The 2010 roller-coaster season will go down in the books as one wild ride for Napa Valley wine grape growers.
“People who’ve been in the business for 30 years or more say they’ve never seen anything like it,” says vineyard consultant Garrett Buckland, a partner in Premiere Viticultural Services, Napa, Calif., which manages vineyards for clients mostly in Napa County.
“We started with a cool spring and the weather continued cool, with temperatures never getting much above 90 degrees,” he says. “In terms of accumulated degree-days, we were about 20 percent below normal all season.
(Accumulated degree days from April 1 through October 30 at the nearest reporting station, Oakville, totaled 2,781 this year, down from 3,101 in 2009. This 2010 figure compares to the next lowest total accumulated degree days for the same period during the previous 10 years of 2,882 in 2008 and the highest total of 3,226 accumulated degree days in 2003.)
“Then, we had a tremendous heat spike, with 114-degree temperatures and humidity in the single digits for several days in a row Aug. 23-25. Another heat wave hit around 10 days later.”
For most growers, the topsy-turvy weather set back the start of harvest about a week or more to the first or second week of September.
More was yet to come before the last grapes were picked the first week of November — a series of hefty rains in the third and fourth weeks of October, when some vineyards received as much as 5.5 inches in two days. Prior to that, forecasts for wet weather sent harvest crews scrambling to get grapes off the vines.
“Working nearly round-the-clock, they picked like crazy, harvesting nearly half the fruit in Napa County in the seven to 10 days before the heaviest rains started Oct. 22,” says Buckland.
Despite all that, and including damage to about 5 percent to 10 percent of the grapes in the heat wave, yields in most cases were about average, he notes.
“We had some significant yield reductions in several varieties. In some vineyards, we lost 10 percent to 20 percent of our Sauvignon Blanc and Merlot, but still ended up with about average tonnage. A lot of our growers made their target yields — which is fantastic in a year like this.”
Napa Valley growers faring the best this past season we’re those who stayed calm. “They didn’t overreact,” Buckland says. “This year proved that staying on top of the situation, remaining flexible and following good viticultural practices pays off.”
For example, in dealing with the cooler temperatures, that meant not over-thinning or removing too many leaves from the vines.
“Some growers stripped away too much of the canopy and lost 20 percent to 30 percent of their crop,” he says. “Growers who planned ahead and saved some water earlier in the season to keep roots fresh later, or who gave their vines big drinks of water less frequently rather than sticking to a strict irrigation schedule, avoided some of the problems that others experienced during the heat wave.”
Close cooperation between Napa Valley’s grape producers and winemakers also played a critical role in dealing with this year’s fluctuating weather.
“The wineries gave strong support to the growers,” Buckland says. “For example, if there was heat-damaged fruit, the people buying the grapes let the growers pick around the poor grapes. No one was pointing fingers because of any weather-related problems.”
For growers who adapted their management to meet the weather challenges, Mother Nature rewarded them and their buyers with an exceptional crop.
Take Cabernet Sauvignon, for example. These grapes were able to make the most of a very long season and very early maturity, Buckland says. Even damage from the heat wave, which hit at the tail end of veraison, occurred after all of the components responsible for good structure, color and flavor of the berry had developed.
“If the heat waves had been any earlier, quality would have suffered greatly, he says.
“Overall, the wine quality of the Cabernet is outstanding. For many wineries, it was as if you could marry the best vintage of Bordeaux with the best that California has to offer. For many this will be the vintage of the decade.”