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Wildlife Control David G. Wilson |
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While everyone likes to see wildlife occasionally, you don't want to see it as a regular visitor in your strawberry field. This paper will cover the most damaging animals, how to identify damage, and practices to minimize damage. The white tailed deer is the most wide-spread and problematic wildlife pest of plasticulture strawberries. Since the near elimination of the deer's natural predators and a decline in hunting, the deer population has exploded in many areas. Deer are browsers that are attracted to the tender growth of strawberries in both spring and fall. Browse damage can severely reduce fruit set. Deer are most often observed feeding at dusk, dawn or during moonlit nights. Telltale signs of deer include triangular shaped hoof prints, upper leaves that have been eaten off, and deer "pellets" which are brown to black and slightly larger than peas. Plants that have been browsed will have jagged leaf edges or stems, as deer have no upper teeth and must tear the plant parts. A variety of tactics can be used to minimize deer damage. One of the most practical tactics is to allow hunting wherever permitted and to encourage hunters to take does. Biologists in Maryland estimate that 35-40% of the does must be harvested annually to stabilize the population and even more must be taken to reduce it. Fencing is the most effective and also the most expensive control option. To physically exclude deer, an 8 foot high woven wire fence costing from $5-7 per linear foot (labor and materials) is necessary. For $1.50-2 per linear foot a 7 strand high tensile electric fence can be constructed. This fence provides a psychological barrier which, when properly maintained, will protect berries from moderate to high deer pressure. The least expensive fence is the single wire peanut butter fence. Peanut butter is spread on the fence or under foil flags folded over the wire. The smell entices deer to touch the fence which gives them a harmless, but memorable, shock. This fence is a psychological barrier only and will protect a field from low to moderate deer pressure when carefully maintained. Scare devices such as loud noises and scarecrows have been used with limited success for short periods of time. Unless changed periodically, deer can adapt to many of these things. A commercial company is now offering free-roaming dogs to nursery and fruit growers at a cost that averages $0.65 per linear foot for invisible fence to confine the dog and $300 per year for dog care. Dogs may only be practical where the strawberry field is part of a larger area as dogs confined only to a strawberry field would cause extensive damage to the plastic mulch. A variety of commercial and non-commercial repellents are available which include smell and taste deterrents. Commercial preparations include Hinder, Miller Hot Sauce, Thiram, and Deer Away which costs from $12 to several hundred dollars per acre for repeat applications. Repellents must be reapplied after each rain and some products are not suitable for edible crops. Non-commercial repellents include human hair, fragrant soap, and slaughter house tankage. The effectiveness of repellents is not consistent and depends on the area, deer pressure, and availability of alternative foods. Depending on the location, birds can be a problem pest of strawberries. In Maryland mocking birds and robins are often found feeding on early spring ripe fruit. Birds tend to select the ripest fruit and will peck holes but rarely consume the entire berry. A variety of frightening devices offer only limited effectiveness. Recorded distress calls can be purchased and played or gas cannons can be used. Visual scare devices including balloons, owl decoys, reflective mylar tape or flags, and black rubber hose (which is placed on the ground to resemble snakes) work to varying degrees of effectiveness. Raccoons are nocturnal animals known to enjoy strawberries from time to time. Look for raccoon tracks in the soil or on plastic mulch, as well as berries which have been eaten from the tips. Raccoons may also show a preference for sweeter berries as seen at the Castle Hayne Research farm where only the Gaviotta variety was eaten. The easiest control tactic is to exclude raccoons by adding an extra hot wire or two to your deer fence near the ground. To maintain a hot fence it is imperative that the fence be kept clear of grass and weeds. Where legal, hunting and trapping of raccoons will reduce the number and decrease crop damage. While foxes don't eat foliage or berries they sometimes play in strawberry fields and will punch holes in plastic mulch and pull up drip tape. Electric fence wires placed at 6", 12", and 18" above the ground are an effective fox repellent. Foxes can also be trapped or hunted where allowed by law. The lowly mouse can also cause the strawberry grower major problems by chewing trickle irrigation tubing. Plastic mulch and foliage provides an inviting home. Remove weeds and other debris around fields which may harbor mice. If mice become a problem a variety of commercial traps and baits are available. The best defenses against wildlife are to anticipate potential problems, carefully monitor your fields, and take appropriate actions when a problem is observed. For more information consult your County Extension Office, your local wildlife authority, or the following references. Print References Kays, J. 1997 Controlling Deer Damage in Maryland, Extension Bulletin 354, Available for $2 from Production and Distribution, University of Maryland, 6200 Sheridan Street, Riverdale, MD 20737 Hyngstrom, S.E., R.M. Timm, and G.E. Larson eds. 1994. Prevention and Control of Wildlife Damage. Nebraska Cooperative Extension. Available for $45 from Wildlife Damage Handbook, 202 Natural Resources Hall, University of Nebraska, P.O. Box 830819, Lincoln, NE 68583-0819 An Evaluation of Deer Management Options. Available from Whitetails Unlimited, Inc. 414-743-6777. Internet References www.ces.ncsu.edu/nreos/wild/wildlife/prevent.html Online version of Prevention and Control of Wildlife Damage listing animals found in North Carolina. www.aphis.usda.gov/ws/ USDA Animal & Plant Health Inspection Service Wildlife Service's home page. www.oznet.ksu.edu/___library/wldlf2/welcome.htm Kansas State wildlife homepage with numerous fact sheets. Be sure to type 3 underlines before library www.wvu.edu/~agexten/wildlife/index.htm West Virginia Extension Wildlife site with extensive information on deer. www.smallfruits.org/ The Southern Region Small Fruits Center. |
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