Jenny Mennenga farms corn and soybean with her husband between Le Roy and Farmer City in central Illinois. This past harvest brought Mennenga’s farm record corn production, though soybean yields were just “fairly average.”
The mediocre soybean yields, she said, were largely related to her farm’s ongoing struggle with “super weeds,” tough weeds that have grown resistant to the herbicides used to kill them.
“The biggest challenge that I’ve got on my farm is glyphosate-tolerant weeds,” Mennenga said. “The two biggest ones that I deal with yearly are waterhemp and marestail.”
Farmers everywhere are fighting a similar battle.
An international survey funded by government, academic and industry groups identified more than 400 different herbicide-resistant weeds globally. In addition to water hemp and marestail, Palmer Amaranth, nightshade, prickly lettuce and clover are all prominent weeds that have gained resistance to herbicides.
And controlling those weeds can be costly.
Mennenga said she spent $40 an acre last year on control efforts for the weed waterhemp alone.
“Controlling weeds in a soybean crop or in even a corn crop is not much different than controlling weeds in a lawn,” Mennenga said. “You let one dandelion go in your lawn, and it’s going to populate the rest of your lawn.”
Similar to the weeds on Mennenga’s farm, most super weeds are resistant to glyphosate, the herbicide used with Monsanto’s genetically engineered Roundup Ready crops from the 1990s. To kill the weeds that have grown immune to glyphosate, Monsanto is working on a next generation of genetically engineered seeds designed to also be used with a different, older herbicide formulated from dicamba.
The U.S. Department of Agriculture deregulated two of those next generation varieties – soybean and cotton – in January.
“As a farmer, I am very supportive of the dicamba soybeans,” Mennenga said.
The soybean and cotton will be part of Monsanto’s Roundup Ready Xtend brand projected to go to market in 2016. Before the soybean and cotton can be commercialized, the Environmental Protection Agency must sign off on their related herbicide use.
“For some time now, we have been hearing from farmers across the country that they need new tools to control tough-to-manage and glyphosate-resistant weeds,” said Miriam Paris, Xtend system launch manager for Monsanto. “These weeds can rob farmers’ crops of nutrients, water and sunlight.”
Brian Diers is a professor in the crop sciences department at the University of Illinois. In the future, he said, it is likely companies will continue pumping out genetically engineered crops designed to withstand multiple herbicides.
“What we’re probably going to be seeing in the future is more crops coming out with additional genes that give resistance to other herbicides,” said Diers, who specializes in soybean breeding and genetics.
The ‘super weed’ cycle
Larry McClendon is a fourth-generation cotton grower who farms anywhere from 5,000 to 10,000 acres a year in eastern Arkansas. He voiced his support for the recently deregulated Monsanto cotton during a USDA public meeting in September.
“As a farmer, I can say with a lot of confidence that growers need new weed management technologies,” he said, according to transcripts from the meeting.
Document: read the GMO meeting transcripts
Bruce Tiffany is a soybean, corn, sweet corn, cattle and sheep farmer in Minnesota. He, too, expressed support for the Monsanto technology. Under a special permit granted by the Animal and Plant Health Inspection Service, Tiffany is one of the select few U.S. farmers who has been able to grow Monsanto’s dicamba-resistant soybean before commercialization.
“My experience is the weed control system is effective, economical, safe for the operator and environmentally responsible,” Tiffany said, according to transcripts.
But while Mennenga, McClendon, Tiffany and other farmers applaud the new Monsanto soybean and cotton, critics argue the move is shortsighted and will only lead to the further reliance on herbicide.
“One of the biggest problems with these crops is that they completely changed the way we control weeds and the way we use herbicide,” said Doug Gurian-Sherman, a senior scientist for the Center for Food Safety. “They essentially encouraged practices of weed control and overuse of these herbicides that has led to an epidemic of weeds that are resistant to those herbicides.”
If Monsanto’s genetically engineered cotton and soybean became commercially available, farmers would widely replace their old Roundup Ready, glyphosate-tolerant seeds with the new dicamba-tolerant ones, Gurian-Sherman said. As a result, they would begin the same cycle that produced the glyphosate-tolerant weeds originally.
The Center for Food Safety, a national nonprofit and public interest organization, projects that the majority of all cotton and soybean crops would become dicamba-resistant.
Instead of turning to a different herbicide to kill the resilient weeds, Gurian-Sherman said farmers should use alternative methods.
However, according to studies cited in a USDA analysis, those methods would lead to steep financial losses for farmers. If growers decreased herbicide use by shifting to more hand weeding and tillage, U.S. crop production would decline by 20 percent with a $16 billion loss in value.
Researchers estimate weeds cause about 37 percent of the world’s soybean production loss.
And – even if farmers shifted to methods outside of genetically modified crops and herbicides – it’s likely the weeds would still find a way to adapt and continue to bother farmers.
“The problem is that, in any of these kinds of situations, nature is eventually going to win,” Diers said.