Normally, Story County, Iowa, soybean farmer Kevin Larson said, he would resolve a dispute with a neighbor privately. Instead, he went to the Iowa Pesticide Bureau in 2017 when he suspected a powerful herbicide drifting from a nearby farm damaged his crop.

Other soybean farmers IowaWatch spoke with in Iowa are doing that, too.

They increasingly are filing complaints with the state’s Pesticide Bureau about drifting herbicides, some with hopes of securing tighter regulations of powerful weed killers containing dicamba.

“That’s the only way to get them to listen to you,” Larson, who farms near Story City, said.

The state and federal government have not implemented the temperature and date cut-offs for dicamba application that some farmers believe are necessary to reduce drift damage. Rather, state guidelines require applicators to follow the existing instructions on pesticide container labels, which are regulated by the U.S. Environmental Protection Agency.

With the introduction of new dicamba-based herbicides in 2017, the Iowa Pesticide Bureau reported a 69.7 percent increase in complaints about the pesticide drifting from 2016 to 2017, and a 2 percent increase from 2017 to 2018.

Dicamba is the active ingredient in a variety of name brand herbicides, notably Engenia and Xtendimax. Dicamba drift has been a concern since the first dicamba herbicide was registered for use in the United States in 1967.

Despite dicamba’s volatility, the EPA has approved three new dicamba formulas — BASF’s Engenia, DowDuPont’s FeXapan, and Monsanto’s Xtendimax — for use in the 2017, 2018, 2019 and 2020 growing seasons.

Larson, who has farmed for 40 years, used a dicamba herbicide and planted corn in the 1980s. He planted dicamba-resistant soybeans when they became available a few years ago. (Editor’s note: this paragraph was corrected April 15, 2019, after the original story was published.)

Contamination from misapplied dicamba-based herbicide in the center rows of a soybean field, compared to healthier plants on either side. Credit: Iowa State University Weed Science photo

Larson filed a dicamba drift complaint with the Iowa Department of Agriculture and Land Stewardship’s Pesticide Bureau in 2017 that resulted in a warning issued against applicator and farmer Randall Collings, bureau records IowaWatch examined show. The complaint alleged that the herbicide containing dicamba heavily damaged Larson’s soybeans. It was resolved with the warning.

It wasn’t the first time Larson had problems with herbicide drift. A field belonging to his son, who farms in Story County, was damaged by drift from an adjacent Monsanto test field in 2016. Larson said his family contacted Monsanto when drift from the herbicide began harming their soybeans. He said Monsanto inspected the damaged crop, but said drift was not responsible.

“Monsanto said it was something we’d done,” Larson said.

But an Iowa State University extension officer who assessed the damaged soybeans said drift from Monsanto’s herbicide was at fault, Larson said. The officer called Monsanto, he said.

“And not 20 minutes after that Monsanto was on the phone with us offering to make a settlement,” Larson said. Larson said his son reached a private settlement with Monsanto, but that he was unable to disclose details because of a non-disclosure agreement that was part of the settlement.

Larson said he didn’t have problems with dicamba in 2018.


Instructions for applying dicamba direct applicators to spray it in June and July. Larson said spraying in the spring is less harmful because drift is more likely in the warmer summer months.

Bob Hartzler, Iowa State University professor of agronomy and extension weed specialist

Iowa State University extension weed specialist Bob Hartzler said 90 percent of the 2017 drift complaints filed after June 15 of that year were about dicamba applications. The volatile nature of the dicamba plays a significant role in its destructive impact on soybeans.

“That’s what differentiates dicamba from other products. If you do a good job in paying attention to the environment and adjust your sprayer right there’s minimal risk of problems, but with dicamba a person would do everything right … and still have problems,” Hartzler said.

Chad Hibma, a farmer in Dickinson County, filed complaints with the pesticide bureau in 2017 and in 2018. Hibma, who has been farming for 25 years, said his 2017 and 2018 complaints concerning dicamba drift are the only ones he’s filed with the pesticide bureau.

Normally, he said, he would settle a drift problem one-on-one, without getting the bureau involved.

“If it wouldn’t have been dicamba, I wouldn’t have done it,” Hibma, whose farm is near Harris by the Minnesota border with Iowa, said.

Dicamba is different, he said, because of it lacks regulation he’d like to see. Regulation should begin at the federal level, he said.

“I don’t think the state are willing to step in and mess with Monsanto too much,” Hibma said. “I don’t think it should be banned,” he said about using dicamba, “I just think it should be (sprayed) earlier, basically. There are a lot of no-tilling guys that need it.”


Much of the spraying in Iowa in the last two years has been done by professionally trained applicators.

Keely Coppess, communications director for the Iowa Department of Agriculture and Land Services, said the state began in 2018 requiring licensed dicamba applicators to receive dicamba-specific training.

“This training is separate and distinct from the pesticide applicator continuing instruction courses required by the U.S. Environmental Protection Agency (EPA),” Coppess wrote in an email to IowaWatch.

Hartzler and ISU Extension and Outreach’s weed management specialist Kristine Schaefer helped the state ag department develop the new dicamba training curriculum.

Additionally, the EPA restricted the conditions suitable for dicamba application for the 2019 growing season.

“IDALS believes these changes adequately address drift concerns while giving farmers access to a variety of weed-control solutions,” Coppess wrote.

These regulations do not address Hartzler’s hope that Iowa join Arkansas, Illinois, Minnesota, North Dakota and South Dakota in enforcing its own date and temperature cutoffs for dicamba application. Hartzler said the state might be reluctant to implement its own application regulations because it’s easier to let that burden fall on the EPA.

Near the end of March, the EPA announced that it may begin restricting the ability of states to place certain limitations on pesticide use.


Because dicamba is prone to drift, researchers at Iowa State University Weed Science — part of the Iowa State Extension and Outreach office — recommends dicamba be sprayed before soybeans begin emerging from the soil. Where that isn’t possible, Hartzler said, “The earlier you can apply it the less risk there is.”

Hartzler has advocated for a mid-June cut-off on dicamba applications.

Larson went a step further. He said the state or federal government should not allow the use of dicamba because it’s so prone to drift.

Tony Blue, a farmer in Hamilton County near Kamrar, filed a complaint with the Pesticide Bureau for the first time in his life in 2017. In addition to growing soybeans, Blue sells pesticides.

“As far as post application I think there’s always going to be a risk,” Blue said about dicamba. “I’m a person who sells chemicals myself and a lot of the folks I deal with, they’re just steering clear of it and they’re not spraying it themselves.”

Tony Blue and his family at their farm near Kamrar, Iowa. Left to right: stepson Eric Dowe, Blue, wife Christine Semler-Blue, sons Connor Blue (holding family dog, Duke) and Tanner Blue. Credit: Photo by Jenny Walker shared with IowaWatch

Blue said he filed his 2017 complaint because it was the first time he had severe problems with the powerful herbicide drifting from a neighbor’s field. Blue said five of his soybean fields sustained considerable damage so he turned to the Pesticide Bureau for help. The applicator in his case received a warning, bureau records show.

Blue said he did not have any problems with dicamba drift in 2018.

Occasional drift happens, damaging a row or two of crops along the edges of a field. Most farmers will tolerate that, Blue said.

Still, the risk exists.

“Our situation involved multiple fields, and not just along field boundaries,” Blue wrote in an email to IowaWatch. “We had multiple fields where you could visually see the effects of the dicamba drift a quarter mile out into our field.”


This story republished by The Des Moines Register under IowaWatch’s mission of sharing stories with media partners.

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