By: Alyssa L. Ochs, Staff Writer
Animals of all sizes and types can have devastating impacts on grapes growing in a vineyard. There are direct economic impacts when animals eat, trample or otherwise damage grapes, which leads to yield losses and additional expenditures for pest control measures.
It is essential for vineyard owners to find a balance between the costs and labor involved in wildlife control and the benefits of a healthy harvest. We connected with leading vineyard wildlife control companies to learn more about the effects of wildlife and how to manage grapevine damage caused by wild animals.
How Wildlife Affects Vineyards
There are many ways in which animals can affect grapevines in a vineyard. For example, they can cause direct crop damage by eating grapes, especially when grapes mature right before harvest. Wildlife can contaminate grapes by leaving behind fungus and bacteria from their fecal matter. This residue often leads to off-flavors and bunch rot.
Vine damage occurs when animals gnaw on vines’ bark or dig around the base of plants, impacting current and future grape growth. There is also the possibility of soil erosion caused by wildlife trampling through the vines and damage to irrigation systems.
Some vineyards are faced with increasing costs for pest control because they need to address the damage already caused and then take more effective action to protect future crops. Changing weather conditions and increasing extreme weather events may also impact pests’ natural behaviors, requiring shifts in vineyard pest control strategies to accommodate new patterns of infestation.
Factors Affecting Wildlife Damage
A vineyard’s geographic location matters regarding wildlife damage to grapes. Some areas are more prone to animal activity, so it is important to understand the prevalence of wildlife populations and their feeding patterns where you are. You may experience more or less wildlife due to the availability of food and shelter, as well as your vineyard’s terrain and proximity to wild habitats and urban areas.
The type of wildlife present in your area also determines how much damage is likely to be caused, as some pests cause more harm than others. Fortunately, customized solutions are available to help vineyards improve their management practices and be proactive about minimizing wildlife activity.
Types of Damage Caused by Wildlife
Birds cause substantial damage by eating copious quantities of grapes, thereby reducing a vineyard’s yield. Starlings, sparrows, and blackbirds are problematic in many vineyards. You may notice pecking damage from birds on grapes, which leaves them susceptible to rot and disease.
Jon Stone from Avian Enterprises told The Grapevine Magazine, “While grapes that are consumed are a direct loss, pecked grapes may release juice, which can lead to bunch rot and even greater levels of loss. The juice can also attract drosophila flies and wasps, which can spread the rot to otherwise untouched bunches.”
Based in Sylvan Lake, Michigan, Avian Enterprises offers an EPA-registered solution to eradicate pest birds without causing harm to the birds, other animals, or humans.
Rodents are common in vineyards, including mice, rats, and voles. These animals are notorious for gnawing on vine roots and bark, which weakens or kills the vines. Rodents can contaminate grapes and vineyard equipment with their fecal droppings, creating risks for food safety and sanitation.
Deer are known for causing vine damage as they move through vine shoots, leaves and grapes. The movement of deer in vineyard rows reduces the plants’ ability to successfully photosynthesize and produce grapes. Because of their generous size, deer commonly damage vines and soil by trampling through the rows, causing root damage, soil compaction and trellis and fence damage.
George Horetsky, senior sales representative at Trident Enterprises, told The Grapevine Magazine that bucks also cause damage by rubbing their antlers on young vines, which can kill or weaken them. Based in Waynesboro, Pennsylvania, Trident Enterprises has been a wildlife exclusion expert for over 30 years and is a leading distributor of fence supplies.
In some areas, wild boars are a problem for vineyard owners. They eat grapes, leading to significant crop loss. Wild boars have rooting behaviors that uproot vines and damage irrigation systems. Predatory animals like coyotes and foxes can also disrupt vineyard operations and scare away beneficial wildlife and insects as they search for food.
Economic Impacts of Wildlife Damage
Horetsky from Trident Enterprises explained to us how wildlife damage, especially from deer, can lead to substantial economic losses for vineyards.
“Reduced yields from damaged vines directly impact revenue, while the cost of repairing physical damage and replacing plants adds to the expense,” he said. “In some regions, studies suggest wildlife damage can result in a five to 10 percent loss in total vineyard productivity annually. Beyond crop loss, vineyards may face increased operational costs for pest management and implementing preventative measures. Trident Fence’s wildlife control solutions are designed to help mitigate these losses by offering durable, long-lasting fencing options tailored to vineyard needs.”
