WSU researcher: Use of herbicide rises in US farms

That never sat well with Charles Benbrook, a researcher at Washington State University. So he decided to check the facts.

"I got into this originally to try to keep the biotech industry honest," he said.

According to his peer-reviewed paper published recently in the journal Environmental Sciences Europe, it's quite clear: Genetically-modified crops have led to a significant increase in the use of herbicides.

At a time when as much as 90 percent of the U.S. corn, soybeans and cotton in production are genetically engineered, the use of herbicides will continue to increase, leading to the introduction of more herbicide-resistant weeds, he said. This can lead to all sorts of troubles down the road for farmers.

Karen Batra, a spokeswoman for the Biotechnology Industry Organization, which represents Monsanto, said other studies have come to different conclusions. Moreover, she said, genetically-modified crops have done more environmental good than harm.

For years, large-scale farmers have relied on chemicals to control pests, including herbicides that kill weeds and insecticides that kill bugs. But in the 1990s, companies like Monsanto introduced seeds that were genetically engineered to deal with pests in new ways.

Some crops were spliced with a gene that was resistant to the Monsanto weedkiller Roundup, generically called glyphosate. Farmers could spray their "Roundup Ready" crops with glyphosate knowing the chemical would kill the weeds but not the crops. They also altered crops to resist bugs.

Some consumers are uncomfortable with genetically-engineered food, concerned it may have unforeseen effects on human health. Benbrook was more interested in the weeds.

Examining data from regular U.S. Department of Agriculture (USDA) surveys of corn, cotton and soy production, Benbrook said he learned Monsanto was right — initially.

Herbicide and insecticide use decreased for the first few years after these crops were introduced, in 1996. Insecticide use is still lower than it was, although it is creeping upward.

Herbicide application, however, then began to steadily increase. Benbrook calculates 527 million additional pounds of herbicides were used on these genetically-engineered crops between 1996 and 2011. The increase far outstrips the much smaller decrease in insecticide usage. All told, an additional 404 million pounds of the chemicals were used, a 7 percent increase, he said.