I needed to write this up for a class, so I figured I might as well post it. It’s lengthy & may
be best for wine geeks. I hope it does a decent job of discussing hand versus machine harvest & a few other options for vineyard managers & winemakers.
One of the most important steps in producing quality wine is the actual harvest. Picking the grapes at the right time for the wine desired and getting the grapes to the winery in a timely fashion, in the best shape for the wine desired, and at the optimal temperature is crucial. There are many options available to a vineyard owner and the options they choose will impact the finished wine. These options break down broadly into questions of timing and method of harvest.
The timing of the harvest depends on a number of factors including legal restrictions, type of wine being produced, winery capacity, and the local weather. Certain wine regions have specified start dates for harvest. In France the 17 wine regions each decide on a “day 1” of harvest for their region and this date is put out with the publication of the Banns of the grape harvest. This date generally corresponds to 100 days from the first flowering in the vineyards of the region. Wineries begin with the end in mind. That means the type of wine being produced is crucial to timing harvest. While there may be a theoretical optimal phenological ripeness for grapes, actual optimal ripeness depends on the winery’s planned finished wine. For a sparkling wine, acid may be favored over ripeness/sugar, so the wine may be picked earlier. For a full-bodied Zinfandel, the grapes will probably hang weeks longer than for a subtler wine made using the same grape. In Germany, the difference in wine category depends on sugar content and that may inform the timing of harvest. Weather also may impact the options available to the vineyard owner. If the weather turns unexpectedly hot, harvest may be advanced to preserve acid. If there is a brief rain, harvest may be delayed to allow the grapes to return to balance rather than picking water swollen grapes. If a huge amount of rain is forecast, harvest may be accelerated. Prior to harvest we always used to have a detailed calendar with dates for each grape from each vineyard that we would press for ourselves or for custom crush customers. When heavy rain or hail was coming our way, that calendar would go out the window as we rushed to save the harvest and pick what we could handle as quickly as we could handle it. This rush to harvest highlighted a final way in which timing can be influenced by something other than phenological ripeness. Even the largest wineries have limits to how many grapes they can process per hour and how much wine their fermentation vessels can hold. Lack of tank space in a smaller winery can lead to delays in harvest while waiting to move wine from a fermentation vessel into another type of storage vessel.
Before discussing the advantages and disadvantages of mechanical versus hand harvesting, it should be acknowledged that sometimes no option is available to the vineyard owner. If you have a monopole in Burgundy, you are required to hand harvest. For Bonnezeaux AOP, Quarts de Chaume AOP, and Coteaux du Layon Chaume Premier Cru, hand harvesting in successive tries in mandated. This is also the case in Banyuls. Cremant de Loire, St Chinian Roquebrun, St Chinian Berlou, Corbieres Boutenac, Blanquette de Limoux and many other areas/wines require hand harvesting to comply with the guidelines for the region.
After determining when to harvest, for those who have options, the question becomes how to harvest. Manual, or hand harvesting and mechanical harvesting are the two options. Of course, some vineyards will combine methods by hand harvesting the ends of rows, or difficult areas, and mechanically harvesting the rest. Here are the strengths and weaknesses of these two options.
Hand/Manual Harvesting Hand harvesting is the traditional method of picking grapes and was the only option for thousands of years. Grape bunches are cut by hand using only hand tools. These might be as basic as a sharp knife, or as advanced as electric secateurs.
Manual harvesting gives the vineyard manager and the winery greater control. It allows picking grapes in successive tries, whether this is for production of wines with noble rot, or whether it is just assuring that only ripe grapes are picked. Manual harvesting requires very little equipment. For a small vineyard, the investment in secateurs and baskets may be all that is required to bring in the harvest. Hand harvesting allows for whole cluster pressing, which creates a variety of opportunities. Hand harvesting is a gentler process than mechanical harvesting. It should result in fewer broken grapes arriving at the winery. This can increase the quality of the final wine because only the best grapes go into the wine. Fewer broken grapes also allows for a longer transport time to the winery without fermentation starting, or red grapes beginning to show color from skin contact. Manual harvesting also virtually eliminates the problem of matter other than grapes (MOG) entering into the production chain. Finally, manual harvesting works everywhere. It may be backbreaking work to hand harvest on the hills of Piemonte, the Mosel, or Oregon, but it can be done relatively safely by hand. Ancient bush vines in Greece or Lodi, or elsewhere can produce wonderful wine, but they must be picked by hand.
