The drift dilemma
Raemelton Farm in Frederick County, Maryland, experienced significant drift damage from a nearby property in 2017.
Hannah Mathers

The drift dilemma

Features - Nursery Production

Herbicide drift is likely to occur at any time. Know the proper proactive and reactive steps to take when it happens to you.

May 18, 2021

Photos provided by Hannah Mathers

Classic symptoms of dicamba injury on the Cercis canadensis showing the darker green color, puckered appearance, marginal chlorosis, and cupping with the upper leaf surface composing the outside of the cup. Plant foliage tested positive for dicamba, group 4 MoA.

You’ve tasked crews to scout for pests and diseases. But are you monitoring your crops for another potential problem – one that may be perpetrated by your neighbor? The predicament in question is herbicide drift, and pundits say it’s not a question of if you’ll experience drift, but when.

A common source of herbicide drift damage to nursery crops comes from two chemicals commonly used in ag, Dicamba and 2,4-D.

Drift can occur as particle drift or vapor drift, according to Tanner Delvalle at Penn State Extension. Particle drift occurs when small spray droplets move long distances due to wind. When a pesticide volatilizes or evaporates into the atmosphere and moves off site and damages non-target plants, it’s known as vapor drift. It’s important to know that drift, especially vapor drift, may travel more than 1 mile.

Row crops are not the only source of drift. For example, if your nursery is close to a golf course, a park, a maintained road, a rail line, or a residential development, it’s likely you’ll experience drift injury.

Steve Black, founder of Raemelton Farm in Frederick County, Maryland, experienced significant drift damage from a nearby property in 2017. It was early spring at his B&B nursery and trees were just starting to leaf out, the crew had stopped digging and was transitioning into planting and monitoring for pests. At first, Black and his crew noticed some oaks that “just didn’t look right,” he says. A local extension researcher visited the nursery and thought it could have been from a late frost. But these trees broke bud after the area’s last frost, Black recalls. Next, another extension professional observed the trees and thought it looked like herbicide damage, consequently asking Black what his crew sprayed. But that particular row hadn’t been treated with any herbicides since the previous summer. Then Black and his scouting crew noticed other trees that looked odd, such as red maples with “droopy” leaves and conifers with that same droopy characteristic, but in the leaders. Soon it became apparent that for some species of trees, the odd growth patterns were happening across the entire property. But for others, it appeared only at one end of the farm, what Black called a “spatial gradiation.” For the oaks, there was damage of some sort on every single specimen on the property. The trees closest to the drift source were in their second year of production.

Different species of trees have different levels of sensitivity. The dogwoods closest to the drift source had obvious damage, but that obvious signs dropped off the farther away from the source.

“And there is no remedy for systemic herbicide exposure except to water the trees and try to keep them healthy otherwise,” Black says.

After a handful of experts, including extension agents, university researchers and a for-hire scout, concluded it looked like herbicide damage, Black informed the Maryland Department of Agriculture (MDA), which sent a representative to take samples and begin an investigation. MDA acquired the spray records from everyone in the area (including Black’s own records), and they identified a nearby property that used Dicamba. Unfortunately, the operator’s spray records were not complete, to say the least. The investigation found that the farmer used concentrations and spray tips were specifically prohibited by the label.

Black contacted the farmer and explained the damage to his trees, and the farmer said he needed some time to think about the issue. Next, Black received a letter from the farmer’s lawyer who said to take it up with the farmer’s insurance company.

The insurance company was ready to settle, but the amount covered only about 10% of the damages.

“In my situation, the sprayer’s insurance policy considers herbicide drift as farm pollution and their policy was capped at a very small number,” Black explains. “So, the insurance company offers me this very small number and says once I accept it, I have to agree not to pursue any more damages. They put me in the position of either taking the settlement, which is not enough to cover the losses, or take legal action. I can’t think of anything worse than suing your neighbor. It’s so far afield from who I am as a person and how I was raised.”

Mottled and misshapen leaves caused by dicamba drift on Koelreuteria paniculata 'Golden Candle'. Foliage tested positive for dicamba.

