LOS ANGELES (Reuters) - Mendocino County's reputation as a marijuana haven of California may be going up in smoke.

Voters on Tuesday leaned toward repealing a law allowing home marijuana growing, according to preliminary results of a ballot measure vote released on Wednesday.

Critics say a cottage industry had grown out of control.

California in 1996 voted to allow possession and cultivation by residents of marijuana for medical purposes, despite federal law which declares it illegal.

Mendocino, a rural county north San Francisco, in 2000 approved marijuana cultivation for recreational use as well, voting to let residents grow up to 25 marijuana plants, compared with the state limit of six.

With about a third of the vote counted, 52 percent supported repeal, the county clerk said. The tally may not be complete for up to four weeks.

"We thought Ma and Pa growers would be able to grow a little bit," said Dave Bengston, the county's agricultural commissioner, who supported the repeal. "The legalization of marijuana sent a message to organized crime that they could set up shop here, and we got people with automatic weapons growing marijuana in large quantities."

Supporters of local marijuana growing say repeal will hurt legitimate growers, while organized drug cartels will be ignored.

"(The measure) doesn't target the problem of criminals growing," said Laura Hamburg, a spokesperson for a campaign against repeal.

Mendocino Sheriff Thomas Allman said local law enforcement officers seized 334,000 marijuana plants last year.

"We're not trying to break last year's numbers," Allman told Reuters. "We are not targeting legitimate growers, just commercial marijuana."