SANTA ROSA -- A proposed ban on planting or cultivating genetically altered crops was rejected by Sonoma County voters Tuesday night.

With 68 percent of precincts reporting, Measure M lost 57 to 43 percent in one of the county's most expensive ballot fights ever.

Supporters and opponents of the proposed 10-year ban spent a combined $850,000. Only three counties in the nation -- all in California -- ban genetically altered crops.

Sonoma County anti-biotechnology crusaders placed Measure M on the ballot earlier this year, hoping to join neighboring Mendocino County in officially banning biotechnology from its farms, spread out over a region best known for pastoral vineyards and lush orchards.

Mendocino County voters in March 2004 were the first in the nation to enact such a ban, overwhelmingly approving the measure despite a well-funded counter campaign from the biotechnology industry.

In November 2004, voters in Marin County, a mostly suburban region just across the Golden Gate Bridge from San Francisco, enacted their own ban on genetically modified crops, while voters in Humboldt, Butte and San Luis Obispo counties voted down proposed biotechnology bans.

The Board of Supervisors in tiny Trinity County also passed a similar ban.

Opponents of genetically modified crops have lobbied for outright bans in Hawaii and Vermont, but California remains the only state in the nation where voters have enacted such bans.

The bans are largely symbolic because few -- if any -- genetically engineered crops were grown in those counties. The same is true for Sonoma County, where the winemaking grape is king. No genetically engineered grapes are commercially available.