The dicamba herbicide was supposed to solve weed problems farmers suffer – instead, it makes farming more difficult for many of them

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(The Conversation) In October 2021 I was a guest on a popular podcast discussing my recently published book, “Seed Money: Monsanto’s Past and Our Food Future,” which examines the agribusiness giant’s impact on the global food system. After the show, I got a lot of calls from all over the world, but one of them really stood out to me: a farmer talking on his cell phone from his plantation bench in South Dakota while he was harvesting soybeans.

Farmers don’t like to park the tractors on days when the weather is fine in the fall, but this was important. The caller wanted to talk about a chemical herbicide called dicamba that was being sprayed in the nearby fields. He claimed it was damaging his crops. And he was not alone.

In 2021, thousands of American farmers reported to the Environmental Protection Agency that Dicamba sprayed by other farmers—sometimes a mile and a half away—damaged crops in their fields. Complaints came from all over the country.

And the list of infected plants was amazing: sycamore, oak and elm. Azaleas, black-eyed Susans and roses. Tomatoes, peppers and peas. According to an EPA memo, there were 2,700 “Dikamba accidents” that affected about 3.6 million acres in 2017. Two years later, the number of accidents had risen to 3,300.


This problem has been piling up for more than five years, and the Environmental Protection Agency acknowledges that the modest controls it requires, such as creating buffer zones around fields, are not working. But stricter restrictions on the use of dicamba are unlikely before the start of the 2022 growing season in the spring, as it would require complex legal procedures.

Why is it difficult to address this national problem? Answering this question requires looking back to 1996, when the revolution transformed American agriculture.

From a news report to Dicampa

Weeds have always been an expensive nuisance to farmers. A 2016 study estimated that if weeds were left unchecked, it would roughly halve North American corn and soybean crops, causing annual economic losses of US$43 billion from just those two crops. One problem farmers face is that weeds are too good at developing resistance to the chemical products used to kill them, so herbicides lose their effectiveness over time.

Weed problems became especially bad in the late 1980s and early 1990s as widely used herbicides called ALS inhibitors became less effective. That’s why farmers were so excited about Monsanto’s “Roundup Ready” crops, which were first introduced in 1996.

These plants are designed to withstand the heavy spraying of Monsanto’s massive herbicide, Roundup. Monsanto developed and patented glyphosate, the active ingredient in Roundup, in the 1970s, but the advent of Roundup Ready seeds made glyphosate sales explode.

It seemed like a magical system: farmers could treat fields with glyphosate throughout the growing season without harming their crops. For a few years, herbicide use in general declined: farmers used glyphosate in large quantities, but they stopped buying most other herbicides.

Monsanto emphasized that this approach would make farming more sustainable by reducing long-term use of herbicides and pesticides — especially older, more toxic brands. However, the system soon began to falter.

In the early 2000s, scientists began to report that the weeds were developing resistance to the Roundup Channel. In response, Monsanto introduced a new generation of genetically modified seeds that would make crops resistant to a greater range of older herbicides. Growers can use these older products in conjunction with Roundup, which improves their chances of killing most weeds.

One of the chemicals Monsanto bet on was dicamba, which was first introduced in the 1960s. In 2015 and 2016, the company began producing “Roundup Ready Xtend” branded seeds that were designed to withstand heavy spraying of both dicamba and glyphosate. The reasoning was that dicamba would eliminate glyphosate-resistant weeds, and that glyphosate would eliminate all other unwanted plants.

The solution becomes a problem

It soon became clear that this fix was seriously flawed. Dicamba is one of the most volatile herbicides on the market, which means that it changes easily from liquid to vapor in warm temperatures. When farmers sprayed dicamba on hot days, it tended to evaporate and drift off target, dotting fields and farms often not planted with crops genetically modified to tolerate. The South Dakota farmer who called me from his harvest was harvesting organic Monsanto’s non-Xtend soybeans.

Mad farmers, Monsanto had seen it coming. In a 2020 federal court case, Farms Baader v. Monsanto, confidential company documents revealed that the company was aware that dicamba spray on Xtend crops would likely drift off target. Monsanto salespeople even called this point of sale for Dicamba-resistant seeds. A slide in a 2013 internal sales presentation suggested “Pay ‘protection from your neighbour’.”

Farmers began complaining about dicamba erosion shortly after Monsanto introduced its first Xtend seed. The Trump administration instructed farmers not to spray dicamba in buffer zones around fields, and restricted the use of dicamba to certain times of the day, but this had little effect.

Amid the controversy, the Environmental Protection Agency extended its approval in 2018 to three Dicamba-based herbicides. But the U.S. Ninth Circuit Court of Appeals overturned that decision in June 2020, ruling that the agency had ignored or downplayed evidence of harm from dicamba and failed to consider how the “social fabric of farming communities was ruptured.” In response, the Environmental Protection Agency approved the new dicamba licenses with some additional control measures that it said met the court’s concerns.

chemical arms race

Now the Biden administration is considering how to deal with Dicampa – not too soon. Farmers are said to be seeing weeds that have developed resistance to dicamba and other recommended herbicides for use with a new generation of genetically modified seeds. According to weed specialists, this happens precisely because farmers use such large amounts of these chemicals during the growing season.

Seed companies such as Germany’s Bayer, which now owns the Monsanto family of products, say one solution for farmers is to buy seeds that can tolerate a wide range of herbicides. Recently, for example, Bayer sought approval for a new batch of seeds that would make crops resistant to five different types of herbicides.

For farmers, this will mean greater reliance on an expanded range of petrochemicals, and therefore higher costs. Today, American farmers use more than twice as much herbicide to grow soybeans as they did before the introduction of Roundup Ready crops.

I see Dicamba’s drift as a symptom of the greater dependence on petrochemicals that threatens the viability of the US diet. My research in this area shows that if federal agencies really want to help farmers solve weed problems, they better look to agricultural innovators who demonstrate that crops can be grown productively and profitably without relying too heavily on synthetic pesticides.

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Growers in the United States and around the world are looking for alternative ways to deal with weeds. Some are diversifying what they grow, using time-honoured practices like cover cultivation, and looking for innovative ways out of the regenerative farming movement.

If these tools can create a future agricultural economy that is less dependent on petrochemicals derived from finite resources, I think it will be good news not only for farmers but also for those who depend on them for our food.

This article has been republished from The Conversation under a Creative Commons license. Read the original article here: https://theconversation.com/the-herbicide-dicamba-was-supposed-to-solve-farmers-weed-problems-instead-its-making-farming-harder-for-many-of-they 174181.

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