Dealing With Herbicide Drift By John Peragine Nature can be unforgiving to farmers. Honest people trying in earnest to make a living growing crops regularly face storms, drought, hail and many other types of natural disasters. Today, unfortunately, these people’s neighbors sometimes add to the problem by introducing one more difficulty: herbicide drift. All farmers face pressure from weeds. These pesky plants can consume resources — sunlight, water and nutrients — necessary for optimum plant growth. There are three primary ways to deal with the dilemma: pull, cut or use some other physical mechanism to kill the weeds; ignore them and take a loss of production; or use a substance to kill them. Hand weeding is not typically cost-effective beyond a small acreage farm, forcing larger farms to either accept a decrease in yield or use a chemical to kill the plants. Some herbicides have little negative impact on the environment or the plants they are sprayed on. Unfortunately, though, most large-scale crops are sprayed with volatile chemicals. Damage to grape vines caused by 2,4-D drift. Photos by Michael L. White, ISU Extension & Outreach Viticulture Specialist Agricultural technology over the past century has allowed farmers to deal with weeds in a very direct and definitive manner with the use of chemical herbicides. A common herbicide is the phenoxy type (2,4-D and dicamba). This is sprayed over crops like corn around the periphery of fields and is quite effective in killing broad-leaf weeds; it is equally effective in killing similar plants such as grape vines, and dicamba is currently the topic of much discussion through-out the Midwest and beyond where it has been linked to non-target crop plant damage. The Environmental Protection Agency defines drift as “The physical movement of pesticide droplets or particles through the air at the time of pesticide application or soon thereafter from the target site to any non- or off-target site. Spray drift shall not include movement of pesticides to non-or off-target sites caused by erosion, migration, volatility, or windblown soil particles that occurs after application or application of fumigants unless specifically addressed on the product label with respect to drift control requirements.” There are two types of pesticide/ herbicide drift: particle and vapor. Particle drift occurs when small droplets of pesticides or herbicides travel via the wind from the field they were being applied to onto other crops. Vapor drift occurs when temperatures in the upper 80s and 90s cause already-applied pesticides/herbicides to volatize into a vapor. These vapors then drift over great distances and destroy crops that are not immune to its destructive compounds. The good news is that many states have laws to protect farmers from the damages caused by herbicide drift. In Iowa, laws were enacted around grape-producing regions in the western part of the state to stop the use of highly volatile herbicides in the late 1970s. The damage was done, though, and it took almost 30 years for the grape industry to bounce back. Spray drift causes a reduction in yield, poor fruit quality and even grapevine death. Problems can continue years after the drift exposure, reducing the life of a vineyard. The degree to which crops are damaged from drift depends on the level of the susceptibility of the crop, its growth stage, environmental conditions, herbicide formulation, droplet size and the spray height above the target. Emotions Run High Because livelihoods are on the line, frustration and anger over herbicide drift often arises, and conflicts can ensue. Neighbors, farmers and companies will often apologize and promise they will not allow drift to occur again, but this is not always honored. Included on page 34 is a sample letter template that can be used to attempt to start a more positive conversation about drift. If your neighbor does not respond in a positive way, you could seek assistance from your state department of agriculture. Sample Letter ABC Farm 123 Any Street Anywhere, USA Date XYZ Neighbor 124 Any Street Anywhere, USA Re: Herbicide drift concerns Dear Neighbor, I hope this finds you well and that you are having a good growing season. I am writing to remind you that we have grape vines on two sides of the Old Grain Mill field in Hamlet township. We have registered on Driftwatch, which has a good map that shows where the vines are in case you have any questions. Here’s a link if you would like to see the online map: ia.driftwatch.org/map. I’ve also included a map that shows the location of the vineyards. Grape vines are especially sensitive to glyphosate, dicamba and 2,4-D. We have appreciated the care you have taken over the years to avoid any problems. Unfortunately, we have had friends in the grape community who’ve had severe damage, so it seemed like a good idea to bring this up again. Thanks for your attention to this. We’ve also spoken with your landlord about our concerns. If you have any questions, don’t hesitate to call. Yours truly, Friendly Farmer Organic Solutions There are a number of organic herbicides on the market, but they should be given the same attention as their synthetic counterparts. Organic herbicides do not offer a residual effect, which means they break down quickly after their application. This is good in that it reduces toxicity, but it also means that they have to be used more often. Organic herbicides are not selective and can kill basil as easily as a weed, so application should be done carefully. They should be applied directly onto weeds on warm, sunny, non-windy days. They often contain fatty acids, vinegar or acetic acid, or essential oils like citrus, eugenol or clove. Corn gluten meal can be used on larger farms, as it is a natural pre-emergence weed control for broad-leaf and grass weeds. Compensation Sometimes the damage due to drift is so severe that compensation is necessary to replace lost crops. Michael White, Iowa State University Extension & Outreach Viticulture Specialist, says that over 95 percent of drift damage cases are settled out of court. White suggests waiting before accepting payments from an insurance company. Some damage does not become evident until after the winter. Even though insurance companies do not like to carry claims over into another year, it is best to try to delay and not settle too soon. Once damage is suspected, White recommends taking pictures of healthy plants and damaged plants every week or two to demonstrate the progression of the damage. Resources FieldWatch/DriftWatch sensitive crop registry Northern Grapes Project Vineyard Herbicide Drift webinar, 3 November 2012 Factors Affecting Pesticide Drift. ISU Extension Options for Dealing with a Pesticide Drift Incident. Purdue Extension Reducing 2,4-D and Dicamba Drift Risk to Fruits, Vegetables and Landscape Plants. Ohio State Extension, January 2016 Using Buffers to Reduce Pesticide Drift & Wind Erosion. Pesticide Stewardship Org Preventing Herbicide Drift and Injury to Grapes. Oregon State Extension Avoiding Injury to Grapes from Off-Target Herbicide Exposure. University of Maryland Extension: Protecting Pesticide Sensitive Crops. University of Nebraska Extension: Herbicide Injury Diagnostic Key. University of Wisconsin Extension Air Temperature Inversions: Causes, Characteristics and Potential Effects of Pesticide Spray Drift Why Drift, Why Now, PPT dicamba/2,4-D vineyard drift ppt. Dr. Doug Doohan, Ohio State University, 11 May 2017 Editor’s Note: This article appeared in the March 2019 issue of Acres U.S.A. magazine.