(NBBJ) - While the 2012 winegrape harvest in Sonoma County appears to have been among the county’s largest ever, the market for grapes continues to be active early in the 2013 buying cycle, yet rising costs and uncertain ability to increase retail prices is crushing wine producer margins, according to industry supply and finance experts at a major seminar today. “It’s been a turbulent two to three years in the wine industry,” said Glenn Proctor, partner of Ciatti Co., to an audience of several hundred at Sonoma County Winegrape Commission’s Dollars & Sense Seminar in Santa Rosa.