 |
| FIGURE 96. Bird damage to winegrape clusters. |
|
| FIGURE 96. Bird damage to winegrape clusters. |
Crop damage in wine grape vineyards due to bird depredation appears to be more pronounced in recent years (Figure 96). This may be due in part to the increasing acreage of highly palatable wine grape cultivars being grown.
Several Midwest wine grape growers have found that birds are attracted to the early ripening varieties such as Marechal Foch, Leon Millot, Pinot gris, and Baco noir. There is commonly an increase in bird activity in vineyards as the berries near veraison. This is a critical time to persuade the birds to move elsewhere or try to prevent them from reaching the mature berries.
Birds that are commonly observed in Midwestern vineyards are European starling, American robin, Northern mockingbird, Northern oriole, and Common grackle. Other birds such as House finch, Cardinal, Cedar waxwing, Gray catbirds, and American goldfinch have also been observed in vineyards at various times. Migrating or local flocks of birds will begin testing grape berries at veraison.
Several types of management measures have been implemented in vineyards to deter birds from feeding, including bird netting; visual, sound, and chemical repellents; and birds of prey.
Growers have often tried to exclude birds from the grape canopy by draping bird netting over each individual trellis row (Figure 97). Netting is usually rolled out between the rows and pulled over each trellis and fastened together to prevent netting from blowing off. This provides a good barrier to feeding birds. Mechanical rollers to lay out and take up bird netting are available commercially. Netting must be in place by early veraison to assure that no fruit is damaged or lost.
 |
| FIGURE 97. Bird netting draped over grape canopy using a net applicator. |
Some of the most frequently used visual devices include scare-eye balloons, Mylar tape, tin pans, streamers, and other shiny and fluttering objects. The effectiveness of these visual deterrents has been limited. Birds are very capable of adjusting to new objects in a relatively short period of time. This type of deterrent should only be used in a limited time frame and, more appropriately, should be included in an integrated bird-management system.
Some growers have tried to set up nesting poles to encourage falcons and hawks to nest in vineyards. When large avian predators are active in the vineyard, fruit-eating birds will tend to stay away from the area. Locating artificial owls and other birds of prey in vineyards has not been effective.
Propane cannons have been randomly placed in vineyards and set to go off at designated time intervals. Alarm systems that imitate bird distress sounds can also be located in the vineyard and will sound on a preset time schedule. Some of the more sophisticated systems can produce distress calls from different bird species, alternating the sound and length of time of each. The loud or distress noise will generally induce a panic in the birds, and they take flight to avoid a perceived danger.
As with the sight deterrents, birds often become acclimated in time to new sounds introduced into the vineyard. These devices should be used selectively with other control measures. The devices should be moved around the vineyard to reduce bird familiarity and avoid annoying neighbors living near the vineyard. Growers have resorted to shooting a shotgun or pyrotechnic pistols to create noise to scare birds from vineyards.
This type of bird control requires the application of a chemical compound to grapes. Birds find fruit treated with a chemical agent to be distasteful. Different chemicals have been tested as repellents to reduce bird depredation in fruit crops.
Methyl anthranilate, a naturally occurring compound in Concord grapes, was found to reduce bird feeding, but a noticeable foxy flavor appeared in wine produced from Vinifera and French hybrid grapes treated with this chemical. Sucrose (disaccharide) has been used to reduce bird depredation in fruit crops. Research conducted at Cornell University showed that birds were less likely to consume blueberries sprayed with sucrose.
Wild turkeys are appearing with ever increasing numbers in vineyards. As more vineyards are planted, wild turkeys tend to move through these areas in flocks looking for food and shelter. Unless preventative measures are taken to restrict their entry into a vineyard, there is little that can be done to prevent them from decimating a grape crop.
Wild turkeys, unlike domestic turkeys, can take flight and are often seen roosting in surrounding trees and brush. As with other birds, turkeys do not like loud and/or distressing sounds.
Standard bird netting can be used, although turkeys are more powerful and may tear the netting trying to get the fruit. High fencing can be used to turn back the turkeys.
Propane cannons will have some effect for the short term, but turkeys, as with other fruit-eating birds, become accustomed to the sound and within a few days may pay little attention. Shotgun and pyrotechnic guns may provide some means of distraction to wild turkeys, so they are less likely to settle in the vineyard.
Deer, like other wildlife, pose a serious threat to Midwestern vineyards. Many times deer have been observed foraging on young succulent grapevine shoots in early spring and continuing this feeding behavior into early summer. Food sources are scarce during budbreak, and deer are naturally attracted to any green tissue that emerges. Several different kinds of approaches have been used to mitigate the damage that deer cause in vineyards.
Chemical repellents should be used with caution on fruit crops. Some repellents are not labeled for use on any food crop, and others can only be used during dormancy or when there is no fruit present. Be sure to read and follow label directions when considering the application of a repellent.
Materials—human hair, dog hair, and soap—that are commonly used to deter deer are used because they smell unnatural or have the smell of a predator. These materials can be used effectively to prevent deer from entering vineyards.
There is some interest in using coyote hair to create a negative environment for deer. Coyotes are the main predators of white-tail deer in Ohio, and it has been reported that deer do not like to come near feeding areas that have been baited with coyote hair. As with the bird populations, deer can acclimate very quickly, and they can become familiar with a new odor. However, deer appear to avoid the area baited with coyote hair for several weeks, even when the bait is removed, according to APHIS research scientists.
Deer can be startled by unfamiliar sounds, and they are less likely to stay in an area in which strange, unnatural sounds are emanating. Propane cannons and distress signals can be used to send deer to flight. Moving the noisemakers around the inside and outside of the vineyard can help to dissuade the deer from entering the vineyard and make the situation somewhat less familiar. This should keep the deer on edge and less interested in foraging on the tender vegetation of the vines.
Grow tubes and mesh vinyl screens can be quite effective in protecting young vines from foraging deer. The cost will vary depending on the number of tubes and screens you purchase. They can be easily placed around the plants to protect the newly emerging tissue. One problem is that these devices only protect plants when first established in the vineyard. The vines will quickly grow out of the tubes and mesh screen, and then deer are able to reach shoots growing out of the top.
Fencing is one of the best means of preventing deer from entering a vineyard (Figure 98). The expense for some owners can be cost prohibitive. Poly Tape electric fence, commonly used to keep horses and cattle in pasture, is being used to control deer from entering vineyards. Some producers are using this in place of standard single-strand electrical fence.
 |
| FIGURE 98. Deer exclusion from the vineyard using an eight-foot fence. |
It has been observed that deer will not enter pasture with this type of fence surrounding it. The Poly Tape (1–1/2-inches wide) works well at a height of 5 to 6 feet, with four to five strands from top to bottom. Generally, only the first through third strands from the ground are charged.
Peanut butter on aluminum foil placed on the electrical wire is used to bate the deer. T-Posts are used to fasten the tape in place within the fence row. With any electric fence, grass and weeds must be kept under control or the fence could short out. Weed whacker or burndown herbicides can be used to control vegetation (Figure 99).
 |
| FIGURE 99. Integrated wildlife management using netting (background) for birds and two-wire electric fence (foreground) for raccoons. |