Sonoma Valley vintners rush to finish harvest before rains

Facing one of the latest harvests in the past decade, Sonoma Valley farmers hoped Mother Nature would keep the grapevines dry until the late-harvested merlot, Cabernet Franc, Petit Verdot, Syrah and Malbec grapes could ripen.

Nearly half an inch of rainfall fell on some parts of Sonoma Valley on Sunday, pushing local vineyards into a state of anxiety as early rains — and the accompanying threat of mold and disease — threatened to imperil months of agricultural effort.

“There is worry across the industry of fruit ripening, especially the bigger reds,” said Taylor Serres, an operator of Serres Ranch in Sonoma. “We tried to get all of our Zinfandel off and we got majority of it off. We still have a little bit out there, which I hope we'll be able to get off, but I'm not holding my breath.”

As grapes near the end of their growing season, farmers are unable to use fungicides to protect them from mold and diseases, such as botrytis. Yet, early rains can create the perfect environment for mold to flourish.

“If you do get mold of any kind, the winery has the right, and most likely will, reject the fruit because it's not the standard,” Serres said. “I feel for everyone who has fruit left on the vine.”

The ripening of grapes to a desired Brix level — measuring the grapes’ sugar content — is key to the taste and fermentation in winemaking later on. This is typically not an issue for the Eden of Sonoma Valley, owner Dane Cellars winery Bart Hansen said.

But the moderate temperatures this summer caused grapes to ripen slower than in the past decade, pitting farmers’ expected harvest dates against the beginning of California’s rainy season, Serres said.

“The fruit that we're bringing in, it has gotten to the our desired Brix level, so we’re fortunate for that,” Serres said. “We just wanted to leave it on just a little bit longer to see if we can develop a little bit more of those flavors.”

The grape harvest after the rain Sunday has affected small wineries, like Hansen’s Dane Cellars which sources their grapes from a variety of Sonoma Valley vineyards.

Hansen has worked at vineyards and wineries across the Valley since 1986, and he said he’s usually never stressed due to the friendly climate of Sonoma Valley.

But the rain Sunday forced him to rent out space for grapes that he had to quickly process before mold could threaten the crop.

“I felt like the grapes were gonna get through the rain without problem. Now, that was the eighth of an inch or something that (weather forecasters) were threatening,” Hansen said. “When it just continued to rain and continue to rain and continue to rain. Then it's almost punishing.”

In spite of the less-than-ideal harvest weather, Hansen and Serres expressed optimism that wind and a few days of warm weather would prevent mold in most crops.

Still, a late-harvest rain affects some types of wine worse than others.

“I was fortunate because I didn't have any white grapes still out there, no Chardonnay, no sauvignon blanc,” Hansen said. “The other grape varieties that I hanging out there do fine through some rain.”

Last weekend’s rain showed both the challenges and excitement that mutually exist in farming, which Serres said is “not for the feint of heart.” Serres Ranch picked more grapes from their property Tuesday morning, and Serres said the harvest will continue through at least Nov. 10.

Despite the inclement weather, both Serres and Hansen agree this year’s vintage will be one to celebrate — even with a little rain on their parade.

“Mother Nature is always in control of the weather,” Serres said. “You can drive yourself crazy trying to control it, but there is no way. She has the last laugh always.”

Contact Chase Hunter at chase.hunter@sonomanews.com and follow @Chase_HunterB on Twitter.

Correction: A previous version of this article incorrectly spelled the last name of Bart Hansen.