The state on Monday dramatically scaled back the size of a quarantine area created to stop the spread of the European grapevine moth in Sonoma County, marking the latest victory in the wine industry's battle against the pest.

A state and federal quarantine area will remain for a three-mile-wide swath of land in Sonoma County along the border of Napa County, where the moth was first discovered more than three years ago.

The quarantine previously took in 46,500 acres of land in Sonoma County, said Tony Linegar, the county's agricultural commissioner. He put early estimates of the revised area at about 5,600 acres.

Napa County will remain completely under quarantine, as will a small portion of Solano County. But quarantines were lifted Monday for all of Santa Clara, Nevada and Santa Cruz counties.

Last spring, officials lifted quarantines for Mendocino and three Central Valley counties.

The grapevine moth was first found in Sonoma County in March 2010, six months after growers discovered the insects had ruined a crop at an Oakville vineyard in Napa County. The discovery of more moths eventually expanded the quarantine area from Napa County to Sebastopol in the west and Healdsburg in the north.

Nine moths were trapped in Sonoma County in 2011, Linegar said. But none were found last year, which officials considered a victory.

"A lot of the credit really goes to the growers, who sprayed when we asked them to spray," Linegar said. "Really, the battle's won in the vineyards."

The end of the quarantine will mean less spraying of vineyards and fewer rules regarding grape shipments to other counties or states.

"It just makes things a little easier for people," said Nick Frey, president of the Sonoma County Wine Grape Commission.

The county will continue setting out moth traps in vineyards for years, Linegar predicted. Growers must continue to make sure all equipment coming from the Napa quarantine area is free of moths and larvae. And Sonoma County wineries must continue to properly dispose of any plant material coming from Napa.

State officials on Monday said 317,000 acres of land have been removed from quarantine and 439,000 acres remain under it.

"By removing these counties from quarantine, we are a step closer to eliminating European grapevine moth in California," said state Agriculture Secretary Karen Ross.