Good for fruit quality and workers, but for the budget?

By Jane Firstenfeld
From March 2007 Issue of Wines & Vines

Whatever trellis system you decide on, using high-quality materials is vital. It will save maintenance costs down the road.

"Quite a bit of work was done in the '80s and '90s on the potential physiological effects of different trellises and exposures, looking into the basic concept of what trellising should and could do for you," according to Dr. Robert Wample, chair and director of the department of viticulture and enology at California State University, Fresno. Since then, however, new developments have been scarce, as research funds have been directed toward studies deemed more glamorous or urgent.

"There may be little new to offer," Wample suggested. "Over the past 20-30 years, there has been a lot learned about the basic physiological effects of trellis systems on vine productivity and potential fruit quality effects, assuming that the trellis system is managed in the manner for which it was designed. However," he said, "Some of the systems have been shown to have high management costs, and therefore they may not be achieving their potential in our current economic environment."

Issues to Consider

Choosing a trellis system for a new vineyard, or deciding to change an existing system, involves more than just economic considerations. It's a complex equation that varies for each vineyard, depending upon terrain, climate, preferred vine spacing, pruning and harvesting techniques, grape variety and irrigation requirements. The list doesn't end there, either. Some systems may be less cost-effective to maintain, and some, studies have shown, can lead to demonstrated increases in muscular/skeletal disorders (MSD)--repetitive stress injuries in vineyard workers, including carpal tunnel syndrome and spinal problems.

"Initial trellis costs are important, but more important is constructing a trellis system that will hold up for the life of your vineyard," according to Mitchell Klug, managing director of vineyard operations for Napa-based Premier Pacific Vineyards, which develops and manages premium vineyard estates in California and Oregon. "Our trellis costs range from $5,500 to $7,500 per acre. The higher costs are due to higher labor costs to install trellis systems in vineyards with rock soils, steep terrain or irregularly shaped blocks."

Klug said that, while it's possible to spend less for a new trellis system, "You can spend less money upfront for inferior materials, but will end up paying more in the future for maintenance costs. It's important to purchase your materials from a reputable source. When comparing costs, make sure you are comparing apples to apples," he emphasized.

"People are struggling today: How do we make any one of these systems economically viable?" Wample said, noting that the price of steel, grape yield and quality goals all make the trellising decision an important aspect of a company's ultimate economic payout. Of course, "Some boutiques are prepared to invest in more expensive systems, with a slower rate of return," he added. "The general trend in the industry right now is to keep the trellis system as economical as possible from the point of view of long-term care," including such elements as potential workers' compensation for injuries in the field.

Dr. James Wolpert, at the UC Davis department of viticulture and enology, said, "Since the industry settled on VSP as a standard," research activity has waned, concentrating in areas the industry sees as its problems and "investment priorities."

Premier Pacific, for one, considers VSP "the best and most practical trellis system to use" in its high-density vineyards. It can work quite well in windy exposures, Klug said, but where high vigor is desired, "A trellis system that could accommodate a larger vine and more nodes would be better suited to the potential for vigor expression. If the terrain favors a more east-west row orientation, then we would open up the canopy, or divide it with a cross-arm to be able to angle the shoots to protect the fruit from the hot afternoon sun.

Be Kind to Your Labor

Not only has VSP become accepted as the industry standard, at least in California, but 2006 research published by the American Society of Agricultural and Biological Engineers reveals that, of five commonly used winegrape trellis systems, "VSP was determined to be the optimal system in terms of decreasing relative MSD risk." Authors A.E. Kato, F.A. Fathallah, J.A. Miles, J.M. Meyers, J. Faucett, I. Janowitz and E.G. Garcia observed 11 experienced subjects, who performed simulated pruning and harvest operations on Lyre, Scott Henry, Smart Dyson, VSP 4x4 and VSP model trellises. Electrogoniometers gathered information on their postures during the processes.

