In dealing with climate change, farmers see paraquat as “essential”

By Syngenta Group News Service
May 2023

Growing up on a small farm in Illinois, Larry Steckel spent many long summer days crouched on the ground, yanking out weeds by hand to protect his family’s treasured soybean and corn crops.  

“I remember looking at what seemed like endless rows of weeds that we were trying to chop because there weren’t any herbicides that would control them,” Steckel said. “It was all manual labor. And I thought to myself then, ‘There’s got to be a better way.’”  

That search for a better way—for new tools and practices that would make farming more efficient and economically viable for farming families like his own—inspired Steckel to earn his PhD in crop sciences and embark on a career in weed science. These days, as a professor and extension weed specialist at the University of Tennessee, he helps farmers throughout that state navigate the persistent challenge of weed management. 

It’s a struggle that continues to evolve, as weeds develop resistance to certain herbicides and as unfamiliar weeds emerge amid changing weather patterns brought on by climate change. Left unchecked, weeds can devastate a crop. They grow quickly and pull in moisture and nutrients from the soil for themselves, robbing crops—which grow more slowly—of what they need to be healthy. When weeds grow tall enough, they also capture the sunlight that crops require. 

And yet, one herbicide in particular has done more than any other to transform weed management—not only for farmers in Tennessee, but worldwide—since the summer days of Steckel’s childhood. That is paraquat, a fast-acting herbicide that’s effective on a broad range of weeds and in a variety of weather conditions. 

“It’s the only herbicide that still works on the weeds that are there at planting, and that's so, so critical in this state,” Steckel said. “You won't raise a crop if you get weeds that are up with the crop. They'll just eat it. It just will completely outcompete them when they've got a head start.”  

Champions and critics  

Paraquat is an herbicide that is widely used. It’s rainfast, so it doesn’t need to be reapplied even if it starts to pour half an hour after spraying. It’s effective on weeds that can hamper a wide range of crops—whether soybeans or cotton, watermelons or grapes, or virtually any of the other types of plants that farmers cultivate. And paraquat is cost-effective, making it a viable option for smallholder farmers and during economic crunch times.  

Crucially, too, paraquat immediately becomes inert upon contact with soil, so it does not run off into waterways or threaten groundwater and streams. And it allows farmers to preserve the structure, quality and biodiversity of the soil—which is any farmer’s most precious resource.  

In recent years, paraquat has been in the news with some frequency—often in negative ways.  

Paraquat is acutely toxic, if ingested. There are strict guidelines in place to ensure its safe use—including warning labels and mandated safe-handling courses that raise awareness of this danger and that emphasize the risks of transferring paraquat into non-authorized containers.  

Sadly, there have been instances in which people were harmed after consuming the product, for example after mistakenly sipping from soda bottles or other daily-use containers that someone else used to fill with the product—in clear violation of regulations. To reduce the likelihood of such accidents, Syngenta’s paraquat formulations contain blue dye to distinguish it, a stenching agent to make it obvious it is not a beverage and an emetic to induce vomiting when ingested. 

Meanwhile, a large body of scientific research has explored whether—as some critics have contended—there is a connection between paraquat use and Parkinson’s disease, a debilitating neurological disorder. However, no peer-reviewed research has ever concluded that paraquat causes Parkinson’s. The theory that paraquat causes Parkinson’s is not accepted by the medical or scientific community. In fact, a recent review of the scientific literature, published in the journal NeuroToxicology, found that “a consensus exists in the scientific community that the available evidence does not warrant a claim that paraquat causes Parkinson’s disease.”   

Unfortunately, plaintiffs' lawyers have seized on paraquat as their next cash cow—spending millions of dollars in advertising on television, radio, online and direct mailings to recruit people who may have used the product.   

Plaintiffs' lawyers have even targeted home gardeners with direct emails, banner ads on gardening websites and social media advertising, encouraging them to join the lawsuit. In the U.S., no paraquat products have ever been sold for home and residential use. Plaintiffs’ counsel have also aired myriad ads and solicitations urging golf course employees to file claims. In fact, paraquat use on golf courses is prohibited by law.    

EPA cites paraquat’s “unique and often high benefits”  

In the U.S., farmers like those Larry Steckel advises have closely watched the U.S. Environmental Protection Agency’s (EPA) registration review of paraquat. In July 2021, the EPA announced that after a lengthy examination, paraquat could remain on the market with new safety measures in place.  

Paraquat has “a number of unique and often high benefits” for crops, the agency found. Referring to the newly mandated safety measures, the EPA added: “Any potential risks of concern that aren’t fully mitigated by the measures discussed herein are outweighed by the benefits associated with the use of paraquat.”  

The updated safety measures include restrictions on how long farmers must wait to enter a field after paraquat is applied; weather-related and spraying restrictions designed to minimize the amount of paraquat that drifts away from a target area (for example, paraquat cannot be sprayed on extremely windy days); and additional warning labels.  

