Posts Tagged: Grapes
Wine grape growers in California and elsewhere face increasing labor costs and severe labor shortages, making it difficult to manage and harvest a vineyard while maintaining profitability. Growers are increasingly turning to machines for pruning, canopy management and harvesting, but how well these practices are executed can substantially affect yield and quality. A new review by researchers at the University of California, Davis, published in the journal Catalyst, provides guidelines for growers to make the best use of machines.
“Wine grape laborers have been virtually nonexistent. People don't want to work in vineyards anymore because it's remote, tough work,” said Kaan Kurtural, UC Davis professor of viticulture andenology andUC Cooperative Extension specialist. “There is now machinery available to do everything without touching a vineyard.”
Kurtural has designed a “touchless” experimental vineyard at the UC Davis Oakville Station to help growers understand how machines can help them cope with the labor shortage. While machines reduce the need for seasonal manual labor, they do not eliminate it. The degree of labor reduction depends on growing region, grapevine type and the number of practices growers mechanize.
The review provides guidance on using machines for winter pruning, canopy management and harvesting as well as how to design a grape vineyard for machines before planting. Videos showing the operation of different types of machinery and practices can also be found in the review.
Economic savings, quality grapes
About 90% of the wine grapes crushed in the U.S. are mechanically harvested. Previous studies have found about a 50% savings in labor costs from using machines to harvest instead of hand harvesting.
“Using more mechanization in a vineyard beyond just harvesting can also reduce labor costs without affecting grape quality.” Kurtural said.
Mechanical pruning, for example, can save between 60% to 80% of labor operation costs per acre compared to manual pruning alone. One experiment in the San Joaquin Valley, where more than 50% of California's wine grapes are grown, also showed using mechanical canopy management machines to manage merlot grapes resulted in twice the amount of color. The more color, or higher anthocyanin concentrations, the better the quality. It can significantly improve returns from vineyards in California's heartland.
Kurtural said there are machines available to manage canopies, including machines for leaf removal, shoot thinning and trunk suckering. Kurtural noted that the machines are American made, developed by researchers at the University of Arkansas and commercialized by manufacturers in Fresno and Woodland, California.
The review was co-authored by Matthew Fidelibus, UC Cooperative Extension viticulture specialist at UC Davis, based at UC Kearney Agricultural Research and Extension Center. Financial support for the research came from the American Vineyard Foundation and Bronco Wine Company.
A welcome sign of spring each year for grape producers is budbreak, the moment when tiny buds on the vine start to swell and green leaves appear. Budbreak varies by region, variety and even vineyard topography, but in Sonoma County, unseasonably warm weather caused buds to burst early, reported Bill Swindell in the Press-Democrat.
“Perhaps it's the new normal,” said Jen Walsh, the winemaker at La Crema Winery in the Russian River Valley, commenting about long-term change due to global warming.
The Carneros region that borders San Pablo Bay is typically the first wine appellation to experience bud shoots on grapevines, given its milder climate, said Rhonda Smith, UC Cooperative Extension viticulture advisor in Sonoma County. In addition, hillside vineyard areas in the county with south- and west-facing slopes also usually are on the early side because of their longer sun exposure.
There is a downside to early budbreak. The vines are susceptible longer to a potential spring frost, which could harm opening buds and young shoots.
Below are recent tweets heralding the 2020 budbreak around California.
Wine grape growers in the San Joaquin Valley who want to switch from hand pruning to mechanical pruning won't have to replant their vineyards to accommodate machinery, according to a new study published in HortTechnology by University of California Cooperative Extension researchers. Instead, growers can retrain the vines to make the transition, without losing fruit yield or quality.
Mechanical pruning reduced labor costs by 90%, resulted in increased grape yields and had no impact on the grape berry's anthocyanin content. That's welcome news for growers because the cost of re-establishing a vineyard in the region is roughly $15,600 per acre.
“We found that growers do not have to plant a new vineyard to mechanize their operations,” said Kaan Kurtural, UC Cooperative Extension specialist in the UC Davis Department of Viticulture and Enology. “We have proven beyond a doubt that an older vineyard can be converted to mechanization. There is no loss in yield during conversion and post-conversion yield is better and fruit quality is equivalent to or better than hand-managed vines. The economies of scale are evident in the savings per acre and per vine as depicted in the balance sheet provided with the newly published paper.”
The research was conducted in an 8-acre portion of a 53-acre, 20-year-old Merlot vineyard in Madera County. After completion of the research project, the grower converted the rest of the 53-acre vineyard to single high-wire sprawling system. Many other wine grape growers have followed suit.
The Wine Group, which manages 13,000 acres of vineyards across Central California, is establishing new vineyards and converting old vineyards for mechanical pruning and suckering, said vineyard manager Nick Davis. Davis, who works closely with Kurtural and the UCCE viticulture advisor in Fresno County, George Zhuang, said the company greatly values the UC Cooperative Extension research that is guiding the changes.
