Mastering Pest Management

Nature takes a multi-pronged approach when attacking every inch of each vine you’ve planted. Before discussing how best to ward off and manage fungal diseases, insects, and wildlife, proficient farmers should approach starting the process of pest management with patience and understanding, two traits that cannot be undervalued in this hobby. 

Frustration, in any scenario, usually arises due to a lack of preparation or insufficient knowledge. The same is true in raising grapes. Most readers will remember planning their vineyard: How many posts, how many linear feet of wire, and the cost of each vine to name a few considerations. Pest control is the most difficult aspect to anticipate in terms of both time and money. The difficulty of farming is projecting the financial strain and the time it will take to deal with pests in the specific microclimate you’re working within. For example, you may have higher bird pressure or powdery mildew pressure than the nearest neighboring farm.

To budget for every possible issue in your area, start your studies by reading integrated pest management (IPM) handbooks. Talk to university extension agents, such as UC-Davis in California or Cornell University in New York. Take your research a step further and reach out to other local farmers. Ask to hear their wartime stories in exchange for a nice meal or a six-pack of beer (they already have enough wine). 

Once you have calculated the costs of materials you think you’ll need, it’s time to sit down with a calendar and identify the dates of events you foresee having to deal with. For example, if raccoons are an issue in mid-August, mark August 5 as the day to go out, buy the marshmallows, and set up the traps. If powdery mildew was an issue around July 4 in the past, rewind the whole season and plan an aggressive spray plan starting at budbreak. This may also include earlier fruit zone leaf removal. If you’ve pulled leaves away from the fruit zone in mid-June in prior years and still have powdery tissue on the fruit, mark your calendar for the first week of June instead. 

Fungal Control

Fungal pathogens offer the clearest illustration of proactive time management and budgeting. Anticipating costs for fungicides is a dizzying endeavor. Here are the questions that must be answered to create a comprehensive budget projection:

1. Which diseases affect my area?

2. What materials are available to use?

a. What are the application rates?

b. How will I rotate materials so I do not use the same ones back to back? 

c. How much does each container cost? Based on your answer, determine the cost per acre (or vine if you have a small planting). 

3. What is the cost of each application, including: 

a. Wear and tear on equipment, fuel, and water.

b. Personal protective equipment (PPE) that is required (found on the label of each pesticide).

c. The total time it takes from when you get into the tractor, start mixing, apply the application, clean the tractor, and drive back to the barn.

Before moving on to wildlife concerns, the time concerns involved in pest management are nebulous. As you read this article in the early spring, now is a perfect time to mentally prepare for the process. On your desk, you may have all the resources, projections, and figures necessary, but if you are caught off guard even once, half or all of your crop can irreparably degrade. One helpful tool I’ve used can be found through a resource company called VineSmith LLC. They make charts that you can hang in your pesticide shed that delineate and organize all of the above points. 

Weed wackers and other types of mowing and cultivating equipment used underneath the vine can be very dangerous as they encourage the spread of bacterial infections such as crown gall. Esca is another disease that affects the mature parts of the vine, particularly in older vineyards. To prevent the spread of Esca, clean and sterilize pruning equipment before traveling from one farm to another. If you have a management company or friends who help with the pruning in your vineyard, kindly request that they bleach their shears before beginning work on your vineyard. 

When considering viruses and bacterial issues, the importance of clean original planting materials cannot be overstated. Purchase your plants from reputable sources recommended by high-quality grape growers and university extension agents in your area. 

Controlling mold and mildew through spray applications is a cost that is nicely and neatly spread over the length of the season. This method of disease control does not usually require a large upfront cost. Yet some home growers with smaller plots may find that although they have a thorough spray program and are using the correct rates at the correct times, disease pressure remains frustratingly high. A trellis retrofit may be the final solution before ripping out the vines and replanting with more disease-resistant varieties. Many trellis systems can offer improved vine exposure to sun and airflow. A new trellis system (or a different grape variety) may also de-vigorate an over-vigorous vine. Vines with too much canopy will not only excessively shade the fruit (delaying ripening and producing off-flavors) but also shade itself, causing even more disease. Among other symptoms, canopy disease is evidenced by pale and yellowing leaves in the canopy’s interior. For this aspect of my consulting work, I am indebted to Richard Smart’s Sunlight into Wine textbook. It is a must-read for all grape growers. 

Insect Control

Insects, more so than fungi, are highly site-specific. For new growers, go through the following steps to familiarize yourself with invertebrate enemies in your area:

Pick up a copy of your local university extension’s publication for grape IPM.

Find a recommended identification guide with color photographs specific for your locality. For example, we grow grapes on Long Island, New York, and my favorite is Tom Murray’s Insects of New England and New York. 

Take a look at the sections on insect control and make a handwritten list of each insect mentioned. 

Refer to your guide and familiarize yourself with their appearance, habitat, where they would hide on the vine or trellis, and their life cycle. Life cycle is important because this will determine, among other things, when they reproduce and lay their eggs. This will then dictate when the most effective treatments can occur. Most university extensions have weather stations that measure GDD (growing degree days). Most insect species’ largest population numbers can be predicted by this measurement. For example, the European grape berry moth is difficult to see during its larval growth stage, when it likes to burrow into and through green, unripe berries shortly after bloom. 

