DAVID GREENE, HOST:
Monsanto, the pioneer of genetically modified food, likes to say it is rooted in science, but some leading scientists are accusing the company of denying evidence about the risks of its newest weedkilling technology. NPR's Dan Charles has the story.
DAN CHARLES, BYLINE: The chemical that set off this war over weed science is called dicamba. It's a weedkiller sold under trade names like Clarity and Banvel, and it's advertised as the solution to a farmer's worst enemies.
(SOUNDBITE OF BANVEL HERBICIDE AD)
UNIDENTIFIED NARRATOR: If you hate Canada thistle because it costs yield, start getting even with Banvel herbicide.
CHARLES: But dicamba doesn't know the difference between weeds and crops. It can kill both. Once your soybeans or vegetables sprout, you can't spray this chemical without hurting them - unless you're using some of Monsanto's new seeds. The company has tweaked the genes in soybeans and cotton, created new genetically modified varieties of those crops that can tolerate dicamba. This year, for the first time, farmers got to spray dicamba right over their soybeans to clear out the weeds. And a lot of them did. Scott Partridge, Monsanto's vice president of global strategy, says farmers planted dicamba-tolerant crops on 26 million acres.
SCOTT PARTRIDGE: The demand for it is overwhelming. The need to control these difficult-to-manage weeds is huge.
CHARLES: But when the spring started, so did the complaints. Dicamba wasn't staying where it belonged. It was drifting into nearby fields, damaging crops that didn't have Monsanto's new genes. Reports of this came in from Mississippi to Minnesota, three million acres in all.
BOB SCOTT: It became impossible. The calls were coming in, three and four a day. Sometimes eight or 12 a day.
CHARLES: Bob Scott is a weed expert at the University of Arkansas.
SCOTT: There is no precedent for what we've seen this year.
CHARLES: Now, Monsanto insists it knows what happened - the people doing the spraying didn't follow directions. The company's Scott Partridge says Monsanto checked out more than a thousand cases of dicamba damage.
PARTRIDGE: And in 88 percent of those instances, the label was not followed.
CHARLES: People sprayed dicamba too close to neighboring fields, used the wrong nozzles.
PARTRIDGE: Every one of those is fixable by education.
CHARLES: But I talked to half a dozen weed scientists at universities, and they're pretty sure that's not the whole story. Remember, three million acres of crops, entire fields with curled-up leaves. It didn't seem likely it was all the result of people making mistakes in spraying. So Bob Scott and other scientists carried out their own experiments.
SCOTT: So what we're actually seeing on some of these beans are some of the misshapen seed pods that you get.
CHARLES: Scott's showing me a field of soybeans. The damage here definitely did not come from mistakes in spraying.
SCOTT: We did not spray this plot.
CHARLES: The dicamba that damaged these plants came from trays of soil that had been sprayed far away from here and then placed between the rows. It evaporated from the trays and injured the plants. That's not supposed to happen. This formulation of dicamba is not supposed to evaporate. But in these test plots it did happen, a lot.
SCOTT: A lot of people were extremely disappointed when they saw the plots. A lot of people didn't want to see what they were seeing and were in disbelief.
CHARLES: Because if dicamba evaporates and spreads, it can't really be controlled.
SCOTT: If it were any other product, I feel like it would just be pulled off the market and we'd be done with it.
CHARLES: But dicamba's not just any product. There's big money behind it. Monsanto, seed dealers, farmers who are struggling with weed problems, they all want these dicamba-tolerant crops. The small band of university scientists who are contradicting Monsanto's explanation of the problem are standing in the way of an economic juggernaut. And they're feeling the heat. In Arkansas, Monsanto told state regulators to disregard information from one of the University of Arkansas's weed researchers because he'd recommended the farmers use a non-dicamba alternative from a rival company. Kevin Bradley at the University of Missouri came up with that estimate of dicamba damage on three million acres. He says executives from Monsanto have been calling his supervisors.
KEVIN BRADLEY: What the exact nature of all of those calls were, I'm not real sure, but I'm pretty sure that it has something to do with not being happy with what I was saying.
CHARLES: I contacted three deans at the University of Missouri asking for details about the calls. A university spokesman said they were too busy to respond. Monsanto's Scott Partridge, for his part, says the company respects Bradley's work. Bradley says it hits him even harder when locals tell him he's hurting farmers.
BRADLEY: That's a hard one to take. We chose these jobs to help the farmers in our states. You know, there's not a whole lot of glory in these positions or some kind of major financial incentive.
CHARLES: For now Monsanto's explanation for this summer's dicamba damage is carrying the day. The Environmental Protection Agency says farmers can use dicamba again next year, with a few additional restrictions on who can spray it and when. Monsanto expects sales of dicamba-tolerant seeds to double. Dan Charles, NPR News.