美国国家公共电台 NPR Rogue Weedkiller Vapors Are Threatening Soybean Science（在线收听）

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There is a weed killer that American farmers spray on millions of acres. It's hard to control, and its fumes have drifted across the landscape, damaging other crops and wild vegetation. Now the chemical is becoming a threat to scientific research on one of the world's most important crops - soybeans. NPR's Dan Charles has the story.

DAN CHARLES, BYLINE: Professor Pengyin Chen at the University of Missouri has devoted his life to soybeans - breeding new varieties of it.

So you've been breeding soybeans for how long?

PENGYIN CHEN: Twenty-eight years. If you're counting my student - graduate school, it's more than 30 years now.

CHARLES: He takes different soybean plants, cross-pollinates them, reshuffling the genes the way you'd reshuffle and deal cards, looking for the genetic version of a lucky hand.

CHEN: We do the magic combination.

CHARLES: He does it here on 16,000 or so small plots of soybeans at the Fisher Delta Research Center in the southeastern corner of Missouri.

CHEN: This is the first field we planted this year.

CHARLES: But something is wrong with the soybeans out here.

CHEN: You see how small they are? - the canopy.

CHARLES: The leaves ought to be wide and flat. Instead, they're curled into cups. Also, instead of growing straight up, the plants are putting out fragile, little side branches.

CHEN: This plant is not supposed to have a branch there. No.

CHARLES: It's kind of being deformed.

CHEN: Yes, somewhat. Yeah.

CHARLES: It's pretty clear what's going on here, actually. Chen's been seeing this kind of damage for three years now, ever since farmers all around this research station and across the country started planting a different kind of soybeans. These soybeans are genetically modified to tolerate a herbicide called dicamba. So farmers can spray dicamba in their fields, and it kills the weeds. But the dicamba-tolerant soybeans are fine. Dicamba's arrival is provoking two different reactions.

CHEN: Love it or hate it.

CHARLES: Farmers who use dicamba love it because it works. The neighbors, though - they've got a problem. All over the country, dicamba's been evaporating and floating away, damaging vegetation that doesn't have those special dicamba-tolerance genes, especially soybeans. They're incredibly sensitive to dicamba. Now, most farmers have now switched over to dicamba-tolerant soybeans. Their fields are safe. Chen can't switch, though, because he's supposed to produce knowledge not more soybeans. He's a so-called public soybean breeder - a non-commercial alternative to the big seed companies. The soybeans he's studying out here are not dicamba-tolerant, so they are suffering.

CHEN: It was very discouraging and very hurtful. I mean, as a scientist, you see all the research being affected. And we were not able to do a scientific analysis of the data.

CHARLES: Public breeders like Chen are like custodians of genetic diversity for the world's most important crops. They study obscure kinds of soybeans that private seed companies ignore, searching for hidden genetic treasures - genes that can make soybeans more resilient and productive. His biggest worry is that dicamba's making it impossible to carry out public research on soybeans here and maybe other places too.

CHEN: If you kill all the public research programs, who is going to study the disease resistance or stress tolerance? So those efforts are going to be gone.

CHARLES: Soybean researchers in other places are having problems. They're reporting damage at the University of Nebraska, Kansas State and at the University of Arkansas. I visited a research farm in the town of Keiser in northeast Arkansas. And station manager Mike Duren showed me soybeans with classic dicamba symptoms.

MIKE DUREN: The very tip of the leaf itself has a distinct curled-up point to it.

CHARLES: Do you think - walking around this farm, you said 700 acres. Of the acres that are in soybeans, how many of them do you think would show these kinds of symptoms?

DUREN: A hundred percent.

CHARLES: Hundred percent - every single one.

DUREN: Yes.

CHARLES: The company Bayer, which created dicamba-tolerant soybeans, says dicamba does not cause problems when people use it properly, following all the rules. In an email to NPR, the company wrote that it's aware of the damage at Chen's research plots. It suggested that perhaps it came from nearby farmers spraying an older, unauthorized version of the chemical. Researchers at universities in other places like Tennessee, Minnesota and North Carolina say their soybean experiments are doing fine. But some of them also say they're worried because farmers are planting more dicamba-tolerant soybeans every year, spraying more of this chemical and increasing the chances it'll do more damage.

Dan Charles, NPR News.