Addressing Roundup-Resistant Weeds

Weed ( scientist David Mortensen caused quite a stir last summer when he told a group of politicians that the government should restrict the use of herbicide-resistant crops and impose a tax on genetically engineered seeds to fund research and education programs for farmers.

Testifying before the Domestic Policy Subcommittee of the House Oversight and Government Reform Committee in July, the professor of weed ecology explained how the use of crops that are genetically engineered to resist glyphosate—the active ingredient in the herbicide Roundup—has caused certain weed plants to also evolve resistance to glyphosate.

According to Mortensen, 19 weedy plant species have already evolved resistance to glyphosate since glyphosate-resistant crops were introduced in 1995, and these plants have infested up to 11.4 million acres in the United States. “In addition,” he said, “forestalling and controlling herbicide-resistant weeds is estimated to cost farmers almost $1 billion each year.”

Mortensen expressed concern that biotechnology companies are trying to solve the problem by engineering new crop varieties that will be resistant to more than one herbicide, including herbicides that are more dangerous than Roundup. “The use of crops that are resistant to multiple herbicides could result in a 70 percent increase in the amount of herbicides that are used,” he said, “and even those products eventually will run into resistance problems if farmers aren’t careful.”