Many vineyards focus their pest control efforts on small common insects, but there are much larger animals that put grapevines in danger as well. Rodents, birds, deer and other larger mammals feed and trample on grapevines, putting production at risk and compromising the quality of wine grapes.
Types of Wildlife in Vineyards
Depending on what region of the country your vineyard is located, you may be faced with many different animals that love to wander into your grapevines. Some of the most common wildlife species that negatively impact vineyards are deer, rodents, birds and raccoons. Birds, in particular, are notorious for pecking through fruit and damaging it so that it cannot be used for winemaking.
“Many different avian species can damage vineyards, but the most aggressive ones are flocking birds like starlings and blackbirds,” said Cory Gellerstedt, Co-president of Nixalite of America. “Even one bird peck to a grape can leave detrimental pathogens that can alter the taste of the fruit.” Based in East Moline, Illinois, Nixalite specializes in pest bird and wildlife control products, including bird netting, bird spikes and deer fencing.
“In larger vineyards, the loss of crops due to bird damage could be as high as 10-30%, resulting in millions of dollars’ worth of lost revenue, and in smaller vineyards, that percentage could be much higher, sometimes resulting in a total loss,” said Vahe’Alaverdian, master falconer and founder of Falcon Force.
Even if wildlife pests don’t eat the fruit on your vines, they may tear through leaves or damage shoots so that they no longer support the plant.
However, not all types of animals are a nuisance. Both sheep and geese provide weed control, llamas can be used to clear debris from vineyard rows, and armadillos are known to eat harmful insects. Meanwhile, dogs, outdoor cats and even bobcats scare away rodents and other small pests and protect sheep from predators.
Chemical Control Methods for Wildlife
Various chemical methods are available today to assist vineyards in controlling wildlife. However, it is vital when using chemical repellants that they effectively deter wildlife without harming vines. Many vineyard operators also want to be as humane as possible in their wildlife control methods and limit their use of poisonous chemical compounds.
Brett Miller, Northwest Territory Sales Manager for the Wilsonville, Oregon-based Bird Control Group, told The Grapevine Magazine that chemical repellents come in two modalities: primary and secondary. Primary repellents are irritants that produce a foul odor or taste to encourage birds to try a different food source, while secondary repellents invoke a physiological response in the birds.
Chemicals repellants are sprayed either directly onto fruit or into the air around the vineyard; however, as a former vineyard manager and winemaker, Miller said to be careful when spraying any chemical directly onto the grapes. “Spraying anything on the fruit or in the vineyard will affect the resulting wine in some way. I would never spray something on the fruit that is a physical deterrent to birds because it could easily affect the quality of the wine, whether directly by an off-taste, or indirectly by inhibiting yeast fermentation.”
Jon Stone of Avian Enterprises in Sylvan Lake, Michigan, told The Grapevine Magazine that Avian Control Bird Repellent has proven to be the most effective chemical control method on the market for controlling birds in vineyards. The main reason for this, Stone said, besides it’s effectiveness, is that it does not change the taste or color of the wine.
“There have been no reports of unexpected changes in any wine made with grapes that have been treated with Avian Control,” said Stone. “The active and inert ingredients in Avian Control do not penetrate the skin of the fruit. Avian Control will not translocate into the treated crop. Translocation is the tendency of a compound to move through the tissues of a plant. This effect is particularly troubling when repellents translocate from the outer skin of the fruit through the skin and into the fruit body. When this occurs, a distinct change in taste can be noticed. Due to its unique formulation, Avian Control remains on the surface… and does not translocate into the plant or its fruit, preserving the natural taste of the crop. This is an important difference between Avian Control and other bird repellent products currently available.”
Stone said that Avian Control repels only birds and has no effect on humans or domestic animals. The active ingredient, methyl anthranilate, is widely used in foods designed for human consumption. The FDA has classified all of the ingredients in the Avian Control formula to be “Generally Regarded as Safe”.
The same cannot be said for rodent control. Allen Hurlburt of H&M Gopher Control in Tulelake, California, said that all chemical rodent controls, such as strychnine baits, aluminum phosphide (phostoxin), and anti-coagulants, are problematic because their effects are not limited to the targeted rodent.
“Phostoxin, especially, is very dangerous for the operator to handle,” Hurlburt said. “Regulations vary from state to state, but materials can be difficult to obtain and usually require permits from county agricultural departments.”
