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Farmers Face Tough Choice On Ways To Fight New Strains Of Weeds

Mar 7, 2012
Originally published on March 7, 2012 5:23 am

OK, so this story is about weeds and weedkillers, neither of which is ever the hero of a story, but stay with me for a second: It's also about plants with superpowers.

Unless you grow cotton, corn or soybeans for a living, it's hard to appreciate just how amazing and wonderful it seemed, 15 years ago, when Roundup-tolerant crops hit the market. I've seen crusty farmers turn giddy just talking about it.

All they had to do was spray the herbicide Roundup over their fields and everything died — except their remarkable new crops, with their laboratory-inserted genes that made them resistant to that weedkiller.

Alas, the giddiness faded. In more and more places across the country, farmers now are struggling to deal with weeds that their favorite weedkiller won't kill anymore. The weeds, too, have evolved Roundup-resistance superpowers.

Now, a hot debate has erupted over what farmers should do next. Should they adopt a new generation of genetically engineered, herbicide-resistant crops? Or turn away from chemical herbicides altogether? (A national summit on this issue is planned for May, in Washington, D.C.)

To get a closer look at this debate, I went to south Georgia, where farmers are fighting one of the most irrepressible of the new superweeds. It's called Palmer amaranth, known to the locals here as pigweed.

"It started just north of us," recalls Randy Bryan, who grows cotton in Irwin County. "And then all of a sudden, it was all over south Georgia. We had it everywhere."

Palmer amaranth can grow 3 inches a day. A single plant can release close to a million seeds. It's a bully; if you let it grow beside cotton seedlings, the poor cotton doesn't stand a chance.

Many farmers still spray glyphosate, but then they have to hire people to go in to the fields and pull pigweed by hand, or chop it down with hoes.

"I have a brother-in-law who told me he spends $120 an acre on hand labor," says Van Grantham, a cotton grower in Coffee County. That's about four times what farmers spent to control weeds five years ago.

Cotton prices are high right now, so nobody is abandoning the crop altogether, but if prices returned to normal levels, the cost of containing Palmer amaranth could make cotton unprofitable.

Farmers are looking for alternate solutions, and in Georgia, they turn to Stanley Culpepper. He's a weed scientist at the University of Georgia and the state's expert on cotton weeds. This time of year, he spends his days driving from county to county, delivering talks to cotton farmers.

Culpepper grew up in North Carolina, and comes from a long line of farmers. He talks to his cotton growers like a football coach giving his players some tough love.

"We all agree: There can be no glyphosate-resistant Palmer amaranth at planting, right? We've crossed the bridge. We know there has to be no Palmer at planting or you won't pick your crop. If you do pick your crop, it won't be economically sustainable," he told a hall filled with about 70 farmers in Coffee County.

And you can't just take your time about it, either. "You go out and look at the field and you say, 'Ahh, I got me a few more days.' And what happens when you say, 'I got a few more days' — those pigweeds come up and they're 4 to 5 inches tall when you get there, and you can't kill 'em."

You're going to have to spray a lot of different chemicals to overwhelm the enemy, Culpepper tells the farmers. Some will kill your cotton if you aren't careful.

Then, Culpepper puts up a new slide. It's a picture of a field that's covered with a layer of rye, flat on the ground.

This residue works as well as any weedkiller, he tells the cotton growers. Pigweed just despises it. So the system would be: Grow a crop of rye, then roll it flat to keep weeds from growing. But leave some narrow gaps in the rye, and that's where you plant your rows of cotton.

Culpepper explains that he's still working out some kinks in this technique. But in just a few years, he says, it could be a big part of the pigweed solution.

"If we can work it out, this is the most sustainable program that we as cotton growers could do, bar none, for resistance management and Palmer amaranth control," he says.

This is Culpepper's recipe for surviving in a world of weeds that could become resistant to your most popular herbicides: Do lots of different things to fight the weeds. Some of them involve chemicals, some don't. Some will mean more work. But the work is worth it.

But Culpepper's is not the only recipe in the room. The one that may prove to be really tempting for farmers is one offered by three other non-farmers in the room this evening. They represent three big cotton seed companies: Dow AgroSciences, Monsanto and Bayer CropScience.

Those companies are selling — or plan to sell, within a few years — crops that have been engineered to tolerate other herbicides that will kill pigweed. Farmers will be able to spray those herbicides — long-established chemicals called 2,4-D and dicamba — right over their crops, just as they do today with glyphosate.

Some environmentalists are angry about these new products. The Natural Resources Defense Council, for instance, says 2,4-D is dangerous and ought to be banned.

And David Mortensen, a weed ecologist at Penn State University, predicts that weeds will evolve resistance to these herbicides, too. He says it's a kind of treadmill, where farmers constantly need new weedkillers.

"When one herbicide fails, you add a second herbicide, and then a third herbicide to the package. And I am convinced that this is not a sustainable path forward," he says.

The University of Georgia's Culpepper, meanwhile, stands somewhere in the middle of this argument.

"Let's be clear: I want all the new technology that's economically and environmentally friendly for our growers that we can get," he says.

The key is not to misuse them; not to rely just on one or two of them, because then the weeds will adapt.

