Smoke from wildfires hangs over vineyards in California’s Sonoma Valley on October 10 2017. Picture: REUTERS
Smoke from wildfires hangs over vineyards in California’s Sonoma Valley on October 10 2017. Picture: REUTERS

New York — Vineyard owners in California’s Napa and Sonoma regions and the Santa Cruz Mountains had planned to harvest grapes over the next few weeks. But with flames threatening wineries and homes, thousands of people have had to evacuate, although some winemakers and winery workers stayed to help fight the fires alongside Cal Fire, the state Department of Forestry and Fire Protection.

It’s hard to grasp the extent of devastation. On Wednesday morning, August 26, Cal Fire reported that in the prior eight days, the LNU Lightning Complex fire engulfing Napa, Lake, Sonoma, Solano, and Yolo counties had burnt 357,046 acres, destroyed 978 structures, damaged an additional 256, and killed five people. One part, the Hennessey Fire in Napa and Lake counties, had accounted for 299,763 acres and was only 33% contained. In Sonoma, the component Walbridge fire had burnt 54,923 acres and is only 19% contained. Down in the Santa Cruz Mountains, a separate conflagration, the CZU August Lightning Fire, had burnt nearly 79,000 acres and destroyed 330 structures.

And that’s just in northern California. In the entire state, one of the biggest fires to date encompasses 700 blazes that have already burnt more than 1.3-million acres — an area bigger than the state of Delaware.

What winemakers face

At Bohan Ranch on the west Sonoma coast, which provides pinot noir grapes to star wineries, George Bohan and his neighbours carved out trenches to hold back the blaze. In Napa, Cal Fire workers ultimately saved the historic Nichelini winery, one of the valley’s oldest, though flames engulfed outbuildings.

Bradley Brown, owner and winemaker at Big Basin Vineyards in the Santa Cruz Mountains, thought the redwood forest to the west of his house and winery would act as a firebreak. He lost his house, but his winery survived. “If the smoke ruins my grapes,” he says, “this would mean huge, irrecoverable loss, yet another strain on our already pandemic-affected business.”  

Fortunately, the predictions of more lightning strikes for northern California for Sunday night and Monday didn’t come to pass. Although fires are still burning, many evacuation orders have been lifted. Cooler weather helped on Wednesday.

Smoke, however, is on everyone’s minds. A thick blanket of it hanging over vineyards for days can severely damage wine grapes with what’s called smoke taint. Wines that result taste and smell like a damp ashtray, making badly affected grapes unusable.  

What happened

“It was a beautiful harvest until two weeks ago,” sighs Stu Smith, founder of Smith-Madrone winery on Spring Mountain. A dry winter and perfect, not-too-hot days and cool nights had brought smaller grapes with more concentration and flavour. Then came 38°C-plus degree heatwaves and rolling power blackouts, followed by almost 11,000 lightning strikes that ignited fires in super dry Napa, Sonoma, and the Santa Cruz Mountains. “Maybe locusts are next,” Smith offers.

So far, there are no official assessments as to how many wineries in these areas have been destroyed or damaged. Besides those mentioned earlier, Gustafson Family Vineyards in Sonoma’s Dry Creek Valley lost its winemaker’s house and the vineyards were partially damaged. Fire on the Sonoma coast came within 200 feet of Fort Ross winery’s tasting room. Fires burnt land at Brown Estate in Napa, though buildings survived. Many winery workers lost their homes.

In Napa, the fires are burning on the eastern side of the valley, in the Vaca Mountains, a range that includes Atlas Peak, Howell Mountain, and prime cabernet territory Pritchard Hill, which is noted for prestigious wineries such as Continuum, Colgin Cellars, and Chappellet.

“A lot of Sonoma isn’t affected,” says Michael Haney, executive director of Sonoma County Vintners. Worrisome areas include Dry Creek Valley, Russian River Valley, and Fort-Ross Seaview on the coast, where pinot maker Jamie Kutch obtains 80% of the grapes for his eponymous wines. “Driving there last week felt like being in The Walking Dead, with smoke everywhere,” he says.

Above the clouds in high-ridge vineyard McDougall Ranch, at 1,000 feet of elevation several miles from the Pacific Ocean in the Walbridge Fire zone, Haney says he found no smoke, and the grapes were ripe.

To pick in any evacuation zone, winemakers have to obtain special access passes from the agriculture commissioner. These are issued as long as there’s no imminent danger of flames.

Picking problems and power outages

With social distancing in vineyards and cellars taking place at the busiest time of the year — as well as a labour shortage — 2020 promised to be stressful enough. That was before the fires.

When the air quality index reaches 151 or above, and smoke comes from a wildfire, a state requirement says wineries must provide N95 masks to vineyard workers. “Because of Covid-19 and our past fire experience, we already had a solid supply,” says Jon Ruel, CEO of Trefethen winery in Napa’s Oak Knoll district. (Despite the fires, tourists showed up over the weekend to taste at Oak Knoll’s outdoor tables.)

