Courtesy of LangeTwins
Tim Hearden/Capital Press
NAPA, Calif. — The latest in a string of heat waves this summer has complicated a wine grape harvest that vintners had considered a post-drought return to normal.
Triple-digit afternoons in California’s prime wine-producing regions early this month left vintners scrambling to take protective measures to keep grapes from shriveling on the vines before crews could pick them.
In the Napa Valley, where temperatures reached as high as 107 degrees on Sept. 2, growers say fruit quality remains high because of winter rainfall and vineyard practices they employed during the growing season.
Heavy winter rains replenished reservoirs and brought soil moisture levels back to full capacity, said Heidi Soldinger, the Napa Valley Grapegrowers’ marketing and communications manager.
“Grapevines draw from these stores of moisture throughout the warmest summer months,” Soldinger said in an email. “In this way, stable soil moisture levels act as a natural heat buffer. Also, to date, air humidity levels remain high, even on the hottest days. The wet air, as with soil moisture, acts as a cooling element in the heat.”
Further, certain vineyard management practices helped growers protect their crop, Soldinger said. Techniques have included tunneling or leaf removal within the canopy to increase air flow and filter sunlight and using drip irrigation and sprinklers during major heat spikes, she said.
Growers have been watching their vineyards closely and managing them by hand to ensure quality and avoid fruit damage, she said.
“No growing season is ever the same and farmers are experts at quickly and thoughtfully responding to varying weather conditions,” she said.
A reprieve from the hot weather was expected this week, as Napa Valley temperatures were slated to top out in the low 80s this weekend, according to the National Weather Service. Long-range forecasts show valley highs averaging in the low to mid-80s for the remainder of September. Parts of the San Francisco Bay area even had a dusting of rain on Sept. 11.
Growers throughout California are in the midst of harvesting an anticipated 4 million ton wine grape crop, down slightly from last year’s production of 4.03 million tons, according to the National Agricultural Statistics Service.
The industry is getting back to normal after drought-related water shortages led to lighter crops in 2014 and 2015. Wine represents 60 percent of the state’s total grape crop.
While the first grapes for Napa Valley sparkling wine were picked Aug. 7, fog and cooler daytime temperatures slowed the pace of harvest in early August, but grapes started coming in at a steady pace once warmer days arrived, the Napa Valley Grapegrowers reported.
In some areas, hot days caused sugars to rapidly increase, sometimes faster than the grapes were maturing. Rapid increases in brix resulted in some grapes being picked as quickly as possible, while in other areas later varieties were irrigated to keep the grapes from dehydrating, according to a report from the Sonoma County Winegrowers.
The harvest comes as winery revenues are at an all-time high. U.S. wine exports, 90 percent of which are from California, reached a record $1.62 billion in winery revenues in 2016 despite a nearly 10 percent drop in volume, according to the San Francisco-based Wine Institute.
California wine exports have grown 78 percent by value in the last decade even as volume has lagged because of various factors, including short production during the drought and trade barriers in some nations.