Central Coast Vineyards Cope With Drought
Advisors say to adjust for smaller canopies and lower yields
Michael Anderson, state climatologist with the California Department of Water Resources, quoted a letter from National Resources Conservation Service district conservationist Rich Casale, who minced no words: “The previous historic dry records have been completely demolished, being shattered by very large deficit numbers which are staggering with complications for the future health and wellbeing of the California economy and California ag….The news thus far this season for water is dismal at best. It would require biblical, epic-type rainfall across California to mitigate the damage.…California water supply is heading for severe restrictions…a truly historic, unprecedented drought.”
Following the driest year on record, what can grapegrowers do if 2014 continues the pattern?
Fritz Westover, technical program manager for the Vineyard Team (formerly Central Coast Vineyard Team) in Atascadero, Calif., told Wines & Vines how members are coping.
“Some, however not all, growers have reported a reduction in crop and canopy size due to the dry conditions over the past two years,” he said. “With little rainfall occurring in the area, it is safe to presume that the root systems of vines are ever-decreasing in size, and root activity is mostly limited to the zone of wetness in irrigated vineyards.
“Attentive growers will likely adjust down their crop level when dormant pruning this winter,” Westover said. “I had a long discussion with the president of one of the leading vineyard-management companies on the Central Coast, which is taking this approach to avoid further stress on vines in 2014.”
Westover’s previous employment in ag extension in Texas gives him special expertise in dealing with drought.
“While I worked with the Texas A&M extension service in 2011, we experienced a severe drought that resulted in smaller canopy size and smaller average cluster weights around the state,” he recalled.
“Even with the vines’ own compensation mechanisms in place, it was a full two years before some of those vineyards recovered to normal canopy and crop levels. Some are still recovering. Vines on low-vigor rootstocks seemed to be hit the worst in that example. I suspect we could see a similar scenario in some areas of the Central Coast.”
No cover story
Those dreary brown vineyards aren’t yet brightened by traditional cover crops. At the moment, this is not a problem, but it could become one.
“In addition to the effects on vines, we are also seeing that cover crop establishment is a big challenge in the absence of winter rains,” Westover said. “Having less cover crop may be a good tradeoff for water conservation, but if we eventually do get hit with rain events, the infiltration will be less without the cover, and the soil erosion risk also goes up.”
The arid winter season has also been a warm one. Many California growers have traditionally used sprinklers to combat frost damage, a highly visible practice that tends to enrage water-conserving neighbors. That’s not yet been a problem this season.
“It is too early to know how much irrigation will be used to combat frost this coming spring,” Westover said. “If the grower has enough water, and uses it for this purpose, he will also benefit from the uniform moisture distribution it provides to the vineyard. (But) not all growers have the capacity to use water in this way.”
Where will water come from?
The majority of the vineyards in the Central Coast rely on irrigation for most of the growing season,” according to Westover. “The recent drought has sparked renewed interest in the topic of dry farming, or moving closer to dry farming practices where possible.
“The majority of water used in Central Coast vineyards is ground water. The Paso Robles groundwater basin is likely the most frequently discussed water source in the media these days, where new emergency ordinances have put a halt on new vineyard plantings,” Westover said.
Jeff Pomo, vineyard manager for Constellation Wines in California’s Monterey County, commented, “100% of our vineyards rely on drip irrigation. The source of our irrigation water is groundwater.”
While local or statewide water-use restrictions are not yet in place, they are quite likely on the drawing board. “If there aren’t any restrictions on how much water we can use, we plan to deficit irrigate like we always do: Irrigating to about 70% of what the vine is demanding,” Pomo said.
“If we start dropping that percentage, then we’re going to see a decrease in yields and a reduction in the overall vine shoot growth. This reduced shoot growth could negatively affect next year’s yields as well, because the fruit for next year is in the undeveloped buds on this year’s shoot growth,” he noted.
Given Constellation’s multiple brands and the vast acreage needed to support production of more than 16 million cases annually, “On average we irrigate about 1.1 acre feet of water per ac re per year (about 360,000 gallons per acre per year),” he specified.
“We have had to drip irrigate most of this winter because of how dry it’s been. That is not normal. We normally stop irrigating the beginning of November and don’t start again until February or March.
“We don’t have any overhead sprinklers to irrigate the cover crop, so the cover crop hasn’t grown. One of the biggest concerns for us is that the water we use to irrigate is high in salts. Throughout the growing season, while we’re frequently irrigating, the salts can build up in the top layer of soil. Salt concentration in your soil can negatively affect overall plant growth.
“We rely on our winter rainfall to flush the root zone of those salts that built up from the prior year’s irrigations. Last year’s winter was below average as well, and we saw stunted growth in some of our less-tolerant rootstock blocks. A second year in a row of low rainfall is going to cause an even greater concentration of salts in the soil, and even poorer growth than last year.
A scary season
Pomo added a side note: “It has also been unseasonably warm. This is causing the vines to want to push earlier than normal. We expect to see bud break two to three weeks earlier than normal this year. That’s scary, because that means the window for getting frost damage is just that much greater now.”
With the last measurable precipitation being 0.19 inch in December 2012, and a scant sprinkle in November 2013, Monterey County vineyards are “dusty in the middle of January,” said Andy Mitchell, director of vineyard operations at 400,000-case Hahn Family Wines. “Last year was bad, but this year is much worse.”
