Growing & Winemaking


To Blow Up or Down?

December 2009
by Paul Franson
Rather than pulling warm air down to the vineyard floor, the Selective Inverted Sink whisks cold air away from susceptible vines.

Until global climate change warms things up a lot more, grapegrowers will still have to deal with frost. Certain techniques that growers once used are becoming difficult to implement, but alternative approaches are proving useful for many others. For example, some growers are enthusiastic about surface-mounted fans that blow cold air up and out of vineyards.

The oldest approach is to set fires in the vineyards, burning diesel fuel, old tires or wood to raise the temperature a few degrees before the heat escapes into the atmosphere. That technique is no longer allowed in some North American grapegrowing regions due to environmental worries, but it is still practiced in some areas. “A layer of smoke hangs over the valley when we get untimely frost,” says Bret Neal of Stoney Mesa Winery in Cedaredge, 50 miles south of Grand Junction in Western Colorado.

A second method, from the mid-20th century, uses wind machines on towers to blow warmer upper air down into the vines, but these devices are running into increasing resistance in some places, too, because of their noise—up to 97 decibels in some old equipment.

Modern wind machines are much quieter. Doug Riddle of manufacturer Orchard-Rite Ltd. Inc., says, “The wind machines vary in noise depending upon model. We have models that will range from approximately 55 to 70 dB measured at 300 meters. These are approximate numbers and they may change with the atmospheric conditions.”

The prices also depend on the model, engine type and location. They range from approximately $25,000 to $30,000.

Some vineyard owners are looking at alternative methods of frost protection, such as spraying copper sulfate, bacteria or lamp black, and laying down solar quilts that lie between vine rows, absorb solar radiation and reflect it back to the vines. While these have been tried with some success, ground-mounted fans may be most promising.

Neighbors vs. wind machine

In Napa Valley, where home buyers in rural areas have to sign “right to farm” papers acknowledging nearby farming activities, at least some neighbors are protesting an unusually loud wind machine on a 4-acre vineyard owned by John Bierylo near Silverado Resort.

neighbor fan
According to a county report, the 50-year-old machine hits 97 decibels from across the street. The average frost fan is 70 to 80 decibels; because this is a logarithmic measure, 97 dB is far louder—comparable to an aircraft landing a mile away—four times as loud as 70 dB.

Neighbors have begged Bierylo to replace his fan with something quieter, but he has refused, citing the widely accepted tenet that property owners in Napa County have the right to farm their land.

County agencies and local vintner organizations tried to broker a deal, but they reached no solution. Bierylo reportedly has even been offered a quieter fan for free if he’d pay to install it.

Now, after a two-year stalemate, the Napa County Board of Supervisors is considering a county ordinance aimed at quieting Bierylo’s fan. The catch: It will also affect 39 other properties, though only eight of them have wind machines. The ordinance would limit fans on small parcels in non-agriculturally zoned areas of the unincorporated county to 85 decibels.

Grower groups including the Farm Bureau are fighting the ordinance while they try to persuade Bierylo to replace the fan.

Surface fans
The fans, dubbed Selective Inverted Sink (SIS), were developed by Uruguayan hydro-mechanical engineer Rafael Guarga and are sold here as the Shur Farms Cold Air Drain. One unit will protect up to 10 acres, depending on the terrain and conditions.

Anthony Aellen of Linganore Wine Cellars in Mt. Airy, Md., uses a Shur fan, which blows cold air from ground level up to 300 feet into the air to protect his 60 acres of French hybrid grapes. His vineyard is a test site for Cornell University.

He’s had the fans for about a decade, and is enthusiastic about their protection. “Think of it as a reverse drain,” he says. “On a cold night, cold air flows down. We can’t open a hole in the ground, but the fan blows it up and out.”

He uses two of the machines in frost pockets, which he bought after hiring helicopters to try to protect his vineyard. “They flew from midnight to 7 a.m. at a cost of $850 per hour, but we still lost 80% of our buds.”

