The Weedkiller That Went Rogue : Short Wave A few years ago farmers started noticing their crops were developing damaged leaves. Turns out the culprit was dicamba, a weedkiller being sprayed by other farmers. Now a trial is underway to decide who's responsible. The farmer behind the lawsuit is pointing the blame, not at other farmers, but two big companies, Monsanto (now owned by Bayer) and BASF. Follow host Maddie Sofia on Twitter @maddie_sofia. Email the show at
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The Weedkiller That Went Rogue

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The Weedkiller That Went Rogue

The Weedkiller That Went Rogue

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You're listening to SHORT WAVE from NPR.

Maddie Sofia here with Dan Charles, food and agriculture correspondent. Hey, Dan.


SOFIA: So, Dan, you've been following this really interesting story for years now. It involves farmers, scientists, a giant corporation and damage to millions and millions of acres of crops.

CHARLES: It is huge. But let me start with this one farmer...


CHARLES: ...In southeastern Missouri, a peach farmer. A few years ago, he started noticing this strange and disturbing thing. The leaves on his peach trees were just kind of curling up. He was one of the first to see this, but in the years since, there have been thousands and thousands of farmers who have seen the same thing all across the Midwest, from Minnesota in the north down to Mississippi in the south. And at this point, they pretty much know what's happening. This is damage from a particular weedkiller that neighboring farmers are spraying.

SOFIA: So other farmers spray it on their own crops, but it can travel to neighboring farms.

CHARLES: Right. And it's a specific weedkiller called dicamba which has gotten really popular just in the last few years, especially among soybean farmers. Well, that peach farmer I mentioned - he is in court right now in Missouri. He has filed a lawsuit over this.

SOFIA: And what's interesting to me is that this farmer is not suing his neighbors. He is suing a couple of really big corporations.

CHARLES: That's right, especially the company, Monsanto, which is now owned by Bayer. It's the biggest seed company in the world. He's also suing another company called BASF. Our peach farmer is saying this is not just a case of farmer against farmer. He's saying it's a case of corporate misconduct. He's arguing that Monsanto in particular put a product onto the market that it knew was going to cause all kinds of problems. And, you know, these companies - the products they're selling are worth billions and billions of dollars...

SOFIA: Right.

CHARLES: ...To them.

CHARLES: Other farmers are lined up behind that peach farmer. They filed their own lawsuits. I think it is fair to say American agriculture has never seen anything like this.

SOFIA: Today on the show, the weedkiller that went rogue and the impact it could have on how we farm in America.


SOFIA: OK, Dan, so where do we start?

CHARLES: OK. So, Maddie, can we talk about weed control here?

SOFIA: I would love it.

CHARLES: (Laughter) Farmers typically spray herbicides to kill the weeds, but the difficulty has always been through history - they're all plants. How do you kill just the plants...

SOFIA: You want to kill?

CHARLES: ...You want to kill and not, you know, the crops that you want to keep? Years ago, Monsanto came up with this invention which really has transformed modern farming, at least in the U.S. and lots of places around the world. They genetically modified their crops so that the crops were immune to a particular weedkiller - in this case, Roundup. So farmers could just spray Roundup all across the field, and their crops would survive, but the...

SOFIA: Right.

CHARLES: ...Weeds would die.

SOFIA: The weeds would die. So where does dicamba come in?

CHARLES: Well, the weeds eventually evolved resistance to Roundup, so the chemical stopped working. So Monsanto went looking for a new chemical that would basically work the same way, and they were able to do it. They modified soybean plants so those plants could resist this other weedkiller that's been around for a while called dicamba.

SOFIA: So, just to clarify, Roundup has had its own set of controversies and legal troubles for Monsanto. But today we're talking about dicamba.

CHARLES: That's right.

SOFIA: So can we talk about the science here for a moment, the gene that makes the plants dicamba-resistant? So, basically, they added a gene to these soybeans.

CHARLES: Yeah, exactly. So the initial work for this was actually done at the University of Nebraska. They found bacteria that have a gene which produces an enzyme...

SOFIA: Love it.

CHARLES: ...Which breaks down the dicamba - detoxifies it, basically.

SOFIA: Got you.

CHARLES: So they took that gene from bacteria. They inserted it into soybeans, so soybeans now have this magical property. You spray them with dicamba, this enzyme which is now in the plant - detoxifies the dicamba. The plants, you know, thrive.

SOFIA: And when did everybody start using this stuff?

CHARLES: Well, by 2017, farmers were going full tilt with this. And they just loved it, loved it, loved it. It worked really well. In 2018, I went to Arkansas and visited a farmer who farms land right by the Mississippi River named Mike McCarty. And he was telling me, you know, all about his terrible problems with a weed that they had previously not been able to control, a weed called pigweed.

MIKE MCCARTY: Pigweeds have been a major battle for us - not just myself but every farmer in this area. And we're fighting them as much as we can. We just don't have a tool in our box that will take care of it. This is the first year that we've had something that has worked.

CHARLES: So farmers were using these Monsanto seeds. They were spraying the dicamba. The weeds were dying, but that's when the problems started.

SOFIA: What kind of problems are we talking about here, Dan?

CHARLES: Well, let me take you to another field, introduce you to another farmer. His name is David Wildy - also not too far from the Mississippi River in Arkansas. He did not want to use these dicamba-tolerant soybeans. He wanted to plant different varieties. He wanted to use other herbicides. And his soybean plants, they got hit by dicamba vapor.

DAVID WILDY: You can see there that that was severely deformed, and there's just one bean in that pod, severely damaged from dicamba.

CHARLES: Where is the closest dicamba spraying to here, do you think?

WILDY: Right there.

CHARLES: Right across the ditch?

WILDY: Yeah.