Natural Ways to Control Wildlife in Vineyards
Most modern wildlife control revolves around natural, organic and non-chemical ways to keep animals away from delicate grapevines. Odor repellants can be sprayed around vines or mounted on the trellis, sound repellants startle deer, and fences and barriers keep out larger pests.
Grow tubes and mesh vinyl screens are commonly used in vineyards for wildlife pest control, as well as bird netting to provide an effective barrier between avian pests and plants. Some vineyards allow hunting to control local deer populations. Meanwhile, some small vineyards experiment with natural remedies and alternatives to chemicals, such as egg-based sprays and garlic-based juices.
Netting and Barriers
Gellerstedt of Nixalite of America, Inc. told The Grapevine Magazine that his company offers a wide variety of bird and wildlife control products for vineyards, including bird netting, fencing, repellents, traps, sound and visual deterrents. He said that vineyard bird netting is very effective, although it is the most labor-intensive and costly.
“Our most popular net is constructed out of soft polyethylene knitted three-quarter-inch mesh,” Gellerstedt said. “The netting is simply draped over the vines to provide protection during the growing season and then removed just prior to harvest. With proper care, quality netting can be used for many seasons.”
For deer and wildlife fencing, Gellerstedt recommends installing a fence that is eight feet or taller to prevent animals from jumping over it.
Other solutions that Nixalite offers are acoustic devices, such as propane cannons and hailing devices for short-term and occasional use. Meanwhile, visual deterrents, such as scarecrows and reflective ribbons, are simple and affordable but usually only provide temporary results.
“I believe bird and wildlife exclusion with netting, barriers and fencing is the most effective technique, although it is not always feasible because of labor and cost,” Gellerstedt said. “Many successful bird and wildlife management programs use a combination of products and techniques to achieve effective results.”
Lasers can also be useful in deterring birds. Miller of Bird Control Group said that his company manufactures and sells a class 3B laser and that its automated AVIX Mark II laser is the most popular with vineyard managers.
“The laser is an expanded green beam that is seen as a physical object by the birds. With its constant movement, the birds don’t know how to categorize the beam, making the area look uninhabitable and pushing them elsewhere,” Miller said. “One of our automated lasers will cover 20 to 40 acres of vineyard, giving each vineyard 24-hour protection and reducing damage from birds by 70-95%.”
“Birds are inherently visual,” Miller said. “They have a very high eye-size to head-size ratio, and most use each eye independently. Their eyes are their main defensive and offensive mechanism, and Bird Control Group’s laser technology leverages their keen eyesight to give farmers the advantage.”
Miller told The Grapevine Magazine that as a vineyard manager, he found the best bird management solution to be Bird Control Group’s laser system used in conjunction with propane bird cannons and mylar tape. Cannons and tape alert birds, while the laser creates an environment that pushes them off the field.
Another way to intimidate and scare off nuisance birds is falconry-based bird abatement. Falcons and hawks are natural predators, and often their presence alone is enough to deter prey species. Falcon Force’s Alaverdian told The Grapevine Magazine how falconry-based bird abatement is quiet, discrete, organic, eco-friendly and sustainable.
“Our team of expert falconers releases one of our falcons upon the first sighting of birds in the morning, and the falcons pursue the prey with the intention of catching them. Nothing scares a prey species more than the fear of falling victim to a predators’ meal,” Alaverdian said. “However, it is not our intention to let the falcon catch the prey, so as the flocks of starlings disburse out of sight, the falconer calls the bird back in, and the falcon is rewarded for his pursuit. Each flight may last between ten minutes to an hour, depending on the time of day and temperatures. Once a bird is called in, a fresh falcon is prepared to patrol the next incoming flock. Each bird may be flown two to six times a day.”
“Falcon Force is the marriage of a very deep passion for the ancient art of falconry coupled with the practical use of raptors for bird abatement in a modern-day landscape,” Alaverdian said.
When it comes to rodents, Hurlburt of H&M Gopher Control said that non-chemical wildlife control methods like owl boxes have not proven to be very effective. However, he said that the Pressurized Exhaust Rodent Control system has proven to be very effective in reducing populations of burrowing rodents from 65-100% in the first treatment.
“University of California field trials, as well as farmer reports, have proven that the PERC system works very well in burrowing rodent control programs,” Hurlburt said. “Safety for the operator, bystanders and non-targeted animals has made the PERC system the first choice for burrowing rodent control.”