Matt Shea, vineyard manager for 50,000-case Bernardus Vineyards & Winery in Carmel Valley, and a board member of the Monterey County Vintners and Growers Association, summarized information from the 65 member vineyards: “The overall average percentage for most of our reporting sites is 9% to 11%; however, the percent total for water year is only at 3% to 4%.” Most of these are 100% irrigated.
He complimented association members: “Our vineyards are very resourceful and are no strangers to dry weather conditions. They capture rainfall, have wells and river pumps.
Hahn’s vineyards are 100% irrigated with groundwater from the Salinas River and Arroyo Seco (“dry riverbed”) River watershed aquifers, Mitchell said. Hahn will continue to monitor and judiciously use its water resources to ensure vine health, he said. “Stressed vines do not hold up as well as vines that are not….Until the threat of cold weather is over, which really varies from one region to the next, vineyard soil moisture levels should be maintained as high as possible.”
Shea emphasized too: “Most have been irrigating on and off all winter. When possible, it’s extremely important to keep the root zone from completely drying out, and provide the soil and plant with what would be a “normal” precipitation amount.
Mitchell noted yet another cost of the drought: “Extremely high utility bills for what should be a slow time of year for pumps and irrigators. Cover crops are nearly non-existent in blocks that are drip irrigated.”
Santa skipped Santas Cruz and Barbara
The Santa Cruz Mountains normally get much more rain than other Central Coast regions, but, said Mary Lindsey, who handles marketing and sales for 300-case Muns Vineyard in Los Gatos, Calif., and serves as president of the Viticulture Association of the Santa Cruz Mountains: “We had almost the full season’s normal precipitation in two months: November and December 2012. Enough to charge the soil through the 2013 growing season.” After a few inches in the spring of 2013, and a couple of inches late in the year, “So far this year: Zilch….Everyone is hurting for rain.”
The major sources for growers who irrigate in the AVA’s many microclimates are wells, Lindsey said, although some have dried up.
“The lack of water is impacting cover crops,” she said. “It is so dry there is none to speak of. Usually the cover crop is greening by now. Those who planted seed at the end of last year aren’t seeing any growth. This could impact soil health, dust mitigation and erosion control.
“If you're not on top of your gopher population, they’re moving into the vine root zones where they can find food and more moisture.
It's not just the lack of rain, but also the spring-like temperatures right now that are of concern. Daffodils are blooming two months earlier than usual, and if this weather keeps up, there is a concern that bud break will be very early: Soon,” she warned.
“Some of us have a concern about what a foreshortened dormancy might mean on vine health. And given the healthy crop load over the past two seasons, it would not be surprising if this year’s crop load is reduced.”
Farther south in Santa Barbara County, Wes Hagen, vineyard manager/winemaker at Lompoc’s 1,700-case Clos Pepe, reported only 3 inches of rain in the past 12 months. His vineyards—and, he reckoned, most others in the county—are irrigated. Clos Pepe uses ground water from the Santa Ynez River.
Hagen offered recommendations to fellow growers: “Run water sets at night to maximize efficiency, 100% drip emitter irrigation….Minimize all sprinkler activity.
“Be very careful just to replace evapotranspiration (ETO) and not overwater, apply materials to flush salts from the root zone to make water more available to drought-impacted ro ots with salt accumulation,” he advised.
Is there any help?
Lindsey shared an excerpt from a letter she received from the USDA Natural Resources Conservation Service (NRCS), offering to “Help you with your drought concerns by making site-specific recommendations and/or by creating a plan that will allow you to continue and/or adapt your operation even in the most severe conditions. NRCS provides information, technical and financial assistance with irrigation-system improvements and water management; water storage; retention of soil moisture; selection of drought resistant plants; runoff recovery; as well as many other practices that can help to mitigate the effects of drought."
Westover commented, “It may be too early to say how drought has affected vineyards to date. A study by UC Cooperative Extension is showing that salt levels have accumulated in vineyard soils over the years, and I imagine that this problem will be exacerbated by the drought.”
“Winter is usually the time when salts are flushed from soils with rainwater. There seems to be a trend for vines on vigorous rootstocks to be holding up a bit better,” Westover said. “I have observed in more than one vineyard that canopy size of vines growing on 1103 Paulson rootstock were noticeably larger than those on the same variety on 101-14 Mgt. This is strictly observational, but it matches trends observed during the Texas drought in 2011.
“The Vineyard Team has been positioning itself to provide educational and cost-share programs and hands-on vineyard demonstrations to assist water monitoring and irrigation decisions by growers. Our team will initiate irrigation monitoring demonstrations in three Central Coast vineyards in 2014 to showcase technologies for monitoring soil and plant moisture.
“The demonstrations will take place over the next two years, in which time we will also hold educational tailgate meetings at the vineyards, hosting experts to speak on irrigation monitoring technologies. Our team is actively pursuing partnerships with Pacific Gas & Electric and the Fresno Center for Irrigation Technology to provide cost-share and technical support for growers to install technologies such as flow meters and soil-moisture sensors in the vineyard. There is a wealth of good information out there to help growers and our goal is to bring these concepts closer to the grower and increase adoption of their use.”