Tuesday, March 22, 2011

"....burned grapes...." High temps, exacerbated by high UV radiation perhaps???


Weathering climate change with Napa Valley’s grapegrowers

REBECCA HUVAL Napa Valley Register | Posted: Sunday, March 20, 2011 12:00 am

WEDNESDAY - FEBRUARY 09, 2011 - OAKVILLE, CA - Katey Taylor, a viticulturist with Robert Mondavi Winery in Oakville points to a Christmas berry tree planted along the banks of Doak Creek. The area around the creek has been replanted with native species. J.L. Sousa/Register

Grapes drooped off the vine last summer like sacks of raisins.

Rows and rows of fruit shriveled as Will Drayton, a viticulturist at Treasury Wine Estates, examined them with dread. Low in sugar and high in acid, this type of grape, he said, “makes terrible wine.”

On each piece of fruit a brownish-pink spot pointed like an accusing finger in the direction of the sun.

“Whole blocks burned,” he said.

To adapt to global warming, Treasury and others who grow Napa Valley wine grapes have recently tweaked their growing techniques. The trend isn’t new — vineyards have been shifting toward “green” for decades. Change has been spurred on by anti-herbicide activism, Napa River restoration and worldwide sustainability movements.

In Napa, sustainable farming “is not just strictly an environmental thing,” Drayton said. “It makes healthier grapes.”

Adaptations range from cutting back on pesticides to increasing Napa River shade that cools down the water for endangered steelhead and salmon.

It takes a sophisticated grapegrower to juggle all the needs of land and water, experts say.

“There’s this notion that farmers aren’t smart,” said Laurel Marcus, executive director of the California Land Stewardship Institute in Napa, “and that’s just not true. It’s a combination of accidents and practical knowledge.”

Accidents such as the burned grapes have led grapegrowers to pursue research. The Napa Valley Vintners commissioned a study of global warming’s potential effects on the wine industry.

Because of earlier studies, they were worried the valley was warming. Instead, four years of research and 12,000 data reports later, scientists released surprising findings this winter: despite heat spikes, global warming may cause Napa Valley to cool down.

This doesn’t count as good news.

“Nobody wants to see anything change,” said Chris Howell, a member of the Napa Valley Vintners Climate Study Task Force. “We’ve been growing cabernet sauvignon over 100 years. Climate change is a global issue, but we will deal with it and live with it locally.”

To deal with climate change, Napa growers have changed their mindsets.

In a valley in the Stags Leap grapegrowing region, a blanket of grass and wildflowers weaves between gnarled vines that will one day bear petite sirah. California poppies, rose and crimson cloves, henbit, barley and pineapple weed — these make up the cover crop.

The bed of weeds serves as a compost, breaking down nitrogen in the soil so that vine roots can absorb it.

Nearby, a red-tailed hawk surveys the vineyard. It feeds off the mice, squirrels and insects supported by the cover crop in Stags Leap.

Growers weren’t always so laissez-faire.

Fifteen years ago, vineyards were doused with pesticides and scoured bare between the vinerows. Insects, weeds and pests were battled as archenemies of the holy vine.

Then, attitudes changed. Where the land was once bald, farmers left weeds and insects wild. Pesticide use was reined in.

Otherwise, “You kill off all the bugs you’re trying to kill as well as the beneficial insects that would be naturally controlling your pests,” Drayton said. “Then you’re stuck in a vicious cycle of trying to spray all the time.”

Over decades, this more holistic acceptance of wildlife has led to an overall attitude change still at play. Vineyard managers invited insects back by cultivating cover crop, built birdhouses and erected solar panels.

They have even sacrificed the bottom line.

Since 2004, Laurel Marcus has asked vineyard owners to slash vine rows to make way for the Napa River. They plant trees and expand shorelines where grapes — and, in turn, money — once grew.

Despite the revenue tradeoff in some cases, Napa Valley grapegrowers have signed up more than 50,000 acres to the voluntary California Land Stewardship program to improve agricultural practices.

“They have to see there’s a value in it for them,” Marcus said. “Vineyard managers know the environment around them. They know their creeks better than anyone else.”

At Treasury Estates, managers watched as the Napa River flooded regularly. “You couldn’t see the vines,” Drayton remembered. They donated 3.4 acres of the Beringer vineyard, which should alleviate their flooding problems in addition to helping the river.