Culpepper thinks his farmers have learned that lesson, and what happened with Roundup doesn't need to happen again.

Copyright 2018 NPR. To see more, visit http://www.npr.org/.

STEVE INSKEEP, HOST:

You can trace the following pattern in every kind of conflict: Somebody makes a radical improvement in offensive weaponry and then someone else improves the defense. It's true in war. It's true in football. And it's definitely true in the epic battle between farmers and weeds.

For the last decade or so, the weeds have been losing badly. Farmers have been winning with genetically engineered crops and the weed killer Roundup. Now some weeds are becoming Roundup resistant and there's a big argument about what farmers should try next. Here's NPR's Dan Charles.

DAN CHARLES, BYLINE: The combination of Roundup and so-called Roundup-ready crops was so amazing when it came on the market 15 years ago, it made grown men giddy. Roundup killed everything except for your cotton, soybeans, or corn. Those crops were genetically engineered to withstand the herbicide. It changed American agriculture. It made controlling weeds so simple, farmers went out and rented more land. Farms got bigger.

And then the magic started to wear off. At different places in different parts of the country, farmers realized that some weeds were not dying. In Georgia, it was a plant called Palmer amaranth, or pigweed.

RANDY BRYAN: It started just north of us here, three or four counties up.

CHARLES: Randy Bryan grows cotton in Irwin County, Georgia. At first he thought it was just somebody else's problem.

BRYAN: And then all of the sudden it was all over South Georgia. We had it everywhere.

CHARLES: This strain of Palmer Amaranth has a genetic mutation that makes it resistant to glyphosate, the weed-killing chemical in Roundup. Pigweed can grow three inches a day. A single plant can release close to a million seeds. This is a bully. Let it sprout beside cotton seedlings and the poor cotton won't stand a chance.

Farmers in Georgia like Vann Grantham are hiring people to go into cotton fields and pull the pigweed by hand.

VANN GRANTHAM: I've got a brother-in-law that told this year he spend $120 an acre on hand labor.

CHARLES: That's about four times what weed control used to cost. Farmers are looking for solutions, and the man they turn to is Stanley Culpepper. He's a weed scientist at the University of Georgia and the state's expert on cotton weeds. This time of year he spends his days driving from county to county delivering talks to cotton farmers.

STANLEY CULPEPPER: We all agree that there can be no glyphosate-resistant palmer amaranth up a planting, right? We've crossed that bridge. We know it has to be no palmer at planting, or you probably won't pick your crop. If you do pick your crop, you won't be economically sustainable.

CHARLES: Culpepper grew up in North Carolina and comes from a long line of farmers. He talks to these cotton growers like a football coach giving his players some tough love. The days of easy weed killing are over, he tells them. You can't be lazy anymore.

CULPEPPER: You go out and look at the fields, you say, oh, I've got me a few more days. And what happens when you say I'm going to wait a few days, those pigweeds come up and they're four or five inches when you get there and you can't kill them.

CHARLES: You'll have to spray a whole bunch of different chemicals to overwhelm the enemy, Culpepper says. Some will kill your cotton if you aren't careful.

Now, here, he says, here's something completely different. He puts up a new slide, a picture of a field that's covered with a layer of rye lying flat on the ground. This residue works as well as any weed killer, he says. Pigweed just hates it.

So we can grow this cover crop of rye and we leave some narrow gaps in it. That's where we plant our rows of cotton. I'm still working out a few kinks in this technique, he says. But in just a few years, I think this is something you should try.

CULPEPPER: If we can figure this out, this program is the most sustainable program we as cotton people could do, no question, bar none, for resistance management and for Palmer control.

CHARLES: So here's Stanley Culpepper's recipe for surviving in a world of Roundup-resistant weeds: Do lots of different things. Some of them involve chemicals, some don't. Some will mean more work.

But there are other recipes out there. And the one that may be really tempting for farmers is more genetically engineered crops. At this same meeting there are representatives from three big cotton seed companies: Dow, Monsanto and Bayer.

Those companies are selling, or plan to sell very soon, crops that have been engineered to tolerate other herbicides that will kill pigweed. So farmers may be able to spray those herbicides, old ones called 2-4-D and Dicamba, right over their crops.

Some environmentalists are angry about these new products. The Natural Resources Defense Council, for instance, says 2-4-D is dangerous and ought to be banned. And David Mortenson, a weed ecologist at Penn State, predicts that weeds will evolve resistance to these herbicides too. It's a kind of treadmill, he says, where farmers constantly need new weed killers.

DAVID MORTENSON: When one herbicide fails, then we add a second herbicide, and you turn it for a while, and then add a third herbicide to that package. And I am convinced that that is not a sustainable path forward.

CHARLES: Stanley Culpepper, meanwhile, stands somewhere in the middle of this argument.

CULPEPPER: Let's be clear. I want all the new technology that's economically and environmentally friendly for our growers that we can get.

CHARLES: But we can't misuse the technologies, he says. We can't overuse just one or two of them. He thinks his farmers have learned that lesson and what happened with Roundup will not happen again.

Dan Charles, NPR News. Transcript provided by NPR, Copyright NPR.