He looked at wind machines, but was discouraged by the loud noise, cost and the need for an 8 x 8 x 8-foot cube of concrete required for anchoring them.

He estimates the wind machines at $30,000 to $40,000, and they use much more fuel. His cold air drains cost $5,000 and get by with 5 gallons of gas for a whole night. “You can hardly hear them,” he claims. They’re movable with a forklift.

At the vineyard, 30 miles west of Baltimore, fans protect half of the 60 acres. They protect vineyards that slope down to a hill, but his other acreage is flatter, so he would have to build drapes or barriers to keep from trying to suck all the cold air in the area out.

Aellen is adding another 55 acres of grapes, and he plans to add Shur fans to protect them, too.

Bret Neal at Stoney Mesa Winery in Colorado has both a wind machine and a Shur fan—or SIS, as he calls it. Neal says, “If you grow grapes in Colorado, you have to have frost protection.” He&rsq uo;s had the SIS for six years and the wind machine for eight. Neal says they work together to protect his 8 acres. “We run the SIS first,” he says, “and if the temperature continues to drop, we use the wind machine.”

Neal operates the SIS from a tractor PTO, though many are supplied with self-contained gas, diesel or electric engines. He says the fans have proven that they work, but he feels he needs more protection and is looking at adding heat.

Nick Ferrante of Ferrante winery near Cleveland, Ohio, uses four conventional wind machines from Orchard-Rite, powered by propane. He first installed two wind machines—one for each of his 15-acre vineyards—in 2004, after the devastating winter of 2003. He then realized that he needed more coverage and installed two more. He has since repositioned the wind machines.

He finds they’re useful, but do have significant limitations. For one thing, they can’t be used when the wind is blowing more than 5 mph.

Ferrante says he finds them effective in fighting winter bud kill if it isn’t too cold, and in spring, down to about 28°F. Unfortunately, they’re somewhat dependent on the state of the inversion layer. “They’re limited for preventing killer frosts,” Ferrante says.

Limitations on sprinklers
The other popular method of frost protection—sprinkling vines with water—is under pressure in California.

According to Nick Frey, president of the Sonoma County Winegrape Commission, the National Marine Fisheries Services sent a letter to the California Water Resources Control Board asking for an emergency ruling to ban the use of water from the Russian River for frost protection in the Russian River Valley basin. This request was made because of fish kills in the Russian River in 2008.

The Water Board denied the request for enforcement this year, and gave the industry one year to develop a plan for frost protection.

Penalties are severe and may include criminal or civil charges. Criminal charges are $50,000 per incident and/or up to a year in jail. Civil charges are $25,000 per incident.

Many growers will continue to have adequate water from ponds or other sources, but droughts and continuing pressure on water will surely impact growers in water-short areas such as most of California and Washington.

Another method, using microsprayers that create a mist, was examined and endorsed in “Microsprayer Frost Protection in Vineyards” by G. Jorgensen, B.M. Escalera, D.R. Wineman,?R.K. Striegler, D. Zoldoske and C. Krauter of the Center for Irrigation Technology at California State University, Fresno, in 1996.

Brent Edwards, an expert in water uses in the vineyard, says that these sprinklers’ main benefit is restricting water to the vine rows rather than covering the whole vineyard. He says they can operate with 15 to 16 gallons per minute per acre, rather than 60.

He warns, however, that they must be turned on a little sooner and run longer. And they tend to freeze up due to the lower flow. In addition, they require a lot of labor to maintain the typically 350 to 400 sprayers per acre instead of 25. A commercial product called the Pulseator was developed for this purpose, but it doesn’t seem to be on the market at present, due to a dispute between the patent holder and former manufacturer. The patent holder is apparently trying to arrange manufacturing for the unit.

None of the growers who spoke to Wines & Vines believed their frost protection equipment to be foolproof. Weather events like the Easter massacre freeze of 2007 in the central and eastern states can be so severe that nothing truly protects a vine’s new growth. For those many other occasions, however, when a couple of degrees Fahrenheit determine the difference between a good harvest and a marginal one, many growers believe that frost protection is a good investment.


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