vineyard wild fire
Santa Rosa, CA / USA - 08 20 2020: Wide view of smoke emanating from the Walbridge Fire behind one of many vineyards in the area. Photo: By Gibson Outdoor Photo / Shutterstock

By Kevin Hecteman
Assistant Editor, Ag Alert

Reprinted with Permission from the California Farm Bureau Federation

A record-setting year for wildfires has left Northern California winegrape growers facing an uncertain future on a number of levels.

The uncertainties include the size of this year’s crush.

Jeff Bitter, president of Allied Grape Growers in Fresno, provided an early estimate of 3.2 million to 3.5 million tons, down from the expected crop of 4.15 million tons, which would have meant an average-sized crush.

The drop reflects short 2020 yields—the crop was expected to be lighter to begin with—along with grapes rejected or unsold due to smoke exposure.

Bitter estimated smoke-related losses at 15,000 to 25,000 tons in the northern interior; 75,000 to 100,000 tons on the Central Coast; and 150,000 to 200,000 tons on the North Coast. He said Napa, Sonoma and Monterey counties had suffered the worst from smoke exposure in terms of crop value.

David Rosenthal, a Lake County grape grower, said he’d heard estimates of “anywhere from 150,000 to maybe 350,000 tons being rejected” on the Central Coast and North Coast, plus some in the Lodi area.

“That could be 3% to 10% of the crop, almost,” said Rosenthal, who represents Lake and Mendocino counties on the California Farm Bureau Federation Board of Directors.

Karissa Kruse, president of Sonoma County Winegrowers, said her county’s farmers expect more than 50,000 tons of grapes to go unpicked because of marketplace dynamics, wildfires and COVID-19 pandemic effects on wineries. About 70% of the county’s grape growers expect to lose at least some of their crop because of smoke-exposure concerns, she said.

“We estimate between 25% and 30% of the Sonoma County winegrape harvest will go unpicked due to the pandemic and fires,” Kruse said. “We are also still waiting to learn what wines will be made this year. So far, we have identified approximately a $150 million loss to growers.”

Rosenthal said farmers with crop insurance were able to leave grapes on the vine and file claims, while others ended up selling at a discount.

Exactly how much smoke exposure it takes for a winery to turn down grapes is a subjective matter.

Glenn McGourty, a University of California Cooperative Extension viticulture advisor emeritus in Lake and Mendocino counties, said the level of tolerance for smoke compounds in grapes—especially guaiacol and 4-methylguaiacol—varies from winery to winery.

“It’s creating a lot of problems, as you could imagine,” McGourty said, noting that research is underway to determine thresholds.

One pilot study conducted in Lake County in 2018 found that blind tasters could first sense smoke compounds in wine at 6 parts per billion.

“By 10 parts per billion, it became kind of clear that something was wrong with the wine, and by 20 parts per billion, it was usually overwhelmingly clear that the wine was defective,” McGourty said.

McGourty and his colleagues set out to learn whether all vineyards are affected equally, or whether factors such as proximity, elevation and wind direction are in play. The study was able “to show pretty clearly that proximity to the fire makes all the difference in the world,” he said.

“The closer you are to the fire, the more trouble you’re going to have, if the wind is blowing fresh smoke through your vineyard,” he said.

At the peak of the fires, laboratories that process smoke-exposure tests found themselves with so much business that turnaround times stretched out to nearly two months.

“That’s starting to clear out, because there’s more and more labs that are now doing these checks that are popping up all over,” Rosenthal said.

Bitter said some backlog remains, but the appearance of more labs and machines has helped. In addition, the California Department of Food and Agriculture and UC Davis offered their labs to help.

In planning for the 2021 crush, Bitter said the wine business will be thinking about laboratory capacity.

“How do we best plan for something that you can’t plan for?” he said. “There’s some talk in the industry about how to manage the load of testing when we have a year like this.”

Bitter said warm, dry October weather sparked a late-season grape-buying spree.

“That included some grapes that had previously been rejected for smoke exposure by other buyers,” he said. “It’s not about the same buyers coming back in, but other buyers coming in late in the season—offering fairly low prices, of course—knowing that if a grower still had grapes on the vine in October, it’s probably for a reason. Either he was rejected from another contract, or just the market wasn’t active enough because of the smoke exposure for him to have sold his grapes previously.”

Any unsold crop will be dropped on the ground “so it’s not overwintering on the vine,” Bitter said. Leaving unsold grapes on the vine “could encourage pests and disease,” he added.

Rosenthal said while some grapes might be showing worrisome smoke levels, the wines themselves look better.

“We’re looking really, really hard every week at all of our wines, and so far—knock on wood—they’re looking pretty good,” he said.

As for the other prime issue in the grape business, oversupply, Rosenthal said, “Between the light crop and rejected grapes from smoke taint, we should be in a fairly balanced market right now.”

Bitter said there might still be a glut on the higher end of the market, as shoppers shifted amid the pandemic from buying more expensive wine at tasting rooms or restaurants to less expensive products at grocery stores.

“What that means is, maybe the overall market is balanced with supply, but it’s going to put some downward pressure on those guys producing out of the coast to sell cheaper—in essence, to move their prices down, whether it’s grapes or wine, to be more in line with where the consumer wants to buy today,” Bitter said.

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