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Vertebrate Pests

Deer: White-tailed deer can cause extensive damage to blueberries by browsing top-growth in winter. Deer can also cause damage to other small fruit crops. For more information on controlling deer, please see Deer Control in the Appendices.

Birds: Birds are a major pest problem in highbush blueberries. Left unchecked, they can destroy enough of the crop to ruin profitability of a planting. The loss of chemical deterrents has made bird control a more difficult task in recent times, but effective means are still available.

Management: Netting is the most effective way to keep birds out of the planting. Although initial costs can be high, most netting will last for many years if cared for properly. Netting should be hung over some sort of support structure built around the planting. Usually posts are set nine feet above the ground around the perimeter of the planting, and wire is run from pole to pole to form a grid over the planting. The netting is hung over this grid when fruit begins to turn color. Some temporary nine foot poles may be placed within the planting at intersections of the grid to keep netting from drooping. Bury edges of the netting or anchor it to the ground to keep birds from crawling underneath. Remove netting when harvest is complete, and store in a cool, dry place.

Visual scare devices have variable effectiveness on birds. Scarecrows, balloons, kites, snakes or stuffed owls may work on certain bird species in certain areas, but none seem to have widespread dependability. When using visual scare devices, place in planting only when fruit begins to ripen, and move regularly, at least once a day. Six scare-eye balloons per acre are recommended. Remove from field as soon as harvest is over to reduce birds becoming accustomed to the devices. Kites and helium-filled balloons of hawks positioned high above the planting have provided good results in some areas.

Noise deterrents, such as propane cannons, alarms and recorded distress calls seem to have the least effect on birds in blueberries, and may greatly annoy neighbors. A combination of noise and visuals may be effective, however. Several operations have hired people to regularly drive motorcycles and/or ATVs through plantings when fruit is ripe, and this seems to keep birds away quite well.

Bird Shield™, a repellent formulated from methyl anthranilate, is registered for use on blueberries, cherries, and grapes. Methyl anthranilate is commonly used as a grape flavoring in human food preparations. Bird avoidance is based on odor quality and irritation. To humans, this chemical has a grape-like or fruit odor and a slightly bitter, pungent taste. Unfortunately efficacy data does not support recommending the use of this material at this time.

Research using laser "scarecrows" is currently being conducted. Hopefully these devices will help deter birds in the near future.

Voles: Voles can be a serious problem in blueberry plantings. They feed on the bark of stems or on roots depending on which species of vole is present. In the Northeast, two species are found: the meadow vole (Microtus pennsylvanicus) and the pine vole (Microtus pinetorum). They may both be present in a blueberry planting. It is important to determine which species is present in order to make management decisions.

Size and appearance of the two species differ although it is somewhat rare to actually see them. The meadow vole has a long body (150-195 cm) and long tail, prominent eyes and ears, coarse fur, and is dull gray to chestnut in color with a gray belly. The pine vole has a short body (110-135 cm) and short tail, sunken eyes and ears, fine velvety fur, and is bright chestnut in color with a slate gray belly.

Evidence of their activity is more diagnostic. Meadow voles are active on the surface of the ground, feeding on the bark of the bushes and making shallow trails in the grass or mulch around the plants. Food caches and droppings can be found in these surface trails. Pine voles are active below ground, feeding on roots. Subsurface trails can be found by digging around the bushes. These trails come to the surface where mounds of dirt can be seen. Holes leading into these trails are about 1” in diameter.

Simply finding evidence of voles does not indicate a serious problem. To determine whether the voles are causing serious injury to the bushes, it is necessary to estimate the population of voles present. This requires some specialized sampling. It is best to contact your Extension Specialist for help with this sampling procedure.

Management: In some cases, removal of mulch material around bushes can help in reducing the meadow vole population. However, this is risky for bushes susceptible to drought stress. In those cases, choosing a mulch material that does not support tunneling (caves in easily), such as wood chips, is recommended. In some New England States, any application of toxicants or poisons for the purpose of killing any mammal or bird is prohibited. However, some toxicants may be allowed under certain situations with the proper permits. Call your Extension Specialist for recommendations.