After Sonoma County's abundant grape crop is crushed and safely in winery tanks, a lesser known but increasingly important harvest gets under way in Wine Country as farm workers turn from vibrant-hued vineyards to verdant olive groves.

Trading their hooked grape-harvest knives for long wooden sticks, workers in recent weeks have been coaxing the county's 600 acres of olive trees to release what growers say is shaping up to be a bumper crop of flavorful fruit.

"The harvest is really excellent this year," said Deborah Rogers, owner of the Olive Press in Sonoma. "It's abundant, the olives are beautiful and fresh and clean and the oil yields are high, so it's a good year."

That's good news for an industry that has seen some challenging harvests in recent years.

State and federal farm officials estimate the state's olive growers could produce 180,000 tons this year, roughly 2 1/2 times the 2011 harvest of 71,200 tons.

In Sonoma County, which boasts more olive oil producers than any other county in the state, the olive crop remains minuscule compared to the grape industry. In 2011, there were 567 acres of olives in the county, compared to the 60,000 acres of vineyards. The crop was valued at $100,000 versus $350 million for wine grapes.

But the industry is becoming an increasingly important one for the region, blending well with existing food-and-wine tourism.

The Sonoma Valley Visitors Bureau promotes December through February as olive season, encouraging tourists to visit the area for a variety of events. The season begins with the Dec. 1 blessing of the olives at Sonoma's historic mission downtown.

Interest in high-end California olive oil has grown steadily as the young industry has won awards around the world, said Jill Lee, tour and events manager at McEvoy Ranch in Petaluma.

"So it's kind of like the wine industry was back in the 1970s," Lee said. "Each year it seems like there are more and more producers out there."

McEvoy Ranch has been custom-milling olives for clients for the past two weeks, and plans to start harvesting its own fruit on Monday. The ranch's 80 acres of Tuscan olives are located in a cooler coastal area and ripen more slowly than warmer areas like the Sonoma Valley.

Workers began harvesting olives at B.R. Cohn Winery in Glen Ellen on Wednesday.

"It's the biggest crop I've ever seen," said Bruce Cohn, who has owned the property since since 1974.

It is typical for olive trees to have large crops following light years, but the difference between this year and last was pronounced, Cohn said.

"Last year, we had none. This year we have tons and we don't need it all," Cohn said. "That's agriculture. It's hardly ever just right."

Cohn's 450 picholine olive trees date to the late 1880s, and many have grown far taller than those found in modern commercial olive operations. So instead of shaking the trees with machines, which would send the small olive variety flying in every direction, workers are using long wooden poles to whack the branches.

"It's hard work," said Felipe Martinez, who supervised about 25 workers harvesting at B.R. Cohn. Martinez, who works at Olive Farm nursery in Sonoma, said in the past when he has worked the harvest, his back muscles would ache for days from the labor of repeatedly swinging the wooden pole.

With every blow from the workers, a hail of black, purple and green olives falls onto 100-foot-long plastic tarps. After removing the leaves and branches and sorting the fruit, the olives are taken to McEvoy Ranch in Petaluma to be mashed into the paste from which extra virgin olive oil will be extracted.

It's an expensive process and not a terribly profitable one, even with the light, flavorful oil prized by chefs fetching $25 for a 220-ml bottle, Cohn said. The property's trees, which line the driveway and encircle the bucolic Sonoma Valley winery, can produce just 200 cases of oil.

(You can reach Staff Writer Kevin McCallum at 521-5207 or kevin.mccallum@pressdemocrat.com. On Twitter @citybeater)