The 55-mile Napa River erodes less with expanded shorelines and supports more biodiversity among riverside plants and animals.

Some grapegrowers cultivate their own biodiversity. They plant a variety of native species beside the Napa River to shade the water and cool it down to 60 to 65 degrees, the ideal temperature for salmon.

In Oakville, viticulturalist Katey Taylor bends down to examine the small seedlings the Robert Mondavi Winery planted beside the Tokalon Ranch stretch of the river.

“Snowberry,” she said, pointing to a white bulb. “California rose, coyote bush, monkey flower.”

Nearby, a birdhouse, one of 80 on the vineyard, welcomes bluebirds. Three years ago, the company also planted six hedgerows to shelter owls, raptors and songbirds on their 1,400 acres of vineyards.

“I think there’s been a shift,” she said, “of people recognizing we need to coexist with the vineyards and the land.”

But that sustainability can come with a steep price tag. Far Niente Winery paid $4.2 million in 2008 for 994 solar panels floating on their farm pond.

They didn’t pay millions just for an easy conscience, said Larry Maguire, president of the winery. The system was built “both for an economic reason and the socially responsible reason.”

The long-term investment is clear from their electric bill. Since April 2008, the company’s PG&E bill plummeted from $110,00 yearly to a more manageable number — $0.

The winery actually creates an excess of energy that cycles back to Pacific Gas & Electric’s grid. On a recent cloudy morning, the panels produced 229 kilowatts. The winery used 52.1 kilowatts at that moment and donated 176.9 to PG&E.

The electric company did pay the winery once — a one-time $1 million rebate — but there’s no additional financial incentive for the winery to save more energy than it already does.

If PG&E paid the company for its excess energy, “We would be encouraged to replace light bulbs in our cellars,” Maguire said.

Still, the winery already has financial reasons to invest in the environment and save energy. In Napa Valley, “We live in an economy where our revenue is based on the weather,” Maguire said. “We like the planet just the way it is.”

Instead, the planet has changed in increments.

In the Napa Valley, climate reports have shown nighttime temperatures shifting more than daytime highs. Overall, the nights have become slightly warmer by less than one degree over 60 years, according to the climate report commissioned by the Napa Valley Vintners.

The same geography that’s ideal for many wine grapes and keeps the temperature moderate might turn Napa into an anomaly of global warming.

Thanks to the Pacific Ocean, warmer temperatures in the Central Valley suck cool air into Napa Valley.

Yet the summer heat spikes persist.

“We have been very fortunate because of the marine influence and the dampening effect it has,” said Jim Verhey, director of Napa Valley Grapegrowers, “but what’s really happened is weather has gotten more extreme.”

Extreme highs — up to 114 degrees — shriveled many grapes in Napa Valley last summer. Will Drayton declared the majority of a vineyard block unfit for wine. It produced one ton of grapes per acre instead of the 3.5 tons it normally makes.

So in the same spirit of the solar panels and river bank restoration, Treasury Wine Estates adapted.

Growers replanted the desolate block where Drayton found shriveled grapes. They changed the orientation of their vine rows to northeast by southwest so that the sun doesn’t pound on the grapes at its summertime zenith.

To further shade the fruit, growers inserted “cross arms,” wires that encourage branches to bend over the grapes they produce, protecting them like an umbrella from the sun.

“How do we deal with a change in climate, short-term and long-term?” Verhey asked. “It’s hard.”


  1. There are lots of confusing points being made in this article--first of which is that we should not look at unique weather incidents like heat spikes as climate change. Napa Valley typically experiences 10-14 days with temperatures exceeded 100 degrees--this past year it was 3. And while some damage was done in some vineyard sites because vineyard leaf canopies had been opened up to provide for more sunlight to help ripen the fruit because the season had been on the cool side to date--that's what caused the damage. That said, the harvest came in at one of the top three most abundant in the past decade (see the Napa County crop report)--so the notion of extensive fruit loss or damage is just not true--and everyone is thrilled about the quality they are tasting in the grapes and wine. This writer should do better research and not take single incidents out of context.

    Terry Hall, Napa Valley Vintners

  2. Good to know... thanks for the comment, Terry!