STEVE INSKEEP, HOST:
There's a weed in Arkansas that can put a farmer out of business. It's called pigweed. You get one plant in your field, and that one plant can produce more than a million seeds. Many of the seeds become new plants that can choke your fields. Arkansas farmers are in a constant battle with pigweed. And last year, that battle pitted farmer against farmer. Marianne McCune from our Planet Money podcast has the story of how a war with a weed led to murder.
MARIANNE MCCUNE, BYLINE: Mike Wallace was shot dead last October on a quiet county road at the edge of his field. His widow, Karen, and their son are still growing cotton and soybeans, keeping their heads up - even without Mike.
KAREN WALLACE: Well, it's hard, but we're pushing through it.
MCCUNE: We sit down in Karen's spare and orderly office to talk about how on earth a war with pigweed could have led to Mike's death. I spot him in a family photo - square jaw, buzzcut, kind of a Christopher Reeves smile.
WALLACE: My husband, if he was driving down the road and he saw pigweed out there, he would walk to the end of the field and get it and drag it out to the end. I mean, he was just not going to leave the pigweed in the field.
MCCUNE: Like most people around here, Mike also used pesticides. And in the 90s, when the first genetically modified cotton seeds came on the market, he planted those too. Those seeds were engineered with a genetic trait that protected them from a very powerful herbicide called Roundup. The seeds and the chemical were sold together. The Wallace's crop consultant Dave Pierce says it was huge. You could spray Roundup on your Roundup-ready cotton fields, and only your weeds would die.
DAVE PIERCE: Roundup made a lot of people good farmers. It was a once-in-a-lifetime chemistry. I mean, we depended on it for years and years. And we depended on it too much.
MCCUNE: Too much because after a decade or so, the pigweed did its own genetic morphing and became immune to Roundup.
PIERCE: Mother Nature's pretty sharp.
MCCUNE: Two years ago, the big chemical companies came out with a new seed to go with a different herbicide called Dicamba. And it looked like farming might get easier again. Except, the new Dicamba spray they planned to sell with the seeds wasn't approved yet. There was an old formulation of Dicamba, but it was especially prone to drift onto other fields.
So it might kill your weeds but also your neighbor's crops. Now, Mike's cousin, Maleisa Finch, runs a cotton processing plant just down the road, and she told me farmers have always dealt with some drift. They just talked it out.
MALEISA FINCH: The one that had the damage would say, hey, I think you might have gotten me the other day. The one that did it would say, man, I'm sorry. Let me know, and I'll pay for that.
MCCUNE: But in the case of Dicamba, talking didn't seem to work - maybe because it was actually illegal to spray that old formulation of Dicamba during growing season. And yet, once farmers started planting those Dicamba-tolerant seeds and saw that nasty pigweed invading their fields, some of them just couldn't resist spraying a little Dicamba on top - legal or not.
FINCH: Mike's fate was sealed the day that first bag of seed went out.
MCCUNE: When Mike saw the leaves on some of his cotton curling and puckering from Dicamba, he, like many farmers, filed a complaint with the Plant Board. They're like the pesticide police. And they tracked the cause of Mike's damage to a neighboring farmer, Donald Masters.
Hello, Mr. Masters?
First member of the Masters family I encounter is Douglas - in his 50s, big beard, wild hair.
Can I talk with you?
DOUGLAS MASTERS: What do you need to know?
MCCUNE: I need to know...
I ask him about the Plant Board's visit to this farm looking for Dicamba.
DOUGLAS MASTERS: Yeah, everybody got in trouble.
MCCUNE: And did you know that you weren't supposed to be spraying it?
DOUGLAS MASTERS: (Laughter) You want admission of guilt, don't you?
MCCUNE: No, I actually really want to understand it. What I want - like, is the economics - I want to know like...
DOUGLAS MASTERS: It goes back to economics.
MCCUNE: So tell me. What was going on here economically, and what...
The economics, he tells me, was this. Farmers take out huge loans every year to pay for seeds, pesticides and everything else. And with crop prices low, their profit margins are very thin. He says when the pigweed started threatening his crops, they needed a cheap and effective solution.
DOUGLAS MASTERS: The only option we were left with was to put Dicamba out there.
MCCUNE: Pretty soon, Douglas' dad shows up with white hair, eyes that look like they've been peering into the sun for 70-plus years. He climbs into a huge red tractor.
(SOUNDBITE OF TRACTOR)
MCCUNE: I head over.
Can I come up?
And have to climb up six steps to reach him.
DONALD MASTERS: Do what now?
MCCUNE: So I was just wondering, you know, it looked like from the Plant Board record I saw in Arkansas, that you were accused of spraying Dicamba when you weren't supposed to and...
DONALD MASTERS: I did.
MCCUNE: And why'd you do that?
DOUGLAS MASTERS: Why'd I do it? Because I've got weeds you can't kill otherwise. But anyway, I paid the fine - and supposed to be done with, I hope.
MCCUNE: The maximum fine at the time was $1,000. But a farmer could save tens of thousands of dollars by using the cheap Dicamba. The following year, 2016, farmers in the region saw damage on nearly 200,000 acres of crops - millions of dollars' worth. And Mike Wallace continued to speak out. Masters had stopped using Dicamba, but others continued.
Mike's complaint to the Plant Board that summer led investigators to another farm. Documents show that farmer contested the accusation and refused to give over his pesticide records. Tensions were still high after harvest. That's when farmers find out how much the damage is worth. It was then that for reasons Mike's family members say they don't know, Mike got a phone number for a young employee of that second farm. The two men met up to talk on that quiet county road, and things got out of control.
(SOUNDBITE OF ARCHIVED RECORDING)
UNIDENTIFIED REPORTER: We have continuing coverage tonight after a man in Mississippi County was arrested after reportedly shooting and killing another man.
MCCUNE: Karen Wallace says more than a thousand people showed up for her husband's funeral at their church.
WALLACE: We wanted tractors around the cemetery, and there was probably 15 or 20 tractors that people brought their equipment and lined it up.
MCCUNE: There are a lot of ways to think about why a pesticide dispute led to a murder. Some fault the low fines for illegal spraying. Arkansas is raising them. Missouri's largest peach farmer is suing the company that first put out Dicamba-tolerant seeds without the new spray to go with it. That company is Monsanto, and they say the suit is baseless, that it's not their fault people sprayed a chemical they weren't supposed to.
Monsanto warned people not to do it. There is a new, approved Dicamba on the market that's not supposed to drift so much. But there are already reports of damage to crops, whether from legal or illegal use. And weed scientists have a longer-term worry that once everyone starts using Dicamba like they used Roundup, the pigweed will play that trick of Mother Nature and become resistant again. For NPR News, I'm Marianne McCune.
(SOUNDBITE OF JON HOPKINS' "LOST IN THOUGHT")