Dicamba Might Be Even More Dangerous Than Glyphosate

Dicamba Might Be Even More Dangerous Than Glyphosate
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After more than forty years, farmers using Monsanto’s glyphosate-based Roundup herbicide recently encountered a problem: weeds were becoming resistant to it, making glyphosate no longer an effective treatment.

Experts have long awaited this day.

“When they first came out with seeds that were genetically engineered to resist glyphosate,” says Mark Kastel, co-founder of the organic watchdog group the Cornucopia Insititue, “The question wasn’t if – the question was when would these crops develop resistance to this almost universally used herbicide.”

This is the issue that was outlined by the Washington Post in a recent exposé, writing, “Farmers are locked in an arms race between ever-stronger weeds and ever-stronger weed killers.”

Enter dicamba: a chemical that was supposed to be industrial ag’s saving grace. The older herbicide had apparently been reformulated to be better, stronger, and safer than both previous dicamba formulations and glyphosate. But the unfortunate reality is that dicamba has turned out to be a farmer’s worst nightmare.

The Dicamba Crisis

The newest formulation of dicamba was first approved for use this spring, designed to guarantee control of herbicide-resistant weeds in soybeans and cotton when used in combination with genetically engineered dicamba-resistant seeds. According to Monsanto, which markets the herbicide under the brand name Xtendimax, more than 20 million acres of these seeds were planted this spring and summer.

But dicamba has posed new problems for farmers, namely the fact that it volatilizes when applied to crops, revaporizing and traveling from the fields where it is sprayed to non-GMO fields.

“This material actually becomes airborne in molecules that are much smaller than are being actually sprayed on crops,” says Kastel. “It can move great distances and cause a tremendous amount of damage to crops that are particularly sensitive to this chemical.”

This has resulted in the damage of more than 3.1 million acres of soybeans according to Kevin Bradley, a University of Missouri researcher, or almost 4 percent of all U.S. soybean acres.

American Soybean Association President Ron Moore noted in late September that there are currently 2,242 complaints related to dicamba in 21 of the 30 American soybean-growing states.

“We expect that number to continue to rise,” he says.

The crisis has led to lawsuits, investigations, and an argument that ended in a farmer’s shooting death and related murder charges, but believe it or not, farmers aren’t the only ones experiencing issues related to dicamba. NPR reports that at a meeting of Arkansas’s Plant Board in September, Richard Coy, who manages 13,000 honeybee hives in Arkansas, Missouri, and Mississippi, reported that honey production fell by 30 to 50 percent in areas where farmers were spraying dicamba, as native plants were being affected, thus depriving the bees of essential sustenance.

How Did This Happen?

According to the Post, some experts claim that the herbicide was approved without enough data on possible drift, but Kastel says that on the contrary, the risks were known.

“There were warning flags raised before these materials and crops became widely adopted, and they were ignored,” he says.

Even the Post notes that according to a 2004 assessment, dicamba is 75 to 400 times more dangerous to off-target plants than glyphosate, particularly to non-GMO soybeans. In addition, the newspaper reports that in a July 29 call with the EPA, a dozen state weed scientists shared their “unanimous concern” over the volatility of dicamba: some field tests show that dicamba is volatile for as long as 72 hours after spraying.

Others have linked the increased problems related to dicamba with the fact that it is being used for the first time in summertime, promoting even worse volatility than has been seen before.

Monsanto, however, claims that the issues do not lie with the formulation of the herbicide, but rather with its application by farmers. Scott Partridge, Monsanto’s vice president of global strategy, claims that farmers have illegally sprayed older dicamba formulations or used the herbicide with the wrong equipment, and the company has deployed agronomists and climate scientists to visit growers and find out what went wrong.

Meanwhile, dicamba has been banned by regulators in some states where damage is most widespread, including Arkansas, where the State Plant Board voted unanimously to ban the use of dicamba from mid-April to November. Rules have also been tightened in Missouri and Tennessee to help stem the issues related to the herbicide.

“It’s really hard to get a handle on how widespread the damage is,” Bob Hartzler, a professor of agronomy at Iowa State University, told the Post. “But I’ve come to the conclusion that [dicamba] is not manageable.”

Not Only Unmanageable: It’s Ineffective

The worst part? It seems dicamba won’t be solving the glyphosate-resistance problem. Researchers have already shown that pigweed, one of the main targets of dicamba, can develop resistance to the herbicide within as few as three years.

“We’re on a road to nowhere,” Nathan Donley, a senior scientist at the Center for Biological Diversity, told the Post. “The next story is resistance to a third chemical, and then a fourth chemical — you don’t have to be a rocket scientist to see where that will end.”

While experts continue to seek out a new chemical solution, the underlying issue seems obvious, at least to Kastel.

“We want really cheap food,” he says. “We don’t put a value on environmental protection or necessarily food quality or safety. Whatever the minimum that you can get away with is is generally incorporated, and in this case, at least for the person applying this chemical, the costs are lower.”

But while immediate financial costs may be lower, the environmental costs are astronomical. They may be more expensive to implement, but natural weed management techniques used in organic farming, including crop rotation and the use of cover crops, do not call for genetically engineered seeds and dangerous herbicides like dicamba and glyphosate.

While we’re a long way off from seeing these techniques used in a widespread manner, it’s worth adding these solutions to the conversation, or risk being caught in an eternal cycle of even more resistant weeds and even more dangerous chemicals to attempt to control them.

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Emily Monaco
Emily Monaco

Emily Monaco is an American food and culture writer based in Paris. She loves uncovering the stories behind ingredients and exposing the face of our food system, so that consumers can make educated choices. Her work has been published in the Wall Street Journal, Vice Munchies, and Serious Eats.