There was a moment, about 20 years ago, when farmers thought that they’d finally defeated weeds forever.
Biotech companies had given them a new weapon: genetically engineered crops that could tolerate doses of the herbicide glyphosate, also known by its trade name, Roundup. Farmers could spray this chemical right over their crops, eliminate the weeds, and the crops were fine.
Stanley Culpepper remembers that moment. He’d left his family’s farm to study weed science at North Carolina State University. “I was trained by some really, really amazing people,” he says, “and I was even trained that there would never be a weed that was resistant to Roundup.”
These scientists believed that plants couldn’t become immune to Roundup because it required too big of a change in a plant’s biology.
In 2005, though, Culpepper reported that he’d found some weeds that Roundup could not kill. They were growing in a field in Georgia. And this was not just any weed. It was a kind of monster weed called Palmer amaranth, or pigweed.