In the dark of night, the Pellenc machine rolled like a giant Transformer-like insect through the vineyard, seemingly swallowing up vines as it gently shook the chardonnay grapes free.
The canopies trembled almost imperceptibly as the mechanical harvester approached at a little more than 2 miles per hour, its lights gleaming like beady eyes staring down the vineyard rows.
As it passed, the valuable fruit fell softly from the vine and was ferried to a mechanical sorter, leaving behind only the empty stems and gently brushed leaves that quivered in the midnight air.
It's a scene that's becoming increasingly common in Sonoma County, as wineries and vineyard managers look for more cost-effective ways to harvest their grapes, and the number of available seasonal farm workers decreases.
In Sonoma and Napa counties, the percentage of vineyards harvested by machine has been growing by 3 to 4 percent every year, said Pete Opatz, vice president and senior viticulturist of Silverado Premium Properties. His company, which farms 3,500 acres in the two counties, harvests about 45 percent of its crop with machines.
"The trend towards mechanization has been a long-standing trend that continues to grow really over the last 10 years," Opatz said. "Will the labor shortfall push the line more vertical? Of course it will."
Meanwhile, grape growers are saying there's a shortage of seasonal workers available to help with the harvest this year, a trend caused in part by the faltering U.S. economy and tighter restrictions on the border with Mexico.
"As that labor pool becomes more and more difficult to tap into for agriculture, or any work...I see more and more mechanization of our industry as time goes on," said Don Wallace, president of Dry Creek Vineyard outside Healdsburg.
The Australian wine industry has long had a smaller labor pool than it needed during harvest, and as a result, mechanical harvesting is far more common there, Wallace said.
In California, many farm workers hail from Mexico and return there after harvest, but stricter immigration policies are making that journey more difficult, said Casimiro Alvarez, regional director with the United Farm Workers.
"It is hard for people to come back to continue working in the fields," Alvarez said.
Many vineyard managers need about twice as many workers during harvest as they do throughout the rest of the year, meaning harvesters must find other sources of income throughout the year.
"So, what are those workers going to be doing in the non-harvest period?" asked Chris Paige, CEO of California Human Development, which provides training and services to farm workers. "Typically they would be in some kind of non-agriculture job, possibly hospitality or construction. So to the extent that those are down, those workers wouldn't be available during the harvest."
The Healdsburg Day Labor Center, part of California Human Development, was receiving calls from vineyard managers requesting help with harvest this weekend, Paige said.
At the Graton Day Labor Center, coordinators used to call vineyard managers to say they had people available to work. But now they don't have to, because the vineyard managers call them, said coordinator Carlos Lopez. "It's a different game now," Lopez said.
Some seasonal laborers have left because of anti-immigration sentiment, and because wineries are becoming more careful about checking identification of pickers, Lopez said.