Lee Martinelli Jr.’s workday began about 3 a.m. Friday after three hours of sleep, as he led a crew of workers back into his family’s Russian River Valley vineyards along River Road.
Like most grape growers, Martinelli is bringing in the 2017 harvest mostly at night, when cooler temperatures favor both workers and the fragile grapes they are clipping from vines covering nearly 60,000 acres in Sonoma County.
Overheated grapes can break open and start to ferment on their own, Martinelli said Thursday, taking a break at the 100-acre vineyard across the road from the landmark Martinelli Winery.
Thursday’s ultralight rain wasn’t troubling, the fourth-generation vineyardist said. In fact, it afforded growers a respite after the four-day heat wave over Labor Day weekend threw the harvest into high gear.
Grapes lost some weight during the streak of triple-digit days that started Aug. 31, a loss for owners who get paid by the ton for their crop once a year.
“That’s farming,” said Martinelli, 52, a lean, silver-haired man in jeans and a plaid shirt.
Every year is a waltz with the weather for the men and women cultivating Sonoma County’s $581 million wine grape crop, which accounted for more than one-third of the North Coast’s $1.5 billion crop last year.
“What I worry about is the next few days,” Martinelli said. If he had an app that could dial up the weather, he would order breezy days with temperatures in the 75- to 85-degree range, ideal for drying out damp grapes.
If the berries stay wet and the sun comes out, the combination of heat, moisture and sugar in the grapes can trigger botrytis, also known as bunch rot, a fungus that can spread quickly and wreak havoc.
Rhonda Smith, a viticulture farm advisor with UC Cooperative Extension in Sonoma County, said botrytis infections are “ubiquitous” and ever present. The real concern, she said, is whether high humidity and mild temperatures persist long enough to allow the fungus to trigger “disease onset.”
Botrytis often occurs on one or more grapes in a vine cluster, she said. Disease onset becomes severe when, for example, there are 50 berries in a cluster damaged by the fungus. Smith said she’s been out to several ranches this season but seen few clusters completely diseased.
The warm, dry weather that curbs rot is not expected until Sunday, she said.
Charles Bell, a National Weather Service meteorologist, said the weak atmospheric system that brought Thursday’s light rain — generally a few hundredths of an inch — would likely clear Friday. Temperatures are expected to warm into the 80s Saturday and the mid-80s to mid-90s Sunday.
Martinelli said he hoped to take Sunday off after about three straight weeks of picking in the family’s 450 vineyard acres from Forestville to Cazadero.
His work schedule has been brutal, sandwiched around a pair of separate, three-hour periods of sleep every 24 hours. Picking starts in the wee hours and runs until about noon, followed by a siesta before resuming work in late afternoon to plot the next day’s harvest.
Martinelli said he sees less of his wife, Pam, and their daughter, Maddy Lu, 14, during harvest and his social life is nil.