North Coast heat spike kicks grape harvest into high gear

A month after the 2017 grape harvest kicked off, Mother Nature threw growers a curve ball, spiking temperatures well past the 100-degree mark across the North Coast and sending crews scrambling to protect the fruit.

As harvest kicked into high gear, winemakers made strategic decisions, speeding up their picks or irrigating their vines to get through the heat spell until the grapes have sufficiently ripened.

After a rainy spring and a summer of relatively cool, often foggy days led to fears of patchy outbreaks of botrytis and powdery mildew, wineries shifted their attention this week to preparing for the heat wave. An excessive heat warning has been issued for Sonoma County through Monday, and the wineries’ challenge has been compounded by night-time temperatures that have remained in the mid-70s - hardly the typical cool nights that help grapes retain their acidity and develop their tannins.

“To get through this heat wave, you are seeing growers giving the vines a little water,” said Karissa Kruse, president of the Sonoma County Winegrowers trade group. “You don’t want grapes that are plump with water.”

Most local wineries are finishing up their harvest for sparkling wine, picked earliest, with the last picks for those grapes to be completed by next week, Kruse said. Vintners already have started picking certain varieties for still wine - chardonnay, pinot noir, sauvignon blanc - while other later-harvest fruit such as cabernet sauvignon and zinfandel are still weeks away from optimum ripening.

Smoke from the Trinity County and other Northern California fires should not pose a problem for the local crop as grapes are more susceptible to smoke taint in the early summer than at this point in the growing season.

At the Bow Tie Vineyard in the Russian River Valley, crews early Friday picked about ?25 tons of chardonnay grapes that will go into bottles for J Vineyards & Winery and currently sell for $45 retail. They finished before 8 a.m.

Blair Mitchell, coastal ranch manager for E&J Gallo Winery, said he worked with J winemaker Nicole Hitchcock to ensure that any grapes that could be susceptible to the heat damage would be off the vine before they would start to shrivel, or “raisin.”

“All the J vineyards are really not going to hit a problem because we started picking early enough and have just continued to plan out,” Mitchell said. “Everything that really has a risk of not making it through the heat spike has already been picked and put away, or has a plan to be picked by Monday or Tuesday at the latest.”

He credited good maintenance on the leafy canopies of the vines, which balanced creating enough space for air flow to prevent most outbreaks of powdery mildew with sufficient cover so the grapes won’t burn in the late afternoon sun.

“I think a lot of this has been in the lead-up to where we are now. It’s been appropriately managing the canopies, which has been such a big thing this season with (winter rains),” Hitchcock said.

Alison Crowe, director of winemaking for Napa-based Plata Wine Partners, emphasized the importance of all the vine maintenance leading up to harvest, beginning when they are pruned in January.

“With super-aggressive leaf pulling, the grapes will be fried,” said Crowe, who started her harvest on Thursday with a pick of pinot noir grapes in the Carneros region of Napa County. “This is just Mother Nature hitting the gas.”

The yields so far appear to be about average, Kruse said, with fluctuations depending on the variety. For instance, the cabernet sauvignon yield appears to be lighter than last year, she said.

“No one is saying this is going to be a record year,” Kruse said.

The North Coast has a 10-year average yield of 461,648 tons. The harvest last year generated a cash value of almost ?$1.5 billion, with a record of $717 million in Napa County and $581 million in Sonoma County.

You can reach Staff Writer Bill Swindell at 707-521-5223 or

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