The heatwaves advanced ripening, so the picking of chardonnay, riesling, and pinot noir is already well under way. It’s still too early for cabernet.

Some vintners still can’t get to their vineyards, which means their grapes may ripen more than is ideal before they can pick them. Mark Bright, owner of Saison, a Santa Cruz winery, got lucky: an area he’d cleared to plant aligoté grapes acted as an essential firebreak.

Out on the west Sonoma coast, at famous Hirsch vineyard, Jasmine Hirsch frets about how picked grapes can get to such high-profile winemaker clients as Littorai if the roads remain closed.  

Power outages compound problems in the cellar, where temperature-controlled vats are used for fermentation, and cooling is needed to age barrels of wines in the absence of a deep cave. Larger wineries have generators, but many others — especially small ones — do not. Some wine growers are taking their grapes to someone else’s winery.

The biggest worry now

“Our biggest concern is smoke taint to the grapes,” explains Aaron Pott, who makes his eponymous wine on Mount Veeder and serves as a consultant to a number of wineries around the valley.” There’s smoke everywhere,” he says.” It looks like Mars.”  Pott was driving around on Monday, checking grapes at clients’ vineyards — at least, where he could. On Pritchard Hill, fire was burning around highly regarded Stagecoach Vineyards, he says, and luxury resort Meadowood was evacuated.

The two dozen winemakers, grape growers, and winery owners I spoke with echo his concern. Grapes with smoke taint make unpalatable wines, so top wineries may choose not to pick them at all and skip a vintage, or sell off the wine as bulk wine. Sometimes, Pott says, the wine tastes all right at first, and taint shows up only after it’s been aged a few months.

Dana Grande, grower-relations manager at Sonoma’s Jordan Winery, e-mailed to say that “spider webs look like ashtrays on some vines. Growers are blowing the fruit areas with air before picking to minimise ash remaining on the grapes.”

A scientific scan

Gordon Burns, co-founder of ETS Labs in Napa, prefers the term “smoke impact” to “smoke taint.” He says the taste effect is caused by chemical compounds in wildfire smoke that have been absorbed into grape skins and released during fermentation. He tests for two key compounds (guaiacol and 4-methylguaiacol), and winemakers use his analyses to make decisions as to whether they should pick grapes at all, or alter the wine they make.

The analysis is necessary because there are otherwise too many variables — how long the grapes are exposed to smoke, how dense it is, the variety of affected grapes, and so forth — to predict which grapes are affected.

“Small amounts of the compounds are not necessarily a death knell,” adds Burns. But since the compounds are concentrated in the grape skins, where the fermented juice macerates with the skins for days to pick up colour, flavours, and tannin — as happens for cabernet — those wines are more at risk. Many wineries may choose to make rosé from their red grapes this year, as that wine stays on the skins only briefly.

On Monday night, a hopeful Tor Kenward of Napa’s Tor wines received the ETS Labs report for cabernet grapes from a famous Oakville vineyard that he uses for one of his several single cabernets. They were negative for smoke, but he’ll have them tested again as they ripen further.

 “It’s all about testing, testing, testing,” says Philippe Melka, winemaker of his own wines and star consultant to several dozen famous Napa wineries. “We have to test berries to see if we want to cancel the harvest for some vineyards.” Grape contracts include the right to reject the grapes if they’ve been compromised by smoke.

The future

“We have to figure out something different,” says Craig Becker of Somerston Estate, high in Napa’s eastern hills, who lost all the grapes in his 144-acre vineyard in 2017. Last week, 70% of his 1,615-acre property burnt, including a part of the vineyard. “If we lose our grapes to taint again this year, that’s two lost seasons out of the past four. And that’s not sustainable.” 

After the huge 2017 fire, Pritchard Hill’s Chappellet Winery bought its own fire truck, installed pressurised water tanks, and hired its own in-house, experienced fire chief.

Longtime Napa grape grower Tom Gamble has been looking for answers in the kind of land management balance practised by American Indians. He says his family’s 6,000-acre ranch near Lake Berryessa, near the heart of one of the fires, pulled through because he clustered buildings in order to let firebreaks work better. He uses livestock to restrain vegetation growth, balances the brush lands, and encourages a good supply of hawks and eagles to keep out ground squirrels, whose holes provide ways for fire to spread underground. “We have to start thinking seven generations down the road,” says Gamble.

Early on Wednesday afternoon, Trefethen CEO Ruel e-mailed that the skies in his part of the Napa Valley were blue, and he had spotted some hot air balloons. For now, keep your fingers crossed — and perhaps, buy a few bottles of your favourite labels to help winemakers keep going.

Bloomberg 

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