California vineyards find night harvests yield benefits

By Elizabeth Weise, USA TODAYUpdated 8h 28m ago

NAPA, Calif. – At 4 o'clock in the morning, Shafer Vineyards is alive with light and motion. The sun won't be up for more than three hours, but lines of pickers are moving methodically down vines full of ripe cabernet sauvignon grapes. They're lit by huge bright lights mounted on tractors trundling alongside.

The scene at this vineyard is part of a worldwide practice that's increasingly the way all wine grapes are harvested — in the dead of night. It results in better wine, lower energy costs and happier workers.

Daytime temperatures in the 90s and above change the sugar composition of grapes. Picking at night when sugar levels are stable keeps "surprises" from happening during fermentation such as wild yeast starting fermentation, says Shafer's Andy Demsky.

Pickers can work longer hours in the lower temperatures and also avoid the "wasps, bees and rattlesnakes" that come out during the day, he says. And the grapes are picked cool, saving energy because they don't have to be pre-chilled before they're crushed.

Harvesting grapes at night is common worldwide, says Gregory Jones, a viticulture expert at Southern Oregon University in Ashland.

By Jack Gruber, USA TODAY

Hot daytime temperatures change the sugar composition of grapes. Picking at night, when sugar levels are stable, keeps "surprises" from happening during fermentation, says Shafer's Andy Demsky.
"I have seen night harvests in South Africa, Australia, Argentina, Chile, Europe … you name it.

California produces 61% of U.S.-made wines, according to the Wine Institute, and about two-thirds of those are from grapes harvested at night, says Nat DiBuduo, president of Allied Grape Growers, a California winegrape marketing cooperative.

It's better for the workers, DiBuduo says. "I don't want to be harvesting food out there at temperatures where it's not safe for the people," he says.

At Shafer Vineyards, president Doug Shafer is out in the 8-acre field being picked this early October morning, watching over the process that's the culmination of a year's growth.

"We'll get 30 tons of grapes" in tonight, he says, consulting with Alfonso Zamora-Ortiz, the vineyard's director of operations.

"In the old days, by 1 o'clock in the afternoon the guys would say 'We're done, we're fried, we can't pick any more.' When they pick at night they can pick more because it's cool, " Shafer says.

In the pre-dawn cold the hired crew of veteran harvesters moves quickly down long rows of carefully pruned grapevines, following a light tractor and a half-ton bin. Their harvest knives flash under the lights as a slight flick of the wrist cuts off each bunch of grapes. They drop them into the white plastic bins at their feet, which they kick along at the roots of the vines as they move down the row.

During breaks the men and a few women on the crew pull out tiny whetstones. The snick-snick of their blades being sharpened is the only sound beyond muted conversations in Spanish across the rows.

"Night time is better. It's too hot in the day, you're sweating," says Roberto Flores, one of the pickers. "Starting at 4 a.m. is good. We get seven hours sleep at night."

At Ridge Vineyards in Cupertino, Calif., David Gates, vice president of vineyard operations, says they do night harvests when daytime temperatures get up over 100 degrees. "Then the fruit can get as hot as 110, and you want it at 55."

Ordinarily to bring down the temperature "you run it through a cold bath or a heat exchanger, or big wineries have jackets on their stainless steel tanks," but that all takes energy.

Statewide, during crush California's 3,364 wineries are rushing to turn the ripe fruit into a slurry that's pumped into 4,000 gallon steel tanks for the first round of fermentation. The energy savings from not having to cool 3.99 million tons of that slurry is enormous, though no exact figures are available, says Allison Jordan of the California Sustainable Wine Growing Alliance.

Cool fruit also means better control, and winemakers want total control.

"Chilling the grapes gives the winemaker better control over the fermentation process, says Mark Matthews, a professor of viticulture and enology at the University of California-Davis.

Night harvesting got its start as early as 1970 or 1971, when the first mechanical grape harvesters began to be used in the San Joaquin Valley in California and in New York state's wine growing areas, says Phil Scott, owner of Ag-Right Enterprises in Madera, Calif. The company makes grape harvesters.

Machines didn't care if they worked night or day.

Gates of Ridge Vineyards remembers working with jury-rigged lights in "1982 or 1983" when he was at R.H. Phillips Winery. "We ended up with a little generator on a half-ton bin tractor and some standard 8-foot fluorescent lights up above and underneath."

Today people just rent the same kind of diesel-powered light towers on trailers that roadwork crews use, which typically carry four 1,000 watt lights. Though even that's changing, Gates says. He's seen some vineyards where they "don't even use lights, they just have head lamps on the guys' heads."

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