“I think extensionists are undervalued,” Davis said. “We lean on them for applied research, which has been wonderful. They offer us what we can't provide ourselves.”
More than half of all California wine grapes are grown in the San Joaquin Valley. Worker shortages, rising labor costs, low returns and occasional droughts are driving wine grape growers to seek innovative ways to sustain their businesses.
“To help growers maintain the profitability of their vineyards, we're studying the use of machines to reduce the number of people needed to perform tasks like pruning,” Zhuang said.
“Because the canopy architecture and yield characteristics of mechanically pruned vines are different from vines that are hand-pruned, the water and fertilizer requirements for the mechanically pruned vines can be quite different. So we are studying the yield and fruit quality of grapes produced on different rootstocks in mechanical pruning systems in the San Joaquin Valley,” Zhuang said.
The Madera field study was conducted for three consecutive seasons in the hot climate conditions typical of the San Joaquin Valley. In this area, traditional vineyards are head-trained to a 38-inch-tall trunk above the vineyard floor and two eight-node canes are laid on a catch wire in opposite directions and two eight-node canes are attached to a 66-inch high catch wire. Although this traditional training system can work for mechanical harvesting, it doesn't accommodate mechanical dormant pruning and shoot removal with limited success in other mechanical canopy management operations.
To accommodate mechanical pruning and shoot removal, the vines were converted to a bilateral cordon-trained, spur-pruned California sprawl training system, or to a bilateral cordon-trained, mechanically box-pruned single high-wire sprawling system.
The latter option proved to be the most successful system for mechanical pruning in the San Joaquin Valley.
On Feb. 19, San Joaquin Valley grape growers are invited to discuss the latest UC research on mechanical pruning, trunk disease and rootstocks with UC Cooperative Extension advisors and specialists in Fresno. Growers will also get to observe a field demonstration of grapevines being mechanically pruned.
“We have been hearing from California grape growers that they are having a hard time finding enough workers to maintain their vineyards and increasing labor cost starts challenging grape-farming economic sustainability so we are studying the use of machines to reduce the number of people needed to perform tasks such as pruning,” said George Zhuang, UC Cooperative Extension viticulture advisor for Fresno County.
Gabriel Torres, UC Cooperative Extension viticulture advisor for Tulare and Kings counties, will discuss plant diseases that may result from trunk injuries and pruning wounds from the machinery.
Karl Lund, UC Cooperative Extension viticulture advisor for Mariposa, Merced and Madera counties, will discuss how to select rootstock for a vineyard that will be mechanically managed.
“Because the canopy architecture and yield characteristics from mechanically pruned vines are much different from hand-pruned vines, the water and fertilizer requirements of mechanically pruned vines can be quite different,” Zhuang said. “Therefore, performance of different rootstocks under mechanical pruning system is critical to achieve both yield and fruit quality targets of grape production in the San Joaquin Valley.”
Kaan Kurtural, UC Cooperative Extension viticulture specialist in the UC Davis Department of Viticulture and Enology, will go over the basic principles of mechanical pruning of wine grape vines.
From 8 a.m. to 10:30 a.m., UC Cooperative Extension advisors and specialists will meet with growers in a Golden State Vintners vineyard at 7409 W Central Ave in Fresno.
“We will discuss current grape issues and the future of viticulture in the valley,” Zhuang said.
The meeting, which is being co-hosted by UC Cooperative Extension and San Joaquin Valley Winegrowers Association, is free. For more information, contact Zhuang at firstname.lastname@example.org or (559) 241-7506.
Will machines replace the romance of the hand-cultivated wine grape vineyard? A “touchless” vineyard was among the latest research on labor shortages, weeds and pest management by UC Cooperative Extension scientists discussed at Grape Day at the UC Davis Oakville Station, located in the epicenter of California wine country, on June 6.
About 200 wine grape growers, vineyard consultants and other industry people attended to learn about the latest UC Cooperative Extension research. Vineyard managers from boutique wineries such as Fork in the Road to Pine Ridge Vineyards to the Fortune 500 wine company Constellation Brands gathered at the research station's experimental vineyard. Several vineyard equipment representatives brought their machines to the field to demonstrate their weeding, pruning and canopy management capabilities.
Addressing labor shortages
To help growers attract and retain farm workers, Monica Cooper, UC Cooperative Extension advisor for Napa County and her research assistant, Malcolm Hobbs, are conducting a survey of agricultural workers to determine the factors that affect job satisfaction. They found the number of female workers in Napa County has increased rapidly since 2013. “Women may be moving into the labor pool to fill vacancies caused by the decline in the number of male workers migrating to the U.S. for agricultural work,” Cooper said.
They plan to provide participating companies with custom recommendations for recruiting and retaining workers.
