Vineyards deal with ‘noble rot’

NAPA, Calif. — Things got fuzzy in the Dolce vineyard this harvest. The mold known as botrytis sneaked in with early rains, and once-pale green semillon grapes shriveled into purple, furry blobs.

The phenomenon was a real headache for some grape growers — particularly those harvesting chardonnay. Crews picked around the clock to beat the fast-moving blight, a common plant malady that is often what’s to blame for making your strawberries go funky in the fridge.

But no one cursed their rotten luck at Dolce, producer of a rare dessert wine that relies on botrytis — aka “the noble rot” — for its sweet, honeysuckle character.

“For us it’s a good thing,” said Dirk Hampson, who created Dolce in 1985 and is director of winemaking and a partner in its sister Napa Valley winery, Far Niente. “We’re getting ideal conditions.”

This was an unusual weather year for wine grapes, starting with a cool, wet spring in many regions that slowed ripening. A summer heat wave in some areas slowed things down again when vines shut down to conserve energy.

The subsequent late harvest and relatively early rains set the stage for botrytis, which in moderate quantities is far from disastrous. Grapes with thicker skins, such as cabernet sauvignon, can resist rot; some winemakers think a little botrytis in their chardonnay adds to the flavor.

A serious case of botrytis is another matter, turning harvest into a nail-biter for some growers as they waited for sugar levels to rise: Would rot race through the grapes before they were ripe enough to pick?

“Once it starts, it rots by the hour,” said John Balletto of Balletto Vineyards in Santa Rosa. “It was so stressful. At one point we had 1,200 tons of chardonnay that was not harvested.”

Balletto, who sells most of his grapes to other wineries, got the last of his chardonnay picked by the end of October, bringing in 160 tons of grapes on one day. He estimates he lost about 25 percent of his chardonnay crop to botrytis — but at least his pinot noir, in hot demand this year, looks good.

Now that the chardonnay’s in, Balletto can relax a little. “When all this started happening, it went from a democracy to a dictatorship — ‘I’m in charge. Get it all done right now!”’ he said with a laugh.

Overall, Sonoma County Winegrape Commission president Nick Frey estimated 3 to 5 percent of the Sonoma County harvest may have been touched by botrytis this year. That could be a big deal for small growers, but overall it shouldn’t increase prices consumers pay. There’s already a grape glut from last year’s big harvest, and competition from producers outside the United States has kept prices low.

Botrytis also showed up in the Central Coast growing region near Santa Barbara, where harvest was also late.

At botrytis-loving Dolce, harvesters typically have different concerns. They worry that the fruit won’t get moldy enough, that the wrong kind of mold will develop, and that there won’t be the precise mix of damp followed by a balmy spell to allow sugar levels to rise.

This year, things went great. As harvest progressed, you could tell botrytis was in bloom as soon as you stepped into Dolce’s 20-acre vineyard and sniffed the distinctive, slightly sour smell of the fruit.

“This will kind of give you a graduate course on botrytis,” Hampson said on a recent visit, pulling berries off a cluster of semillon grapes, some green, some striped purple and some sporting gray fuzz.

The job of the botrytis is to evaporate water content and concentrate the sugars, acid and flavors. Dolce is mostly made with semillon grapes with a small percentage of sauvignon blanc.

When it comes time to press the grapes, clouds of dark spores fly into the air, smoke without fire.

For the first few years after Dolce was created, conditions were dry — no botrytis, no wine.

Then came the downpours of 1989. “If we had not gotten grapes in ‘89 we might have lost our nerve,” Hampson said.

Since then, they’ve tried to discover how best to propagate the mold. An interesting tactic is to see what works for strawberry growers, who try to do everything they can to stop botrytis and then do the opposite.