According to the study, in the winegrape industry alone, work-related MSD incidences number 80 per 1,000 workers; the most commonly recorded injuries were attributed to MSDs of the lower back and the upper extremities. The VSP 4x4 system was judged "the least desirable from an MSD risk standpoint. The Lyre system would also be undesirable, due to the combination of increased trunk extension, increased wrist flexion and should er increased abduction angles" observed during the experiment.

"On the average," the study concluded, "The VSP system showed the lowest levels of risk to the wrist and the back during both pruning and harvesting. Hence, the use of this system should be advocated, especially if there are no substantial differences with respect to grape quality or vine productivity among the variety of trellis systems."

The Ways of Washington

VSP may be ideal for dense plantings in California's North and Central coasts, but conditions in the more extreme climate of Eastern Washington call for different approaches to many aspects of viticulture, including trellising.

Dr. Mercy Olmstead, extension viticulture specialist in Prosser, Wash., (and author of the cover crop feature in our February issue), reported, "The major trellis system being installed is a cordon-trained, spur-pruned bilateral cordon, with the cordon height at about 36 inches. We usually have at least one catch wire, and in some locations, two catch wires to train the canopy up on the east side of the vine for sun exposure. The west side of the vine has shoots that are allowed to hang over, creating some protection from possible sunburn."

According to Olmstead, this type of trellising is popular because of the prevalence of mechanical harvesting. Washington's grape harvest normally coincides with the annual apple harvest: the state's biggest fruit crop. So, although a few high-end vineyards do hand harvest, "Almost every grower has to have arrangements for hand harvesting, or a loyal crew year after year," Olmstead explained.

Olmstead considers pruning and harvesting techniques the most important considerations when choosing a trellis system, followed by climate. "You can make adjustments for most other considerations, but it's difficult to take a mechanically managed vineyard and go to head training and hand harvesting, because of the labor constriction--which will continue to worsen--and vice versa, because you may not have the trellis system set up the correct way," Olmstead said.

And, she noted, "Canopy management intensity (and costs) will also increase with increasing complexity of the trellis system, e.g., Scott-Henry vs. bilateral cordon."

How much money do you have to put in a trellis system? "With the price of steel increasing in the past five years, it is expensive just to put in one more catch wire, depending on your acreage," Olmstead cautioned, adding "With most trellis systems, a wire also needs to be placed below the vine for the drip irrigation tubing."

The overall initial cost of any system is a very important consideration, she said. "I think the difference in the price comes from how complicated your trellis system is. The more wire that you have, the more expensive it is, until steel prices come down."

Olmstead reported that the Washington Wine Industry Foundation (washingtonwinefoundation.org) is putting together a cost-of-production calculator to allow growers to input costs and determine establishment costs per acre, including different trellis systems. "A general rule of thumb that I tell growers is that it costs about $9,000 to $10,000 per acre to put in a vineyard, for trellis, irrigation system and plants," she said.

Friendly and Professional Advice

Although advances in trellising have been few in the most recent years, trellises have certainly become more complex since the ancient Egyptians incorporated them in the hieroglyph representing the grapevine. And once you've staked out your vineyard, you'll want to ponder long and hard before you change your system: Ideally, your trellis will endure and support your vines for their entire productive existence.

Our professionals stressed the need for careful planning before choosing and installing any system. "First, think about how you are going to manage the pruning and harvesting of the vineyard," Olmstead said. "Second, make sure your site and variety selection match, so that the fruiting wire and training system will be appropriate for the climate and variety choice. Finally, consider the economic input of certain trellis systems, and the price paid per ton or acre, to ensure that the bottom line will pencil out. Otherwise, a complicated trellis system may not be the best investment in the long run."

Mitchell Klug and his colleagues at Premier Pacific also advised asking your neighbors. "We suggest, if possible, that you visit vineyards in your area that are doing a good job producing high quality fruit. Discuss with them their system, and how it is working for them. What would they change if they could?

"It is also worth considering the expectations of your customers. They are an important part of the equation, and may have experience to lend to your very critical decision on choice of trellis."

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