Data collection

As soon as Black noticed the damage, he documented every detail in hand-written notes and photos.

“At moment one when you suspect a drift event, you open notes and start a diary with dates, times and specific observations,” Black says. “Everything you do, every person you talk to, that information goes in the diary.”

Although your state ag official will collect samples, Black says to hire a third party to collect foliar and soil samples for testing, including areas where damage looks its worst, where it’s not as obvious and from asymptomatic areas.

And take photos of everything, he advises.

“I was out with the camera and a ruler, and I'm holding branches up to the ruler to monitor the growth patterns and the lack of growth. I documented the leaves that first came out – the ones that were so damaged,” Black says. “And then I documented the leaves as they became twisty and tiny. As the growth progressed over the summer, the leaves got closer and closer to looking ‘normal’ normal again. I had indicative photos of every single species on the farm. And because I used my cell phone, those photos were geo-referenced and dated. It became this monstrously, huge collection of photos, but ones that I needed to help assess the damage. All the data I collected were contemporaneous notes, which beat the ‘he said vs. I said’ arguments.”

Plus, Black keeps inventory and growth records for each tree, so he knew how much every Quercus sp. grows each year, for instance.

Black hired Hannah Mathers, owner of Mathers Environmental Science Services in Ohio, to survey the trees and provide confirmation that his crops were damaged by herbicide drift. Mathers has been conducting studies on herbicide drift and nursery crops because of the lack of published information on the topic.

Analyte tests are critical when it comes to a drift event, Mathers says.

“In my work, I’m trying to correlate the ppm you get from the analyte test with the injury I’m seeing,” she adds. “And certain growth stages are more affected than others, and certain cultivars are more affected than others. That’s why the analyte tests are so important.”

And the sooner tests are conducted, the better your data will be.

“If it’s been six months from the drift event and we get a result of .2 ppm of a chemical, that’s not reflective of what actually happened,” she says.

In her research, Mathers has observed twisted leaves with Group 2 herbicide drift. When Group 4 herbicides drift on to nursery crops, she’s observed abnormal stem and leaf growth such as downward twisting, parts of leaves fused together, loss of apical dominance and abnormal vein formation that curls around itself.

Besides the technical expertise, Black needed an expert that could help calculate the dollar amount assigned to the drift event.

Black’s attorney hired Stephen Ford, who consults as an expert witness in litigation involving agricultural damages. He’s also an ag economist and a farmer.

“When it comes to figuring out dollar amounts for losses, you need someone who understands production nursery economics and someone who can come up with a proper calculation and a defendable number,” Black says.

The grower who incurred damages has to come up with a dollar amount that makes their situation whole, but “don’t ask for the moon and the stars when you’re not really due the moon and the stars,” Ford says.

On the other hand, don’t sell yourself short. There are a lot of costs involved that growers may not have considered, he adds.

“In some cases, there may be a cost of delaying the harvest, the cost for carrying over the crop for another year, or the cost of a delayed subsequent crop,” Ford explains. “A grower may decide to sell the damaged product or sell it as a less than optimal time, which lowers his market price. There’s also the possibility that a buyer finds out about the damage and labels the grower as an unreliable supplier and you lose their business. And make sure you’re keeping track of all your time and your staff’s time that’s dealing with this issue. Know how many man hours you’ve spent on this event.”

Even if you’re not taking legal action, all these costs are necessary to understand and track if you’re presenting them to the offender or an insurance company.

“Know the costs of doing business so you can come to a solution and a resolution,” Ford says.

Sometimes your own records are what makes or breaks the case in a drift event.

Black noticed some discrepancies in the weather conditions that were noted in the farmer’s spray records when he reviewed them with his attorney. Black had his own meticulous spray records, but he needed more proof beyond the he said/he said argument.

The day the farmer allegedly sprayed, Black hosted a tour group on his property that had a professional photographer in tow. The camera tagged each photo with geolocation and time/date stamps. When Black obtained the photos, it was obvious that the sky was cloudy, it was windy (trees and people’s hair indicated the wind direction) and the ground was wet. What was apparent in the photos did not match up with the applicator’s spray records.