A tool for environmental sustainability  

Often, policy debates about chemical regulations boil down to battles between two clearly delineated camps: environmentalists seeking greater restrictions versus business interests seeking fewer. When it comes to paraquat, however, the picture is much more complicated.  

Consider, for example, the role of paraquat in the public conversation about climate change—an issue that often pits environmentalists against industries. 

Although the agriculture industry is estimated to generate 12% of global greenhouse gas emissions, there is a growing movement to leverage the industry to drive change on behalf of the environment. This has been a theme at global conferences, including COP27 and the World Economic Forum.  

At these gatherings and in other forums, business leaders and policymakers are expressing growing optimism about the potential impact of “regenerative agriculture”—a science-based, outcome-driven approach to farming that places a priority on the nurturing and restoration of soil health and biodiversity. Healthy soil is critical to this environmental conversation because it is less prone to erosion, better able to capture carbon from the atmosphere and keep it locked beneath ground, and conducive to high crop yields (eliminating the need to clear natural vegetation to produce enough crops to feed the world’s growing population).  

One of the key tenets of regenerative agriculture is no-till farming. When farmers use heavy machinery to till their land between planting seasons, they do eliminate harmful weeds—but they also disrupt soil structure, releasing carbon into the atmosphere and accelerating erosion. Paraquat is a quick, safe, easy and uniquely effective alternative to intensive tillage—allowing farmers to rid their fields of weeds while preserving the quality of their soil.  

In Tennessee, many farmers began adopting no-till practices in the 1980s, following decades of heavy erosion.  

“I've seen data from back in the ‘70s, where in the state of Tennessee we were losing 40 tons of topsoil per acre per year,” Steckel said. “Our fields were literally washing away, down the Mississippi to the Gulf of Mexico. It was terrible on the landscape and environment here then, and it was terrible on the environment down in the Gulf of Mexico. You just can't move all that material down and not affect a lot of wildlife, people, the whole river system.”  

“If we don't have paraquat, we're all going to have to revert back to tillage,” Steckel said. “And that really is a non-starter here for us.”  

A global solution  

Steckel’s views on paraquat are echoed by farmers around the world. The changing and extreme weather patterns caused by climate change make farming ever more challenging. And in many places, farmers face additional pressure to cultivate crops in a more environmentally sustainable way.  

In Indonesia, rice farmers like Wahyudi have seen yields improve and expenses decline after turning to paraquat. Wahyudi has been cultivating rice in the East Lampung region since 2012, when his grandfather passed along the treasured family fields that he could no longer work himself. Wahyudi began using paraquat about eight years ago, he said.  

Paraquat saves on labor costs, Wahyudi said, and does not harm the plants that grow after it is used. “It is very helpful for farmers, especially in controlling weeds at the beginning of the process before planting,” he said. In Australia, paraquat has been critical to helping third-generation farmers like Andrew Weidemann, of the southeastern Victoria state, stay in business despite crushing droughts. By using paraquat in combination with other products, Weidemann has been able to avoid tilling—which helps maximize his soil’s ability to retain every drop of water available.

“If we were going to go back to a tillage situation, if we lost access to paraquat, then we would really be in all sorts of strife,” Weidemann said. “There's no question about the loss of productivity.”

For Weidemann, the appeal of the farming life is not just about a love of the land, or the satisfaction of maintaining family traditions. There’s also pride in the part he plays in nourishing the growing world population.

“It's such a fantastic industry,” he said. “Why wouldn't you want to be involved in it—producing food for the rest of the world?” “We actually have to increase our productivity more than by more than a third again today, to just to feed the population that's expected in another 20 years,” Weidemann continued. “We've really got to lift our game.

“And the thought of not having products like paraquat in our rotations,’’ he said, “it would be a real problem for us.”

Tim Durham, a seasonal vegetable farmer at Deer Run Farms, in New York, and an associate professor of crop science at Ferrum College, in Virginia, described paraquat as “essential.”

“The major environmental benefit really stems from a no-till approach to farming,” Durham said. “The fact that the ground can stay intact without disruption, build that organic matter, build that surface organic material—that essentially not only limits erosion, but limits the amount of evaporation from the soil surface.”

Durham said he has “no qualms about using paraquat, provided the labeled guidance is followed—in terms of personal protective equipment, mixing and an air gap between our fill tank and water source (to prevent backflow).”

“Paraquat, first and foremost, is a restricted-use pesticide, so you must be a licensed applicator to apply this material,”

Durham explained. “In addition, there's a secondary level of precaution—a whole other layer of instruction that a potential applicator must go through to be certified.” Durham explained that he sees paraquat as “almost like a prescription, in many respects.” Like many medicines that doctors prescribe for their patients, paraquat can have transformational results—but must be used as directed.

“This is not something that you can get over the counter,” Durham noted.