CSUF Grape Day focuses on solutions to water, labor shortages

California State University, Fresno, showcased its grape growing and winemaking research, projects, and facilities to more than 75 growers, winemakers, and others at the university's annual Grape Day.

Growers heard research updates related to vineyard mechanization, pest control, irrigation management and other areas. The updates focused on helping growers cope with tightening water and labor supplies. Guests toured the Viticulture and Enology Department's vineyards, winery and sensory lab while gaining insights into what the department is doing to advance world class viticulture and wine-making in the San Joaquin Valley.

In a vineyard of Cabernet Sauvignon winegrapes, Robert Wample, department chair and director of the Viticulture and Enology Research Center (VERC), updated growers on the latest research on vineyard mechanization. In light of uncertain labor supplies, Wample said growers will need to continue incorporating mechanization throughout all facets of the operation to reduce the grower's reliance on hand labor.

“Growers are feeling the pressure to find ways to cut costs and improve the bottom line,” Wample said. “Mechanization in the vineyard is certainly not new, but we are constantly trying to do a better job.”

Mechanized harvest has become much more common in the wine grape industry, and VERC is working with equipment manufacturer Oxbo/Korvan Industries to develop machines that can mechanize pruning and crop adjustment practices in the vineyard as well.

Wample said recent wage figures and cost studies on mechanization reveal that mechanizing pruning and shoot thinning can save growers perhaps 20 cents per vine, or as much as 58 percent compared to hand work.

Greg Berg with Oxbo said the company is making significant strides in developing thinning and pruning heads that can be incorporated into vineyard mechanization equipment. The company is working with CSUF on ways to make the process better, more efficient and therefore more cost-effective. Berg is experimenting with different prototypes of pruning, de-leafing and shoot thinning heads that will work on the standard Korvan tool carrier.

The challenge, Berg said, is to mechanize the various labor-intensive vineyard processes without sacrificing yield or quality.

“We are trying to simulate hand farming with machines in both cost and fruit quality and then take that equipment to the winery level,” he said.

The trial at the university's vineyard in North Fresno is comparing mechanized pruning and shoot thinning to hand labor on a California sprawl Cabernet vineyard with 24-inch cross arms. Berg said that further work should help streamline the mechanization process.

“If we can travel faster your costs go down and that's our challenge right now,” Berg said.

The trial is also using GPS technology to do differential harvesting, allowing Fresno State researchers to identify higher quality areas in the vineyard and harvest those areas differentially in a single pass. Yield monitors developed by Korvan can help determine stronger spots in the vineyard and develop yield-to-quality ratio maps so that researchers can establish relationships between yield and quality in the vineyard.

High-tech irrigation practices were also showcased at the Grape Day as growers in the San Joaquin Valley grapple with water shortages. The manufacturer PureSense shared its system for real-time automated irrigation management that matches crop variables, environmental conditions and moisture status to fine-tune irrigation scheduling.

Ed Norum, an irrigation engineer at Fresno State, also shared his work on smart pivots that take advantage of automated controllers and advanced irrigation system technology to automate center pivot irrigations. Using instruments to measure environmental and crop conditions, as well as automated controllers, Norum hopes to develop smart pivots that can calculate irrigation sets based on crop need, harvest date and moisture status, and control overhead sprinkler applications using “smart” technology.

New pest control methods were also highlighted. Jim Farrar and Andrew Lawson in the plant science department at Fresno State demonstrated the use of thermal pest control for diseases and insects on table grapes.

The TPC concept, developed in Chile in 1999 and now available commercially worldwide, is still under review at the university farm. It uses forced hot air from propane burners attached to a PTO implement driven through the vineyard. Lawson and Farrar are in their first year of replicated study in Ruby Seedless table grapes at the university to test claims by the manufacturer that TPC can reduce pest and disease pressures while improving yield and quality.

Entomologist Andrew Lawson said the trial compares conventional pest and disease management and untreated controls to thermal pest control applications every two weeks from flowering to veraison, and weekly from veraison to harvest.

“We're in the vineyard a lot, blowing hot air,” Lawson said.

Plant Pathologist James Farrar said that TPC treatments don't make sense from a biological basis, because the 100 degrees C is not in itself enough to kill insects and pathogens. But there may be physiological responses in the plant that the team will continue to explore.

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