A decision by the U.S. Department of Agriculture this week to allow the unrestricted farming of genetically modified alfalfa should give a big boost to Land O' Lakes' alfalfa seed operation.

Forage Genetics, a subsidiary of Arden Hills-based Land O'Lakes, co-developed a pioneering genetically modified alfalfa seed with St. Louis-based Monsanto Co. The seeds are bred to be resistant to Monsanto's Roundup herbicide, boosting crop yields and quality.

But genetically modified seeds of all kinds have drawn stiff opposition from organic farming groups and environmentalists. They claim such seeds can lead to the evolution of herbicide-resistant weeds -- "superweeds" -- and cause contamination of conventional and organic crops through inadvertent cross-pollination.

USDA Secretary Tom Vilsack on Thursday gave the green light to genetically modified alfalfa, meaning that farmers can plant the stuff during this spring's growing season -- unless opponents mount another successful court challenge to stop the seeds' spread. Vilsack's announcement came after the USDA completed an environmental impact statement deeming genetically modified alfalfa safe.

Alfalfa is the nation's fourth-largest field crop, and it's a key component of livestock feed, particularly for dairy cows. Land O' Lakes, one of the nation's largest farmer-owned co-ops, has been an alfalfa seed breeder and producer for decades. After Monsanto introduced its Roundup-ready seeds for corn and other crops in the mid-1990s, Forage Genetics began collaborating with the agribusiness giant to bring the technology to alfalfa.

"As a breeding company, we always pride ourselves on being on the cutting edge of new technology," said Mark McCaslin, Forage Genetics president. So, Forage worked to install Monsanto's Roundup gene into alfalfa seed, he said.

The growth potential for the Monsanto/Forage seeds is huge. Currently, only about 1 percent of U.S. alfalfa production comes from genetically modified seeds, McCaslin said. "We think within three to five years, there's a potential for half of the alfalfa crop in the U.S. to be Roundup ready," he said.

Keith Poier, project manager for the farm co-op Minnesota Valley Alfalfa Producers, said many farmers will likely welcome the USDA's decision. "It's always good to have tools in the toolbox, and this is another tool for us. There are issues that go along with it, but that's up to individual farmers to decide."

The Organic Trade Association said the USDA's decision will make it increasingly difficult to grow organic crops. "The organic standards prohibit the use of genetic engineering ... yet GE crops continue to proliferate unchecked," the trade group's chief executive, Christine Bushway, said in a statement.

Mike Hughlett • 612-673-7003