MILWAUKEE - The federal government on Friday proposed eliminating restrictions on the use of corn and soybean seeds that are genetically engineered to resist a common weed killer, a move welcomed by many farmers but feared by scientists and environmentalists who worry it could invite growers to use more chemicals.
The herbicide known as 2,4-D has had limited use in corn and soybean farming because it becomes toxic to the plants early in their growth. The new seeds would allow farmers to use the weed killer throughout the plants' lives.
Farmers have been eager for a new generation of herbicide-resistant seeds because of the prevalence of weeds that have become immune to Monsanto's Roundup. But skeptics are concerned that use of the new seeds and 2,4-D will only lead to similar problems as weeds acquire resistance to that chemical too.
In this undated photo released by Dow AgroSciences, soybean plants that were grown from soybean seeds genetically engineered to resist a common weed killer are seen.
"It's just so clear. You can see that you have this pesticide treadmill effect," said Bill Freese, a chemist with the Washington, D.C.-based Center For Food Safety, which promotes organic agriculture.
Most corn and soybeans grown in the U.S. are already genetically engineered, largely to resist Roundup, which was introduced in 1976. Before that, most farmers tilled their fields prior to planting, flipping the soil over and burying the weeds to kill them. The technique also exposed tilled earth to the air, creating problems with erosion and runoff.
Herbicide-resistant seeds permitted most farmers to stop tilling because they could spray fields after their plants emerged, killing the weeds but leaving crops unharmed.
The new generation of plants "allowed us to do a better job of controlling the weeds, and therefore, we've been able to do a better job of preserving the soil, which is our primary natural resource," said Ron Moore, who grows 2,000 acres of corn and soybeans with his brother in western Illinois.
The U.S. Department of Agriculture's plant-inspection agency concluded that the greatest risk from the new seeds developed by Dow AgroSciences was increased use of 2,4-D, which could hasten the evolution of weeds resistant to it.
But, the agency said, resistance could develop anyway because 2,4-D is the third most-used weed-killer in the nation.
Freese and other advocates also raised concerns about possible health risks from increased use of 2,4-D and the chemical's tendency to drift beyond the area where it is sprayed, threatening neighboring crops and wild plants.
Dow AgroSciences has attempted to address that by developing a new version of 2,4-D and new equipment to use with it, company spokesman Garry Hamlin said.
The seeds and new 2,4-D have been approved in Canada but not yet sold there. The company has targeted their release in the U.S. for 2015, pending approval by various federal agencies. In anticipation of that, it has received import approval from seven nations and has applications pending in about six others to allow farmers who use the seeds sold under the Enlist brand to export their crops.
Some nations, particularly in Europe, have been resistant to genetically engineered crops, and consumer concerns have created a market for organic and other foods made without genetically modified ingredients. Minneapolis-based General Mills announced Thursday that it had switched the sugar and cornstarch in original Cheerios to make that product GMO-free.
For now, Dow AgroSciences' seeds can only be used in tightly controlled trials.