“Besides your own records, you need as many sources of data that you can possibly collect when you’re trying to remedy spray drift from somewhere outside your own property,” Black advises.

Most of Black’s crop eventually recovered, but he lost an entire year of growth and still had to pay all the production and management expenses of caring for the trees, along with extending production time in the field.

“With the oaks especially, it was like they just stood still for a year,” Black says.

There were a few trees that had to be culled when they developed cankers and bark splits, but it wasn’t a large amount.

“Even though the experts we talked to said the trees would eventually be fine the following year, I was fully prepared to send checks to customers if the trees didn’t leaf out. I made sure we could do that, but it could have been a business-ending decision,” he recalls.

It was a tough lesson and one that still leaves him with a pit in his stomach.

“It killed me to have to take legal action but the damages were huge and I have a responsibility to everyone who works here to keep the company afloat,” he says.

Betula populifolia 'Whitespire' showing symptoms of excessive and premature leaf drop or senescence in the lower 40% to 50% of the crown. Although some leaf drop is normal with this species, the amount shown here is caused by increased susceptibility to drought and in this case a symptom of 2,4-D drift, group 4 MoA.

Lessons from the field

After going through a drift event, Black wishes more people in the industry talked about this issue and how it affected their nursery.

“If I had known about other people’s experiences with herbicide drift, it would have made my handling of it much better because I was figuring it out from a blank slate,” Black says. “That’s why I think it’s important for people to talk about this issue and help fellow growers through it when it happens to them.”

Besides the reactive lessons, Black learned there are proactive ways to deal with a drift event.

First, have open communication with your neighbors and know what they’re growing and spraying.

“Make sure all of your adjoining landowners understand you produce ornamental crops that are sensitive to herbicides,” Black says. “I send out a letter every spring reminding our neighbors that we grow an ornamental crop and they are sensitive to herbicides.”

Next, register your property at Drift Watch (

Drift Watch provides a directory of state sensitive crop registries and sells field signs that you can place along your property. Black registered his farm, including his USDA-certified organic trees.

“Professional applicators are supposed to check to see if there any sensitive crops in the area,” Black says. “This includes companies that spray the sides of the highways for weeds. Those are not targeted sprays, so if you’re the next farm over from the road crew, you’re going to get drift.”

Tilia cordata ‘Greenspire’ three days after drift with dicamba, showing severe leaf folding and cupping in top of crown, stems are twisted and main growing point stem is distorted downwards, yellowing and epinasty of stems are all pronounced 3 DAT. Plants tested positive for dicamba.

Each one of Black’s applicators is a licensed applicator, and the nursery keeps scrupulous records, he says.

“With a drift event, you have to first prove you didn’t cause the damage yourself by showing your spray records with your neighbors and investigators. These are contemporaneous notes and have much more validity than someone’s recollection.”

Scout your crops regularly so you’ll know at the earliest opportunity when you’ve had a drift event.

“If you don’t realize it until two weeks after the drift event, you may not be able to detect the herbicide in the soil,” he explains.

Black also added herbicide drift detection plantings along the perimeter and of the property and inside the farm, including grapes, forsythia and some legumes like soybeans and sunflowers.

“Grape foliage will show Dicamba and 2,4-D symptoms basically the next day after a drift event,” he says. “What you use in those detection plots may vary by state, so ask your extension agent what to plant.”

Everyone in the field has a phone with a camera, and now when a neighbor is spraying, someone on the crew takes a picture of the sprayer, takes a photo of a larger view of the area of the nursery, checks the weather app and takes a screen shot of it to record temperature, wind speed and other factors.

“They have those photos in case we ever need them. It only takes a few seconds to do it and we have the record. 2017 was a scary year, but we’re now loaded for bear if it happens again,” he says.

Another lesson Black wants to drive home: As a nursery grower, there is no problem coexisting with ag. But it’s important to be a good neighbor and keep the lines of communication open.