It’s really important to distinguish your vineyard from your neighbors who may be close in proximity, but diverse in microclimate. When I started farming, I followed the GDD and found it accurate for some, but not all, of my farms. I worked with the same timing and application for three consecutive years to achieve a baseline “control” for this mini-experiment. I found that inland farms on the North Fork of Long Island have a warmer maritime climate that holds and regulates water in a very moderating way. Conversely, the vineyards I manage on the South Fork are only an hour’s drive away, but because they are closer to the ocean, their experience of the same weather pattern is delayed by a week. You must stay creative. You must experiment.

Now to address the least fun, but final part of this insect exercise. Take all your information and put it together on a spreadsheet. List your highest-threat insects along the right-hand column and mark down each insecticide with its rate and timing available for control. 

This may be one of the most vital points to adhere to: Beware of resistance warnings. There are many safe and effective insecticides that, if used too frequently, will cause species on your farm to become immune to their effects. Under no circumstances should you ever spray the same insecticide consecutively. This is largely true for fungicides as well. The only material I spray back-to-back is stylet oil early in the season when I’m spraying once a week. Both sulfur and stylet oil do not have any forward action so as a general rule I highly recommend either tank mixing something with protective capabilities or at least rotating with another material for powdery control — especially a week before and after bloom. After bloom, I stop using stylet oil. I’ve found that it delays ripening as compounded use of stylet oil can clog the stomata and other “breathing” apparatuses of the vine. 

When considering insect species, it’s imperative to account for the pests that spread grapevine viruses because they cannot be eradicated or controlled with fungicides. The grapevine mealybug is of primary concern as it transmits leafroll virus, which is gravely detrimental to the quality and quantity of the crop. Mealybug control illustrates the need for a farmer’s flexibility as they’re pests that require treatment in different areas of the vine and at unexpected times of the season. 

Animal Control

Insects and fungi have a slow, steady, long-game approach to destruction. Vertebrates play a different game. Never will you feel more at war than when defending against birds, raccoons, possums, rodents, groundhogs, gophers, moles, voles, coyotes, deer, turkeys, and other wildlife that looks at your grapes and sees an appealing meal. But don’t be overwhelmed. There is a solution for all. 

Let’s talk about birds first. Netting is the most obvious solution of which there are two different types. “Extruded,” meaning over-the-row netting, is thin, lightweight, UV stable, and black webbing with large 1 x 1-inch (2.5 x 2.5-cm) squares. Standard VSP (vertically shoot positioned) trellises are at a height of 6 feet (1.8 m) with an additional half foot (15 cm) of shoots and leaves above the top of the trellis. I recommend a netting width of 17 feet (5.2 m). This is most commonly applied with the assistance of a tractor as it can be difficult to apply by hand, though not impossible. 

We have one small vineyard of a quarter acre that has aromatic grape varieties and is surrounded by trees. Every year, we apply side panel netting as well as over-the-row netting because bird pressure is particularly high in this location. Side panel netting, which is a much tighter weave than over-the-row netting, is sometimes referred to as bee netting because it will prevent larger insects from entering. When not in use, it can be rolled up nicely onto the irrigation wire a foot or two off the ground. 

No matter what netting you purchase, do not buy white because it makes it nearly impossible to see what’s behind the netting. Do not underestimate flash scare tape, air cannons, and distress calls. As a rule, never count on only one form of defense against any critter. This rule can be applied to how you seal up your nets, too. For example, don’t exclusively use Zip Ties. Use staples, red catch wire clips, and anything else you can find to seal gaps in the netting effectively and efficiently. Netting is another subject that is best discussed with local farmers to understand what’s most effective in your area.

The most devastating pest is the broad category of “rodents.” If it has thumbs, you will need to be very proactive. In the Northeast, a single family of raccoons can eat hundreds of pounds (100+ kg) in a single event. On the West Coast, ground squirrels can eat an entire plot right before a crop ripens. Think of them as connoisseurs of ripeness: They will bypass the least ripe clusters on the row for the sweetest. Not only will you lose quantity when rodents attack your plot, but the average Brix will decrease to boot. Therefore, trapping and extermination are the first line of defense. Check with local municipalities to see if this is legal for the species you need to eliminate and keep in mind that the process can be time-consuming and costly, especially if you hire a professional trapper. If the pressure is light and you have a larger farm, I recommend Duke live cage traps. They are the most durable with a smart design to prevent breakouts. 

Even if you have a small population of deer in your area, don’t skimp on deer fencing. The right materials and application are key as deer pose a serious threat. Choose deer fencing that is the appropriate height of 10 feet (3 m) and apply solid pressure-treated posts with corners properly braced. Black locust tree trunks are commonly used as they’re more affordable than pressure-treated yellow pine, but they don’t hold up as well and will cost you money and aesthetic value in the long run.

The ultimate defense against anything on the ground is an electric fence. Electric fences for large and small rodent exclusion are not dangerous to humans and do not kill the target pests. Think of an electric fence as a training mechanism that teaches rodents to stay out. In comparison to deer fencing, electric fences are a fairly nominal one-time upfront cost. With an electric fence, you can install a permanent structure that will be a relief to have, particularly if you’ve ever used trapping as a preventative measure. If you already have a deer fence installed, there are simple methods for mounting electric wires around the gates. 

Growing grapes is a lot of work, and keeping those grapes hanging healthy on the vines until harvest requires both preparation and vigilance. But you can do it, and the reward at the end makes it all worth it.