Now that the smoke has begun to clear from North Coast vineyards, questions are swirling about whether it will linger in the 2008 vintage.
Grape growers and winemakers closest to the wildfires are concerned that the vines may absorb enough of the unsavory smoke compounds to taint the wines.
"It's definitely a topic everyone is discussing up here," says Tex Sawyer, winemaker at two sparkling wine producers in Mendocino County's Anderson Valley, Roederer Estate and Scharffenberger Cellars.
For three weeks, smoke from wildfires raging out of control in timberlands just to the west have cast an acrid pall over the bucolic Anderson Valley.
The Cold Spring Complex of fires, which has burned 6,500 acres to date, has been one of the most stubborn of the approximately 2,010 separate blazes ignited by a lightning storm that struck June 21.
As of Wednesday, it continued to burn while 95 percent of the other fires in the county scorching 53,000 acres had been contained.
Firefighting helicopters have been regular visitors at winery irrigation ponds, and vineyard workers have been sent home many days out of concern for their health. With the start of harvest just a few weeks away, concern is turning to the health of the grapes.
"We certainly have a concern that something could happen, but we really don't know," Sawyer said. "We're basically just waiting to see what develops."
While Mendocino's wineries may be on the front lines in the debate, some suggest plenty of other wineries need to be aware of the potential problems. They say smoke has been thick enough and hung around long enough that vineyards all over the state could be affected.
"They should be concerned, and so should the wineries in Sonoma and Napa," said Bob Kreisher, president of Memstar North America, a Santa Rosa-based wine filtration company that offers a service to remove smoky flavors from tainted wine.
Government sponsored studies in Australia have shown that exposure for just a few hours to smoke from brush fires is enough to taint the taste in wine, Kreisher said. By comparison, smoke has been hanging over parts of the North Coast for weeks, he noted.
The timing of the fires couldn't have been worse, Kreisher said, because the impact is greatest not when the grapes are close to harvest, but mid-season when they are growing rapidly in size.
The compounds from the smoke are absorbed by the leaves, transferred to the fruit and then released during fermentation, Kreisher said.
The result is wines with a slight bouquet of bacon or wet ashtray, Kreisher said.
Others disagree with Kreisher's assessment, pointing out that he and other companies that claim to remove smoke taint have a vested interest in it being perceived as a widespread problem.
Kreisher gave an impromptu presentation at a meeting of a group of Sonoma vineyard owners and managers last week, and some felt he was long on fear and short on facts.
Nick Frey, president of the Sonoma Winegrape Commission, said Kreisher's talk was informative but highly speculative.
"I would say he was speaking from experience. The question is, is that experience relevant?" Frey said.
One key question Frey has is whether parallels to Australia, where much of the existing research on smoke taint has been conducted, can be drawn with conditions in the U.S. For one, brush fires in Australia often involve eucalyptus trees, which are filled with oils and resins that probably release different compounds in smoke than those from redwood and fir forests.