SOFIA: How did Wildy know it was dicamba that was killing his crops?

CHARLES: It became pretty obvious very quickly to these farmers. There's a particular kind of signature of dicamba exposure, a particular kind of cupping of the leaves.

SOFIA: So he thinks it's probably that neighbor who uses dicamba. Did he talk to his neighbor about it?

CHARLES: Yeah - went over, talked to his neighbor, said, you know, I think you sprayed dicamba. I think it's hurting my crops. And the neighbor said, look. I followed the directions. I sprayed it exactly as the label told me to. And it's not my problem.

SOFIA: Right.

CHARLES: Your problem. And this kind of thing has been happening all up and down sort of the middle of the country.

SOFIA: Sure.

CHARLES: You know, in one tragic case in Arkansas in 2016, two neighbors were - got in a fight, and one of them pulled a gun and shot the other.


CHARLES: Killed him.

SOFIA: Didn't these same farmers use Roundup for years before dicamba? Didn't Roundup, you know, like, kind of float in the breeze and spread?

CHARLES: No. See; that's the thing. Farmers have dealt with herbicide drift before.

SOFIA: Sure.

CHARLES: And that's usually when, like, the wind kicks up and it physically blows the droplets of chemicals, you know, where they're not supposed to go. But this was really something very, very different. And the scientists at a bunch of universities started looking at this carefully, trying to figure out what was going on. And what they found was something called volatility.

SOFIA: Volatility meaning that dicamba easily becomes a vapor and can really travel some distance.

CHARLES: Exactly. What seems to be going on is after the farmer sprays it, the sun will come up, and this will evaporate...

SOFIA: Right.

CHARLES: ...From the soil, from the leaves. And if it does that, if it becomes volatile, then, like, who knows where it'll go? It'll, you know, drift in the breeze, float over to the next field, into the next woods. And researchers have come to the conclusion that is what's happening.

SOFIA: So I have to imagine this is not just a problem for farmers, right? But it could be a problem for any susceptible plants, like, including the wild ones.

CHARLES: Absolutely. I mean, that - those are effects that people are only really now starting to look carefully at. But certainly, people have noticed here and there the effects - trees in people's yards. I've seen whole rows of sycamore trees along country roads where the leaves are curled up. There's a lake in Tennessee where there's some cypress trees that seem to have clearly been affected by dicamba.

SOFIA: So what does Monsanto or Bayer say about all this, Dan?

CHARLES: Well, basically, the company says it's not happening. So in the specific case of the peach farmer, Bayer says that the farmer's peach trees actually were damaged by a soil fungus and not dicamba. And in general, the company says, you know, when this chemical is sprayed correctly, any volatility that happens will not, you know, happen so much that it causes any serious damage. They're saying, basically, you know, all these cases of damage - it's just user error.

SOFIA: Oh, so they're saying, like, it's the farmers fault.

CHARLES: They're saying farmers are either using the wrong nozzles, perhaps, or are spraying in the wrong weather conditions.


CHARLES: And they're saying, with better training, that these problems will go away or at least be totally manageable.

SOFIA: OK. But, regardless, like, there's a problem here, right? So why hasn't the EPA or any other government agency been like, hey; until we can get a handle on this, we're pulling this off the shelves. What's going on?

CHARLES: Well, so, you know, it's not just Monsanto here or Bayer. It is so many farmers that have so much invested in this technology. And, you know, the farmers that use this - a lot of them are dead set on still using it.

SOFIA: Right. Right.

CHARLES: Right? And they say, like, we have these weed problems. If we don't have a tool that works, we're going to go out of business. And there's also an undertone of, look; there's an easy solution here. Just, like, everybody get on board with this technology.

SOFIA: Got you.

CHARLES: Right? Like, you - if you planted, you know, the dicamba-tolerant soybean seeds, you wouldn't have a problem, so just, like, do it - which, as you can imagine, does not go over really well with the farmers who don't want to use or plant the dicamba-tolerant soybeans because they sort of feel like, we're being told to pay protection money, basically.

SOFIA: Yeah.

CHARLES: And honestly, I mean, you will - I have talked to farmers, people associated with agriculture, university researchers in places like Arkansas and Tennessee and Missouri who say soybeans across this entire state - you're either planting dicamba-tolerant soybeans at this point or your soybeans are showing the effects of exposure to dicamba. It is that widespread.

SOFIA: So bring us up to date on the court case. They're in the trial now. What is going on?

CHARLES: Right. They're in the middle of the trial, and there has been some evidence presented in this trial that Monsanto knew that this was likely to be a problem at least of some sort. You know, they had estimates of the amount of complaints from dicamba drift that they thought they might see. They - it seems like, from the evidence, that they actually avoided doing some tests that might have shown how big that problem might be.

SOFIA: I see.

CHARLES: So, you know, we don't know how this will play out. But, I mean, the outcome of this case will be interesting. I mean, I - you know, I've been covering this a while. I just added up the number of stories I've done on this...

SOFIA: How many?

CHARLES: ...Over the years. It's up to 16 now, I think.


CHARLES: And I've seen so many fields, you know, where this has been a problem. And there's this question of, like, is - are there so many farmers that depend on this product? And is there so much money behind it that we basically - do we just have to live with this...

SOFIA: Yeah.

CHARLES: ...At this point?

SOFIA: Right.

CHARLES: That is the question. I mean, the Environmental Protection Agency has to re-approve this at the end of this year for it to stay on the market.


SOFIA: All right. Food and agriculture correspondent Dan Charles. Thank you, Dan. I appreciate you.

CHARLES: Thank you.

SOFIA: This episode was produced by Rebecca Davis, edited by Viet Le and fact-checked by Emily Vaughn. I'm Maddie Sofia. Thanks for listening to SHORT WAVE from NPR.


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