H&M Gopher Control’s most popular model for rodent control among vineyards under 100 acres is the company’s 206 unit. “Because vineyards can only treat one row at a time, multiple 206 units rather than the larger machines can be a more efficient use of capital and labor.”
When Wildlife Control is Most Important
The best time to start thinking about controlling wildlife is right after planting, and, based upon the local wildlife activity in the area, a plan for the whole season should be put in place. Different animal pests tend to strike at various times during the year. Closely monitoring vines throughout the growing season for signs of a wildlife presence or damage will help you form and adapt your pest control strategy accordingly.
Miller of Bird Control Group said that bird control efforts start at veraison, the point in berry ripening when the vine begins focusing on seed development and cell expansion rather than cell division.
“Veraison occurs 45 to 65 days after bloom, depending on climate and variety, when the sugar level is around 12º Brix,” Miller said. “Once the berries turn color, the birds will test the fruit, and like humans, they truly only like to eat the berries when there is optimal sugar.”
However, Miller also said that bird behavior is dependent on more than just the wine grape crop.
“Vineyard birds are eating summer bugs, other fruit crops and seed crops,” Miller said. “Wine grapes are often grown in very agriculturally-rich locations, so the birds are there to eat it all. Each vintage is different, and the longer the winemakers let their fruit hang, the more they will have to battle our avian friends.”
“Grape-growers who have the most success using Avian Control Bird Repellent start spraying their grapes directly before the scout birds are even in the area,” said Stone of Avian Enterprises. “If the grower can start spraying before the scout birds inform the rest of the flock of the buffet below, the grower has a very good chance of keeping most, if not all, the birds away from their grapes. This process always happens before veraison. Most growers will then continue to spray their grapes once per week at a rate of anywhere from 32 to 42 ounces until they harvest.”
Falcon Force is typically contracted to service a vineyard from veraison to harvest, with one of its team members and a fleet of four to eight falcons at the vineyard for eight to 12 hours a day. Depending on when the service starts, there may already be crop damage, which makes it harder to change bird feeding habits. Therefore, Alaverdian recommends starting falconry service while the fruit is still green and before nuisance birds establish a feeding routine, so his team can keep them away and the grapes safe.
“The one piece of advice I cannot over-stress is not to wait till the damage is well in progress and then call us,” said Alaverdian. “Our staff is limited, and we are often contracted months in advance, yet we are always willing to consult and offer flight demonstrations provided we have enough notice. We share an immense amount of information on our website and are always willing to share our experience and expertise with our wine-grape growing friends.”
Stone of Avian Enterprises agrees that bird repellency in vineyards requires early planning. “We tell our customers that the easiest and most effective way to keep their grapes free from birds is not to wait until there is a flock of birds attacking their grapes before they decide to start spraying Avian Control Bird Repellent. Prevention works!”
Unlike tiny insect pests, animals are more noticeable due to their physical presence and feces left behind. Yet, they can also be elusive and scamper away quickly or burrow underground, remaining undetected until significant damage is done.
“Gophers and field mice can be a major problem in vineyards. Gophers, especially, like grapevine roots and can severely damage new vineyards,” said Hurlburt of H&M Gopher Control. “Treatment is not a one-time operation. It needs to be on-going year-round to keep rodent populations below a financial crop-damaging situation.”
“The best time for rodent control is after the foliage has fallen and the operator has a better visual view of the ground in and around the vines. Gophers are active year-round through late fall, and winter treatment is optimum. Spring treatment after pruning works well, but it is also in the breeding season for gophers, so the females are not usually building new mounds when raising young.”
Developing Your Vineyard’s Wildlife Control Strategy
Gellerstedt of Nixalite stressed the need to be proactive and start early by putting a wildlife management plan in place.
“Protect the fruit before birds have an opportunity to destroy it,” Gellerstedt said. “Timing is critical when using netting, repellents and other deterrents. Sometimes it only takes a few days for a bird infestation to damage a crop.”
Miller of Bird Control Group advises vineyard managers to plan and take an integrated approach to wildlife control rather than waiting until it’s nearly harvest time, and birds are actively eating the fruit.
“Foraging birds are hard to move, and there isn’t a bird deterrent device in the world that can eradicate 100% of feeding birds once they have tasted the sweet taste of 20º Brix fruit,” Miller said. “Take the integrated approach and don’t rely on one tool. Just like the rest of your integrated pest management practices, you must use redundancies and the synergistic effects of multiple deterrents.”