Trojan Corn, super weeds and butterflies: GMO crops raise concern

Updated: Aug 27

Carolyn Lochhead

April 30, 2012

Washington -- Biotechnology's promise to feed the world did not anticipate "Trojan corn," "super weeds" and the disappearance of monarch butterflies.

But in the Midwest and South - blanketed by more than 170 million acres of genetically engineered corn, soybeans and cotton - an experiment begun in 1996 with approval of the first commercial genetically modified organisms is producing questionable results.

Those results include vast increases in herbicide use that have created impervious weeds now infesting millions of acres of cropland, while decimating other plants, such as milkweeds that sustain the monarch butterflies. Food manufacturers are worried that a new corn made for ethanol could damage an array of packaged food on supermarket shelves.

Some farm groups have joined environmentalists in an attempt to slow down approvals of genetically modified organisms, or GMOs, as a newly engineered corn, resistant to another potent herbicide, stands on the brink of approval.

In this Oct. 31, 2005, file photo, a harvester works through a field of genetically modified corn near Santa Rosa, Calif. So-called Bt corn, genetically engineered to make its own insecticide, may be losing its distinctive ability to kill pests _ a possible result of careless farming practices that could give rise to resistant bugs and threaten the future of one of the nation's most widely planted crops. (AP Photo/Rich Pedroncelli, File)

Vote on labels

In November, Californians are likely to vote on a ballot initiative to require labeling of genetically engineered foods, which backers of the measure say would give consumers a voice over the technology that they lack now.

The initiative is part of a nationwide drive to thwart the Obamaadministration's expected clearance of a new genetically modified corn that could flood the nation's cornfields with 2,4-D, a 1940s-era herbicide used mainly on lawns and golf courses to kill broadleaf weeds.

More than a million people have signed a petition to the Food and Drug Administration to require labeling of genetically engineered food. That is "more than twice the number who have ever commented on any food petition in the history of the FDA," said Gary Hirshberg, chairman of organic yogurt maker Stonyfield and a leader of the "Just Label It" campaign.

The stakes on labeling such foods are huge. The crops are so widespread that an estimated 70 percent of U.S. processed foods contain engineered genes. The U.S. Department of Agriculture has approved more than 80 genetically engineered crops while denying none.

Mushy corn feared

Organic farmers have long fought the spread of such crops, fearing pollen contamination of their fields. Environmentalists have warned of long-term health and environmental effects.

Now, even biotech supporters fear collateral damage. Vegetable growers warn of plant-killing fogs that they say will accompany the new genetically modified corn. Snack and cereal makers fear that a new corn engineered for ethanol may escape its fields and turn their corn chips and breakfast cereals to mush.

Midwest fruit and vegetable growers this month petitioned the Department of Agriculture to block approval of the 2,4-D-tolerant corn, called Enlist and made by Dow AgroSciences. Similar crops, including a soybean engineered by Monsanto to tolerate dicamba, a similar herbicide, wait in the regulatory pipeline.

Current forms of the herbicides are prone to vaporization and can travel miles from their target, falling back to Earth with rain or fog. Vegetable growers predict the new corn will unleash rampant use of 2,4-D and dicamba, potentially damaging every broadleaf plant in their path other than those engineered to tolerate them.

"Suddenly we are looking at a very dangerous system, because more dangerous herbicides in America are going to be far more extensively used," said John Bode, executive director of the Save Our Crops Coalition, a group working to protect nontargeted plants from herbicides. It has asked the USDA to conduct a full environmental impact analysis.

Preliminary OK

The USDA's Animal Plant Health Inspection Service, which has chief regulatory authority over genetically engineered crops, has given a preliminary recommendation that the new corn be fully commercialized without restriction.

Michael Gregoire, who heads the agency, said any genetically modified crop that does not meet the definition of a "plant pest," which attacks other plants, falls outside the agency's authority.

"Once we determine that a genetically engineered plant is not a plant pest based on a risk assessment, our jurisdiction and our authority to continue to regulate that ends," Gregoire said.

The Environmental Protection Agency has found that 2,4-D poses "a reasonable certainty of no harm," but will evaluate the effects of using it with genetically modified crops later in the growing season after plants have leafed out and temperatures are higher.

If approved, the new corn could be planted as early as next spring. Charles Benbrook - a former head of the agriculture board of the National Academy of Sciences who is chief scientist of the Organic Center, a Colorado group that researches the environmental benefits of organic farming - projects a 1,435 percent increase in the amount of 2,4-D applied, or 283 million pounds, within seven years.

Hardier weeds evolve

Corn and soybean farmers are clamoring for the new genetically engineered crops because those now in use have spawned an infestation of "super weeds" now covering at least 13 million acres in 26 states. The crops are engineered to tolerate glyphosate, commonly known by its Monsanto trademark Roundup. They greatly simplified weed control by allowing farmers to apply the herbicide to their fields yet leave their corn and soybeans unharmed.

The crops led to a 400-million-pound net increase in herbicide applications throughout corn, soybean and cotton growing regions, according to Benbrook.

The resulting overexposure to glyphosate encouraged the evolution of hardier weeds that can tolerate it. Dave Mortensen, a weed ecologist at Pennsylvania State University, said the number of "super weed" species grew from one in 1996, when genetically modified crops were introduced, to 22 today.

Scientists warn that the next generation of genetically modified crops will likewise encourage overuse of 2,4-D and dicamba, creating still hardier weeds that can tolerate virtually every herbicide on the market.

"It's like pouring gasoline on a fire," Benbrook said.

"We're talking about a lot of pesticide," Mortensen said. "Whether it moves as a vapor or physical drift or surface water runoff or comes down in rainwater, the more of something you use, the greater the likelihood you will see it appearing in places where you did not apply it."

Mortensen worries that 2,4-D and dicamba will damage not just fruit and vegetable crops, but also wild plants on field edges that harbor pollinators. In the Midwest, where there is little plant diversity, "those field edges become critically important reservoirs for hosting beneficial insects," Mortensen said.

Butterflies in decline

Last month, scientists definitively tied heavy use of glyphosate to an 81 pe