Early Bud Break Brings Frost Worries

Growers in some regions have had to turn on wind machines or sprinklers

by Andrew Adams
The Carneros AVA that straddles Napa and Sonoma counties in California showed signs of growth this weekend.
San Rafael, Calif.—With bud break occurring in vineyards throughout California, it appears 2015 could be another early vintage and one that hopefully is not marked by frost.

Bud break has now been reported from all of California’s key wine grape regions from Temecula Valley in the south to Mendocino County in the north. Growers in Mendocino County have already had to turn on wind machines or sprinklers to protect emerging buds from temperatures that dipped into the low 30°s.

It’s not uncommon for overnight lows to reach into the 30°s or lower in California. In 2008, a series of frosts limited yields throughout much of the state, and a lengthy stretch of freezing temperatures in late April severely reduced the 2011 crop in Central Coast growing areas.

“We thought last year was early,” said Steve Andrews, owner of Oak Mountain Winery in the Temecula Valley, who said he’s seeing buds pushing in his hillside vineyards.

North Coast
A few nights of below-freezing temperatures in Mendocino County already have done some damage, said Joe Webb, owner and winemaker of Foursight Wines in Boonville, Calif., and the current president of the Anderson Valley Winegrowers Association. Webb said he knows of one vineyard near Philo, Calif., where the owner opted not to frost protect because less than 1% of vines where showing growth. Unfortunately, what was showing was fried.

Webb said he just completed double-pruning Foursight’s 15 acres of estate vineyards and expects to make the final pruning in mid-March. He said last year was about two weeks early, on average, and this year it looks more like three. Vineyards set to canes are about three to four weeks early.

He said he installed a wind machine last year as well as a Davis Instruments Vantage Pro2 weather station. Data from the weather station, as well as from others in the county, is sent to the private weather firm Fox Weather in Fortuna, Calif., which provides frost forecasts for Mendocino County and other regions in California.

Better data ensures more accurate forecasts, so Webb knows when to turn on the wind machine or just wait for temperatures to drop to 32° F or colder and turn on the sprinklers. “We’d rather not have the noise and burn the propane if we don’t have to,” he said of the wind machines.

bud break
The wooly tips of grapevine buds emerge from a vine in California's Alexander Valley AVA.
The group Mendocino WineGrowers Inc. also has established a system to alert neighbors living near vineyards with an email or text if a frost is expected, so they’re not rattled or annoyed by the noise of wind machines and complain about them.

Webb said the prospect of another early harvest is not ideal, as August pick dates can often conflict with bottling. “It’s certainly not optimal, and I think what a lot of people figured out last year is it’s a huge logistical issue,” he said.

Jason McConnell, winemaker and owner of Rivino winery and vineyards located near Ukiah, Calif., on the Russian River said he had to turn on his sprinklers last week, but the vines are faring OK. “It was more localized bud break last week, but we are now basically out across the property,” he said. “There have been two very long frost-control nights so far, which are just a big drain on everything: water, fuel, sleep,” he said.

McConnell and Webb both said they’d like to see more rainy and cloudy weather to keep temperatures up as well as fill ponds that can be used for frost protection in the spring or irrigation in the early summer.

David Fanucchi is the owner of nearly 60 acres of mostly Cabernet Sauvignon and Merlot vineyards in the Alexander Valley of Sonoma County. He said he’s seen bud break in just one block of Merlot on his property yet added many white variety vineyards located nearby are starting to push. “Everything is probably going to start soon,” he said.

 Fanucchi said he’s going to closely keep track of the weather and delay on any possible frost protection with sprinklers because it’s a sensitive topic in Sonoma County. Growers in Sonoma and Mendocino counties who use water for frost protection are now required to be part of a state-mandated water use plan intended to decrease draws on the Russian River. The requirements came after some juvenile fish were found dead in the river following a frost event a few years ago. “We don’t want our name in the paper as fish killers,” Fanucchi said.

Still, Fanucchi says “the whole thing is a good thing” and the required stream flow monitoring stations will ensure growers don’t get blamed for any drop in water levels and if there are any issues they can be quickly and effectively resolved. “With the monitoring system we’ll find out if there’s a problem some place,” he said.
Santa Cruz Mountains
Some vines and vineyards in the Santa Cruz Mountains were off to a quick start in mid-January, but vineyard consultant Prudy Foxx, who manages several properties in the area, said those were fairly isolated cases and in general things have slowed down a bit.

She said because the region is close to the ocean, and most vineyards enjoy good air drainage, a serious frost is rather rare. However, she said it’s common for growers to double-prune Pinot and vineyard locations that are susceptible to frost.

Foxx said the early bud break could be a result of warmer than normal soils that have kept the vines more active during December and January, prompting them to start the season earlier. The grapegrower noted she has a few young vines with shoots measuring 3 feet long, but she’ll likely just hedge those back so the green wood doesn’t serve as a springboard for disease.

A hard frost isn’t likely, but Foxx said one never knows what to expect. A weather system moved in earlier this week that brought much-needed snow to the Sierra Nevada and unsettled weather to other parts of Northern California. Foxx said on Feb. 28 she drove through a rain shower, found hail stones on one property and then snow on another. “It was really weird; I’ve never seen anything like that,” she said. “This season continues to surprise me.”

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