Northwest Smoke Plume Shields Grapes

Winemakers say risk of smoke taint is minimal

by Peter Mitham
wine grapes vineyard northwest smoke
The sky above Cowhorn Vineyard was filled with smoke recently as a result of rampant wildfires burning in the Pacific Northwest.

Jacksonville, Ore.—Thick smoke hangs over Cowhorn Vineyard in the Applegate Valley, just 5 miles from the Miller Complex Fire, a 28,670-acre wildfire sparked Aug. 14, when thunderstorms rolled through the area. Smoke from that fire and the Chetco Bar conflagration that has grown to 176,770 acres near Brookings, Ore., since July 12, have made this year’s smoke heavier and thicker than usual.

The quantity of smoke is so great it has reached north to British Columbia, where air currents have added plumes from Washington wildfires, including blazes in the Columbia Gorge on the north slope of Mount Hood. All told, the National Wildland Coordinating Center lists 29 major fires throughout Washington and Oregon.

British Columbia has its own fires to contend with—the largest being the massive Plateau fire on 1.3 million acres of forest and rangeland in the province’s interior. Since the July lightning strikes that sparked the 19 fires now burning as one, smoke has rolled across the province and as far south as Vancouver and Seattle.

Ann Sperling of Sperling Vineyards in the Okanagan Peninsula told Wines & Vines, “We have an early variety called Bacchus to pick in about a week, so we will likely do some testing on it to get a sense of the level of concern, if any. In the past we haven't had to deal with any smoke taint issues, so we are taking a conservative approach, but colleagues in the south Okanagan have suggested that the levels of smoke this year are minor compared to 2015.”

The start of wildfire season well before véraison initially meant few grape growers were worried. Shifting weather patterns also gave hope that maturing fruit wouldn’t be significantly impacted. The smoke simply wasn’t lying in vineyards heavily enough or long enough to make a difference.

But it’s September, and anyone traveling the breadth of the Northwest for the past several weeks knows that the combination of plumes has made the smoke an almost constant companion across the region for nearly two months. Many are calling its extent unprecedented.

“Now we’re into troublesome territory,” says Bill Steele, who runs Cowhorn with his wife, Barbara. The 2,000-case winery focuses on Rhône varietals. “There are multiple fires around us, and it’s hung around a lot longer than (in 2014).”

While smoke taint is a concern, a key issue is the lack of solar radiation reaching the vines. While clouds may let ultraviolet light pass, the particulate matter that determines the density of smoke blocks it altogether. To address the issue, Steele is turning on his overhead sprinklers once a week to rinse off the vines.

“I hope that’s going to help. It’s certainly going to allow the interaction of the plant with UV to be more efficient than if it’s covered with ash,” he said.

Brix levels are currently in the mid-teens, and while Steele likes to use acid as an indicator for when to pick, he’s hoping fruit samples he sent to the lab this week will yield insights into the exact impacts smoke is having on the composition of his fruit.

Steele typically barrel ferments his white wine grapes, but he will likely scale back his use of new oak this year from the usual 20% to 25%.

“Any oak on a white is going to increase the smokiness, so I think that will go way down,” he said. “I can get away with some smoke in the reds, but I obviously can’t get away with any of it in the whites. So for the whites, it’s going to be a reduction in new oak, and in the reds, I think I’ll be a little lighter touch in my extractions.”

Washington winemaker Kerry Shiels said wildfire smoke at DuBrul Vineyard near Sunnyside, Wash., in the Yakima Valley AVA has reduced air quality but isn’t a major concern.

Shiels dealt with smoke taint during a stint in Napa in 2008, prior to becoming winemaker at Côte Bonneville, and says wildfire smoke has been a present but unclear risk. This is why she entered a collaboration with Washington State University assistant professor Tom Collins last year to better understand the risks wildfire smoke poses to vineyards (see “Smoke Taint Addressed as Northwest Harvest Begins”). The partnership continues this year.

“When the air quality deteriorated (Sept. 5), we started monitoring PM (particulate matter) levels in DuBrul Vineyard, in the fruiting zone,” she told Wines & Vines.

Since particulate matter levels have typically been low, she isn’t expecting any impacts but is keeping tabs on matters. The critical variables are always the duration and intensity of the smoke, and maturity level of the fruit.

“It’s too early to tell at this point what the effects will be in any particular vineyard, or throughout the Northwest,” she said. “One thing is sure, though: This a potential issue for vineyards all over the West Coast.”

Containment of the Chetco Bar and Miller Complex fires aren’t expected until late October, while the massive fires in British Columbia could well be burning until spring. Still, there’s hope in the forecast, at least for Steele, with rain on tap for tonight. This could help tamp down the smoke and assist fire crews.

However, he also takes a philosophical approach, acknowledging that wildfire is one more environmental factor to take into account as he tries to make his wines as much in harmony with nature as possible.

“When you’re making fine wine, you have to be comfortable on the edge, so that’s what I’m trying to do,” he said.

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