Stone from Avian Enterprises shared with us, “The USDA has estimated that bird damage may result in a loss of up to an average of 40 percent of the crop. In a recently published article, Michigan State University states that losses can be as high as 95 percent and 60 percent in red and white varieties, respectively. Losses of over $100 per acre are possible. Clients who have used Avian Control® Bird Repellent have reported significant reduction in the level of loss, at times less than 10 percent.”
How to Prevent Wildlife in the Vineyard
According to Horetsky from Trident Enterprises, one of the best ways to control wildlife is to install effective fencing.
“High-quality fencing is the cornerstone of wildlife prevention,” Horetsky said. “Our fencing solutions, including poly and metal mesh options, are designed to withstand wildlife pressure, providing reliable protection for vines. Customizable features ensure the fencing fits the specific needs of the vineyard, whether it is a large-scale acreage or a boutique operation.”
Horetsky also recommended creating physical barriers to reinforce vulnerable areas like vineyard perimeters and entry points. He suggested pairing fencing with complementary measures like motion-activated sprinklers or repellents during peak wildlife activity. He also shared that inspecting fencing regularly is essential to identify and repair damage.
“By investing in durable, scalable fencing solutions and adopting best practices for wildlife deterrence, vineyards can focus on cultivating healthy vines and maximizing their yields, year after year,” Horetsky said.
Stone from Avian Enterprises explained that rather than trying to manage and repair damage already done, crop loss to foraging birds can be significantly reduced by taking a proactive approach to bird control.
“Frightening devices like cannons, distress calls and streamers have proven to be somewhat effective, while netting is effective but costly to use and very labor intensive,” Stone said. “Avian Control® Bird Repellent is a non-toxic liquid spray that, when used as directed, irritates birds, teaching the birds to avoid any treated areas.”
Stone said that Avian Control® has no effect on people, pets, or livestock. Also, it does not affect the taste of grapes and biodegrades rapidly.
“The key to successfully bird control is to begin applying Avian Control® Bird Repellent at the first signs of birds in the vineyard, usually around veraison,” Stone said. “Avian Control® can be used up to the day of harvest.”
Best Practices for Vineyard Wildlife Control
Stone at Avian Enterprises stressed that growers who have experienced the highest level of success with their company’s products have begun their applications early.
“Waiting to see how serious the damage will be allowed the birds to establish themselves in the vineyard, making it more difficult to repel them and ensuring ongoing damage until the birds leave,” Stone said. “Avian Control® works at it best when applied by itself. Tank mixing is discouraged, as the presence of other chemicals has been shown to reduce effectiveness, and a pH that is below 6.5 causes premature breakdown of the product. Properly applied, an application of Avian Control® can last up to two weeks.”
Meanwhile, Horetsky from Trident Enterprises provided several tips for effectively using his company’s wildlife control solutions in a vineyard. His advice can be broken down into the following: site assessment, proper installation, maintenance, complementary measures, and custom solutions.
“Conduct a thorough assessment of the vineyard to identify vulnerable areas, such as borders near forests or water sources,” Horetsky recommended. “Ensure fencing is installed at the correct height and depth. For deer, fencing should be at least 7.5 feet tall to prevent jumping.”
“Regularly inspect fences for damage or wear, especially after storms or during peak wildlife activity,” he continued. “Combine fencing with other deterrents like motion-activated sprinklers or repellents for a multi-layered approach. Finally, utilize fencing systems designed for vineyards, such as those with easy access points for equipment and workers, while maintaining robust protection.”
Vineyards can preserve their immediate productivity and long-term sustainability by incorporating these measures and investing wisely in wildlife control solutions with the help of trusted companies that understand the industry well.
“Wildlife pressure can be unpredictable, but proactive measures like high-quality fencing reduce risks and provide peace of mind,” Horetsky said. “Trident Fence is committed to helping vineyard owners find practical, cost-effective solutions tailored to their unique needs, ensuring their vines — and bottom lines — are protected season after season.”