“We will also be generating a generic summary that will be widely shared with participants and non-participants at the close of the study. For now, we cannot make any general conclusions or recommendations because data collection is ongoing,” Cooper said. “We are aiming to distribute our final report this winter, so stay tuned.”
To help growers reduce their need for hand labor, UC Cooperative Extension viticulture specialist Kaan Kurtural designed a “touchless” demonstration vineyard that is mechanically managed. The mechanized vineyard is one of six trellis systems he is studying for water use, nitrogen use efficiency, yield and fruit quality of the wine grapes.
“We're always looking for ways to improve yield, quality and to reduce cost,” said Francisco Araujo, director of viticulture for Atlas Vineyard Management. “In light of the labor shortage we're facing right now, Kaan is exploring new production systems that include new trellises, mechanization, different types of mechanization from pruning to shoot thinning and trunk suckering. He's obtaining information about how these new trellis systems that he is investigating are going to play with yield and quality.”
The touchless vineyard experiment started out as a demonstration at first, but with grower interest, it turned into a full-blown research project.
“It started as way of saving labor costs, but when we started looking at the physiological aspects of how these plants grow, we saw the benefits from the quality point of view in addition to the labor savings,” said Kurtural, who is based in the Department of Viticulture and Enology at UC Davis.
A traditional vineyard in the Napa area is about a meter or 36 inches above the vineyard floor with vertical shoots held up with wires, which are moved by hand.
“We said, ‘Why don't we turn the system upside down?' Grow a tall trunk then put the bilateral cordon about 62 inches above the vineyard floor, that way we can push the rows a lot closer,” said Kurtural, who oversees the 40-acre Oakville experimental vineyard. The leaves grow down to generate the same leaf area as a traditional vineyard, but the leaves in the mechanized vineyard use water more efficiently so the no-touch vineyard requires less water compared to traditional vineyard systems.
“This is a dense system, this is 1.5 meters by 2 meters, roughly 1,340 plants per acre – we're getting by here on a third to quarter acre foot of water,” Kurtural said.
“It costs us roughly about a dollar in labor operation costs to manage each plant in a traditionally farmed vineyard of roughly about 1,300 plants per acre on the North Coast now,” Kurtural said. “The no-touch plants are costing us about 7 cents in labor operations costs.”
“The biggest expense is pruning, after that we go through what they call trunk suckering, which is also done mechanically here, and after that they will do shoot removal to open up the canopy. That's also done mechanically. After that, if there's need, they will do leaf removal, that's also done mechanically. And one last resort, if there's too much crop here, they will shake off excess berries with a harvester.”
The conventional system yields up to 5 to 6 tons per acre whereas the mechanized vineyard yields 7 to 8 tons per acre.
“These clusters set far fewer berries than a traditionally managed vineyard, but the berry size is also very small, which is what the winemakers like,” he said.
During harvest, grapes picked by machine are sorted on board the harvester so they go into the winery in uniform sizes, whereas hand-harvested grapes have to be sorted on a tray before they are put into the press tank.
“We made wines from these last year and compared to our traditionally farmed vineyards. Until we tell people what it is, they cannot distinguish the quality of the fruit or the wine.”
Weed and pest management
John Roncoroni, UCCE weed science farm advisor in Napa County, discussed options for weed control among young grape vines.
In the past, many vineyards were fumigated before planting for disease control, but it also provided weed control for young vines.
“With the loss of most fumigants for use in vineyards, hand-weeding was often used to accomplish this task,” Roncoroni said. “Increased costs and decreased labor force have made hand weeding impractical. Mechanical cultivation, at this point, is too imprecise – either leaving weeds close to young vines or causing damage by being too close.”
Covers on young vines allow the use of many post-emergence herbicides to control weeds, but Roncoroni cautioned that application of post-emergence herbicides on vines that aren't protected by mature bark may damage or even kill the vine.
“Herbicide use on vines less than 3 years old is a risky endeavor,” Roncoroni said. “Follow all label requirements, paying special attention to soil and irrigation recommendations.”
Lynn Wunderlich, UC Cooperative Extension advisor for the Central Sierra, and Franz Niederholzer, UC Cooperative Extension advisor for Colusa, Sutter and Yuba counties, demonstrated how to calibrate sprayers and to get uniform coverage when spraying fungicides.
In 2016, UC Davis researchers identified the three-cornered alfalfa hopper, Spissistilus festinus, as a vector of grapevine red blotch virus. Cindy Preto, a Ph.D candidate in the UC Davis Department of Entomology who is assisting UC scientists studying the three-cornered alfalfa hopper's biology and host plants, provided an update on their research.
Araujo, the viticulture consultant, said he and his colleagues value the university's research. “Napa Valley is a place where quality is paramount yet more and more we have labor shortage, we have inflation, production costs are going up,” he said. “Finding a way to get maximum quality along with yield levels that will pay for the increasing costs of production is the only way we'll be sustainable now and in the future.”