As he walks down a row of pruned zinfandel vines, Russ Messana plays a waiting game.
His family’s Bastoni Vineyard on Riebli Road was right in the path of the Tubbs fire, but his house and 19 acres of vineyards were mostly unscathed — with the exception of some vines along the edges of the property.
Those rows suffered significant heat damage, evident from the bent metal stakes and melted hoses along the trellises of his hillside vineyard in the Fountaingrove District wine region.
Messana points to the grayish color of a dormant vine that appears not to be damaged by the fire.
“It’s supposed to look like this,” he said.
He then moves nearby to another vine and discouragingly notes: “They’re totally black and crispy.”
Overall, however, Messana is optimistic: “Grapes, they’re hearty plants,” he said.
Like other North Coast grape growers, Messana will not know how much harm has been done to heat-damaged vines until a few weeks after bud break, which should occur by mid-March at the latest.
Vintners then will be able to determine if the shoots are growing normally, or if their vines have suffered significant damage that may force vintners to replant them at considerable expense.
“We don’t know what’s going to happen,” Messana said.
The one saving grace for the industry is that the number of heat-damaged vines is incredibly small.
A recent survey by Sonoma State University’s Wine Business Institute found that 99.8 percent of the region’s vineyards — or 138,937 of the 139,204 acres of vineyards on the North Coast — were not affected by the October fires.
But any damage can add up quickly on the North Coast, which yielded $1.5 billion of grapes in 2016. Preliminary figures for the size and value of the 2017 crop will be released Friday.
Most of the vines that were damaged are within regions where the blazes quickly plowed through vegetation, such as the Fountaingrove district, the Sonoma Valley and Napa County’s Atlas Peak area.
But even in the areas struck hardest by the October wildfires, there is reason for hope, said Mark Greenspan, president of Advanced Viticulture Inc. of Windsor.
“It’s pretty hard to kill a vine,” said Greenspan, who has examined several vineyards that suffered heat and fire damage. “Even if you kill the top part, there’s a good chance the root system is still alive.”
Greenspan said he is paying more attention to vine trunks that were scorched because that could pose a greater problem to the vine, given the crucial role they play in the plant’s vascular system.
In addition, bud growth occurred on some fire-affected vines a few weeks after the blazes, he said, presenting another problem.
“The vascular system got disrupted,” he said of those vines. “It’s hormonally screwed up.”
When he is out inspecting vines, Caleb Mosley, senior viticulturist at Michael Wolf Vineyard Services in Napa, cuts into the vine with a knife and hopes to see “creamy white material” of the cambium layer tissue. But the knife test can only tell so much.
“The tricky part is how much of that plant has been damaged?” Mosley said. “How much has the sap and water flow been damaged?”