.

2. Analyze the Site: Deer damage may vary widely within a site. Document time of damage, intensity of damage, which plants are damaged, where the deer come from, and where in the nursery or landscape browsing is taking place. Sometimes problems can be solved by relocating preferred plants to one central location and using repellents, scare tactics, and/or physical barriers.

3. Develop a Plan: Plan to implement a full deer-control strategy in stages. IPM strategies include future planning and phasing-in of tactics. Consider your deer problem when choosing and locating future crops or landscape plantings.Budget for appropriate control strategies. Some situations may call for temporary controls, such as a scare tactic, until fencing or repellents are implemented.

4. IPM Decision Tools: As with other pest problems, an IPM approach is a key to success. Be aware that the nature of deer damage can change from season to season or year to year and is seldom identical in various locations.IPM, using several tactics in combination, offers flexibility and variety. Deer adapt and can overcome control methods. Thus, we have to be willing and able to change methods when necessary. It is also a good idea to alternate the use of repellents, when possible, in order to prevent deer from adapting to them. 

Network: Everyone with a deer problem will benefit from communication. Ask questions and share information about successful and unsuccessful approaches. Stay informed about new products and methods. Unnecessary damage can be avoided by timely and effective communication between professionals. Understand that herds, and even individual deer, differ in habits and patterns. A strategy that was not successful in one instance may well be the bestfor another.

URI Program

The URI Sustainable Landscape Program addresses the need for deer control strategies and works to develop an Integrated Pest Management approach. This approach includes the implementation of multiple control tactics. The table below lists some of the available methods for an IPM approach to deer control.

Repellents

Repellents are an effective way of controlling deer damage. However, it is important to understand how they work and when to use them. Repellents either taste bad or smell bad. The most effective products do both. With just a bad taste, the deer have to taste the plant to know that it is there. If a product only has a repellent odor component, the deer may feed anyway if they are hungry enough.

In areas of high deer density, repellents may be overcome by feeding pressure. To prevent this, it is important to use repellents on valuable and deer-preferred plants only, and then just before time of damage.

NOTE: Most repellents are not appropriate for food crops!

Following are some tips for using repellents:

• Read the label.

• Shake well before pouring into the sprayer and while applying.

• If the product is two parts stir each part well and then mix the two together.

• Use a strainer when pouring into the applicator.

• Apply at temperatures about 40o F. 

• Never store the product where it will heat or freeze (store at 40 – 90 o F).

• Do not apply when plants are wet and follow individual labels for drying time .

• Spray each plant thoroughly, just until runoff.

• Mix only what you need.

• Avoid allowing product to stand in backpack or hand sprayers.

• When possible, apply repellent before damage is expected to occur.

• To avoid resistance, rotate repellents and only use repellents during appropriate seasons and on appropriate plants. Repellents should be reapplied to new growth.

Suggested Commercial Repellents and Their Active Ingredients

By Nicole Lemieux and Dr. Brian Maynard, URI Department of Plant Sciences, 1999

Useful Website  RI Department of Environmental Management  http:// www.dem.ri.gov