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[caption id="attachment_42277" align="alignright" width="350" caption="The best among the 15 tractor drivers Constellation Wines U.S. has in its North Coast vineyards operate mechanical harvesters."][/caption]

Constellation Wines U.S., the world's largest wine producer, is making a big move forward this year with machine harvesting for higher-end wines.

After a few years of experimentation in the vineyard and the cellar, the world's largest wine producer now is using harvesters for a little more than half the grapes bound for the company's higher-end wines from California and the Pacific Northwest.

Mechanized harvesting of winegrapes has been growing in use in California since the 1970s. But it's only been in the past few years that the machines have gained greater acceptance in the North Coast because of growing pressure to lower farming and production costs while maintaining or improving wine quality.

Mechanization has been rolling into North Coast vineyards for tasks such as pre-pruning and leaf removal, but it has been viewed skeptically for picking and sorting. Erik Olsen, Constellation Wine's chief winemaker, likened the perception to that of natural cork vs. aluminum screw caps, in which technology has progressed to the point that it can be a viable, economical alternative, under the right conditions.

"There are certain varieties and blocks where hand-harvesting will always be desirable when considering the terrain, the trellis system or the delicate nature of the fruit," Mr. Olsen said.

Potential problems for mechanical harvesting include lyre-style and other wide trellising, steep slopes and delicate-skinned grape varieties.

 Yet Steve Reeder, general manager and winemaker at Simi Winery in Healdsburg, said new harvesters with on-board vineyard-quality information systems and attachments for sorting and selecting fruit from material other than grapes (commonly called MOG) -- cluster stems, stem jacks, leaves, etc. -- have made mechanized picking feasible for luxury-tier wines.

A number of luxury-tier wineries have added hand sorting at the winery to avoid roughing up the grapes in destemmers or pumps. With minimal MOG in grapes arriving at the winery, Simi's team can dump the almost whole-berry pinot noir directly into fermentation tanks, and cabernet sauvignon and other red varieties need only a slight crush. Chardonnay and sauvignon blanc can be moved directly to the presses via a large screw conveyor rather than pumping from a destemmer, effectively doubling press capacity.

"With a shortage of harvest workers, machines are now poised to pick off a huge portion of what was being done by hand just a few years ago and deliver it to the winery with comparable, if not better, quality," Mr. Reeder said.

A harvest crew of three or four with a modern harvester can pick up to one and a quarter acres an hour at night, depending on row size and trellis system, comparable to the work of five hand-harvest crews totaling 25 to 30, he said. And moving harvesters from one vineyard to the next is faster than five crews and their tractors.

Constellation has found that hand-harvesting takes 23 labor hours per acre for 4.5 tons of grapes, and mechanized crews require two hours per acre to pick the equivalent amount, according to Keith Horn, Constellation Wines U.S. director of vineyards. That adds up over the thousands of acres the company farms.

Picking at night is becoming more commonplace both to prevent heat changes in fruit before it arrives at the winery and for protecting workers, and mechanized harvesting increases how much can be brought in by morning. That increased productivity is important in seasons such as this one, in which two major rain events have come in the middle of the harvest.

"Logistics can be easier than hand-harvesting when peak demand for picking is in play -- as you are not dependent on a crew to arrive, and thus have more control over the picking date, allowing you to harvest at short notice," said Janet Myers, general manager and winemaker at Franciscan in Napa Valley. "This can be especially helpful when inclement weather is on the horizon."

With up to three inches of rain in some North Coast areas in early October and an unexpected shower last week, wineries are triaging which grapes can be picked when most all the early-ripening varieties need to be picked, according to Glenn Proctor, partner as well as wine and grape broker for Ciatti Co. of San Rafael.

"You're either picking, waiting or praying," Mr. Proctor said. "There are a lot doing all three at one time."

The 2010 North Coast harvest was ugly, with a spike of 100-degree days coming just before harvest and then a soaker of up to five inches of rain falling just as growers were finishing with cabernet sauvignon. After another relatively cool season this year delayed grape development, 2011 turned ugly. The first rain came in the midst of the harvest of chardonnay, Sonoma County's top crop, and other early varieties such as pinot noir, petite sirah, sauvnignon blanc and zinfandel.

Constellation has less than half-done with its North Coast picking last week and expects to be totally finished by the first week of November. The company planned to be done with chardonnay in cooler Russian River and Potter valleys last week and is making it a priority to bring in merlot and malbec because of the risk of bunch rot. North Coast cab clusters have more air around the berries this year, lessening the rot risk, according to Mr. Horn. 

With the right configuration of vineyard rows and trellises,  machine design and configuration, and operator training and experience, quality of mechanically picked fruit can be better quality than that of hand-harvested grapes, according to Mr. Reeder. The operator has to continually watch the fruit going into the gondola for MOG and accordingly adjust the energy and movement of the picking head uses to remove grapes from the vine,  the speed of the harvester along the vine row and the speed of the fan to blow away MOG, according to Mr. Horn.

"A good driver will leave a few berries on every vine," said Mr. Horn. "This means they are using the minimum amount of energy to remove the fruit from the vine, and it is hard to tell whether or not a vine has been harvested [by machine]."