Not-so-Merry May in California Vineyards

Grapegrowers grateful for every scattered shower, even during bloom

by Jane Firstenfeld
This image from Concannon Vineyard in the Livermore Valley illustrates vine growth between March (left) and May.
San Rafael, Calif.—As year five of the California drought gets under way, the wine industry welcomes the smallest drop of precipitation.

“The only rain Napa has had in the past month” was a mere sprinkle, said Jennifer Kopp Putnam, executive director of the Napa Valley Grapegrowers. “We are almost through bloom. It was an early bud break and an early but extended bloom this year. In some parts of the county, growers have berries, but many sites are still in set.”

Just north of Napa, Lake County reported a smattering more rainfall. Jonathan Walters of Brassfield Estate Winery, president of the Lake County Winegrape Commission, said, “We have had a couple of cells that have produced some rain and even hail in the higher elevations. Most of the rain has accrued in the higher elevations across the county.

“The month of May has probably pushed back harvest due to the lower temperatures. The lower temperatures caused a longer than normal bloom period where rain could have affected some set across the county,” he said, adding that that he wouldn’t expect much resulting crop loss. “Bloom is about to be over for most everyone, with this year’s crop being set.”

In adjacent Mendocino County, “It’s showering here in Redwood Valley as we speak,” said Martha Barra, owner of Barra of Mendocino Winery, on June 1.

“It is a light rain, so it is not going to amount to much. It did rain about 1 inch during May. We welcomed the small amount of rain because the vines needed a drink,” she said. “The rain and the warmer than usual weather did cause the shoots to grow quickly, to the extent that we had to bring in a contract crew from Sonoma County to perform shoot removal so we could accomplish that task in a timely manner.”

Even a little rain can increase vineyard labor. Farming organically, Barra said, “We had already turned under the cover crops when the rains came. Now we are finding new growth of mustard under the vines, and our weed-eating crew is doing the repetitious work of keeping the grasses down around the reservoirs and fencerows.”

“With the warm weather, and no real cold weather during the winter to kill off pests, we have had an unusually high count of leafhoppers. We are on our second spraying of Stylet oil,” Barra reported.

The vines are in good shape, though. Vineyard foreman Roberto Gonzales reported: “We are ahead of schedule for berry set by about two weeks.”

“Chardonnay and Pinot Noir are set, and grape berries are well formed. The Cabernet is in full bloom, and in our appellation, the Petite Sirah is as well. Cabernet Sauvignon appears to have the potential of setting the heaviest crop,” Barra said. “The berries aren’t touching yet, but the berries are definitely formed.”

Moving south
Similar conditions have prevailed in the vast Central Coast appellation. In the Santa Cruz Mountains, “May has been a foggy, cool month, more like June gloom than May flowers. The Santa Cruz Mountains West have had drizzly morning fog that sometimes reaches the summit and spills over to our eastern side,” said Prudy Foxx, local viticulture expert and board member of the Santa Cruz Mountains Winegrowers Association (SCMWA). 

“Almost every vineyard has reported cool temperatures showing in the vines with the signature yellows that lighten the leaves when spring temperatures drop. Most sites experienced at least one somewhat significant rain, with some gauges filling as much as one-half inch. Most sites received significantly less water, but the ongoing drizzle lasted most of one day,” Foxx reported.

“There was one other day with what might be called rain. Again, the rain gauges were variable depending on where the vineyard lay in our diverse region. Perhaps one-eighth inch at best,” she said.

“The biggest threat has been the moisture during bloom. Fortunately most sites dry off by afternoon, and the fruit has been able to set despite the heavy morning dews and foggy moisture-laden breeze. Most vines have set fruit and are looking healthy and happy.”

Nevertheless, a little untimely damp can engender problems in vineyards. “There is some Botrytis in isolated vineyards where the wet pressure rotted off flower clusters before they could set—or where the spray program or heavy canopy did not protect the delicate flowers. Pinot Noir, as always, is the most sensitive to these conditions, and set might be down with this fruit if growers were not able to protect the flowers or the pressure due to the timing of the wet days was too great on their site,” Foxx said.

Reporting from neighboring Monterey County, Matt Shea, vineyard manager of Bernardus Vineyards and Winery said, “We have had a colder than average last few months with relatively little rainfall. May only had two rainfall days totaling less than a half an inch. Any degree-day accumulation advancing the season from our warmer than average start was averaged out, and we are now about at average accumulation for June 1,” Shea said. “While the vines appreciate any drop of rain, the timing did occur during a long, drawn-out flowering. I expect to see a small drop in yield due to a high number of stuck caps.

“Our cooler sites are just now finishing flowering, and have lagged behind during these cool weeks. Our warmer sites are through flowering but are moving slowly. We have been more aggressive in our shoot thinning—and earlier in our leaf pulling—in order to keep an open fruit zone for mildew control and to channel available resources only to our selected fruiting shoots,” he said.

“The vines have already responded to the relatively warmer weather over last weekend,” and Shea added hopefully that he expected to see some strong growth.

Reporting from the landlocked Livermore Valley Winegrowers Association, John Concannon of Concannon Vineyard said, “The Livermore Valley continues to be very dry with only 0.47 inches of rainfall in May. Although with the average high at 77° F and average low at 50° F, the cooler weather is allowing the vines to grow very evenly to maturity. I continue to see a slightly lower yield this year, but the vines do not appear to be stressed at this time.”

Concannon said that although growth is slower due to the cooler weather, it “still remains about two weeks ahead of last year.”

And the good news: “Overall quality is still looking outstanding,” according to Concannon.

Grim forecast continues
Still, the prognosis remains dire for California agriculture, according to the California Water Blog’s June 2 edition, published by the University of California Davis’ Center for Watershed Sciences.

“The drought is expected to be worse for California’s agricultural economy this year because of reduced water availability, according to our preliminary estimates released today.

“The study estimates farmers will have 2.7 million acre-feet less surface water than they would in a normal water year—about a 33% loss of water supply, on average. The impacts are concentrated mostly in the San Joaquin Valley and are not evenly distributed. Individual farmers will face losses of between zero and 100%.

“Economically, the drought seems on track to reduce crop, dairy and livestock revenues by $1.2 billion this year. Pumping costs are expected to reach nearly $600 million. Overall, the drought is estimated to cause direct costs of $1.8 billion—about 4% of California’s $45 billion agricultural economy.”

Posted on 06.03.2015 - 08:39:06 PST
This is a biased article. The author is looking for a grape growing crisis that doesn't exist. Vineyards need little water compared with other crops. Perhaps she should write about Central Valley almond farmers.