A combine harvests wheat along the Oregon-Washington border. (AP Photo/Jeff Horner.) A combine harvests wheat along the Oregon-Washington border. (Jeff Horner/Associated Press)

A rural county in southern Oregon overwhelmingly decided to ban genetically engineered crops Tuesday, beating out an expensive opposition campaign that attracted nearly $1 million in spending from some of the region’s biggest agribusiness groups.

Two-thirds of voters approved the ban, which gained national attention as it pitted small organic growers against large-scale farm operations in Oregon’s burgeoning agriculture sector. The county counts just 120,000 registered voters, but it was flooded by more than $1.3 million in political spending — more than $100 per registered voter — leading up to this week’s vote.

The fight over GMOs began in Jackson County two years ago, when residents learned that a Swiss company was planting sugar beet seeds that had been bioengineered to resist weed killer. Fearing that their own crops could be exposed through cross-pollination, a group of local growers began trying to ban the cultivation of all genetically modified crops in the county.

Agriculture groups have attacked the proposal as a burden on farmers who rely on the widespread practice to stay in business, arguing that research has not shown GMOs to have negative effects.

“Regrettably ideology defeated sound science and common sense in Jackson County,” Barry Bushue, president of the Oregon Farm Bureau, said in a release.

But the leader of an Oregon-based group called Friends of Family Farmers argued that the ban is necessary to protect consumers and counteract the lack of government oversight in agriculture.

“This is really an issue where local family farmers don’t believe the state has done a good job protecting their interests,” Ivan Maluski, the group’s director, told the Oregonian. “This local effort is important because it’s a way for local growers to protect their property rights from genetically engineered pollen contaminating their seed crops.”

About 20 years after genetically engineered food products first appeared in the U.S. market, they make up more than 90 percent of sugar, soy, cotton and corn crops, according to a report last month by the Council for Agricultural Science and Technology.

Jackson County’s ban is unlikely to spread across the state, as Oregon banned local governments from regulating the use of bioengineered crops last fall. (Jackson County is exempt because its ballot initiative had already been approved when the law went into effect.)

Oregon could see another GMO battle in November, as food activists began collecting signatures this week for a food-labeling ballot initiative, which is also gaining steam in Arizona and Colorado.

Those states would follow Vermont, Maine and Connecticut, which have approved GMO food-labeling initiatives.