Manual harvesting takes more time than mechanical harvesting. This can negatively impact quality in two different ways. First, it is harder to pick a vineyard in one night without a large amount of people. The picking may start at night when the grapes are cool, but may have to continue into the heat of the day. It is generally preferable for grapes to arrive at the winery cool. Once grapes have been picked and start to warm, a number of chemical processes will begin. Not all of them will be good, and microbial growth at this stage may lead to off flavors in the final wine and may require the use of additional SO2 to combat that growth. The increased time to harvest also means that for some large vineyards, harvest may start when the grapes aren’t quite ripe and then continue until they are overly ripe with the idea that the overall profile will work itself out. This can lead to lower quality wine. Timing also becomes a huge issue when inclement weather threatens. If a storm is rolling in, there is only so much that can be picked by hand and the vineyard may lose enough grapes that they can’t make a profit. Manual harvesting is also expensive in large vineyards. It is estimated that, depending on the region, it may cost three times as much to hand harvest. Finally, on a social scale, grape pickers have historically been exploited. When small vineyards were harvested by family and friends, this was not a problem. By the time of Steinbeck’s Grapes of Wrath, poor working conditions and poor pay were endemic to the grape industry. While this is changing, it is still a consideration. Training is also a factor, since all of the advantages of picking for quality evaporate if the workers can’t tell the difference between good and bad grapes.
Whole clusters obtained through manual harvesting allow for a large range of production techniques. Carbonic maceration techniques require unbroken grapes. Champagne permits only hand harvesting for whole bunch processing. Hand harvesting also presents the opportunity of an initial selection in the vineyard. This is helpful in producing the best wine and is especially helpful in regions where there are limits on yield. Hand harvesting allows a winery to leave the vineyard at the proper yield limit rather than just picking everything & then having to discard bad grapes at the winery. This means that the winery can produce more & better wine under the same yield limits. Hand harvesting also makes it easier to produce quality rose’ wine & blanc du noir wines, including sparkling wine. Since the grapes should arrive as whole grapes and whole clusters, the winery has more control over the introduction of skin contact. That can lead to higher quality wine. Generally speaking, hand picking grapes allows the winemaker to have all possible options at the winery. If they want skin contact or no skin contact, they make the choice. If they want stem inclusion, they can choose at the winery. If they want to whole press all, or part, of a lot, they make the decision. Finally, wines made with hand picked grapes have a better perception in the marketplace. They are associated with higher quality and that means that they can sometimes command a higher price.
Labor for picking grapes is climbing in price and the labor pool is shrinking. Finding 120,000 people to pick grapes in Champagne for three weeks a year gets more difficult every year. In Portugal, there has been a population shift from the country to the city and this has decreased the available pool of people to work harvest. Immigrant work for harvest has become more and more important over the years. In Europe there are political issues related to refugees and that has impacted the attitude and opportunities for immigrant labor. In the United States, the government has traditionally turned a blind eye to illegal immigrants who have been migrant workers picking grapes and other crops. As the Mexican economy has improved, the pool of available workers has shrunk. To compound the problem, the U.S. government is stepping up raids of illegal immigrants. In some cases, this has led to crops rotting in the field. This hasn’t happened yet in the grape industry, but there is concern that it will. A new threat to the supply of workers has arisen in states like California where marijuana production has been legalized. Marijuana producers pay as much as three times the going rate for picking grapes. The work also is indoors, with portions of it air conditioned. There are more harvests per year, and some marijuana companies are offering medical benefits. The net impact is that it is harder to find people to pick grapes in areas like Mendocino and the people that you find must be paid more money, which increases the cost of the final wine.
Mechanical Harvesting This is mechanized picking of grapes. It generally involves over the row harvesters that drive through the vineyard using rubber or fiberglass rods to shake fruit off of the vines and deposit it into trailing bins. These bins can be very large or very small depending on the machine & the wishes of the vineyard/winery.
Since the 1960’s, mechanical harvesting, along with temperature-controlled tanks has been probably the greatest contributor to the advancement of the wine industry. It has allowed the industry to expand into areas where the labor pool did not allow manual grape harvesting (Paarl South Africa, major areas of Chile, Argentina, & Texas. It has allowed the industry to continue in regions like Portugal where the traditional labor pool has decreased. It has allowed mass production of wine in areas like the Central Valley in California. The lower price of production and the speed of harvest has contributed to there being more technically sound and affordable wine available now than at any time in history.
Mechanical harvesting can allow the grower to harvest at exactly the right moment of ripeness for their wine and to pick it and deliver it to the winery cool from the vineyard. Mechanical harvesting is at least five times faster than manual harvesting, generally harvesting an acre in slightly under an hour. While some manual harvest it done at night, it is difficult & takes even longer than usual. Mechanical harvesters are well lit, and since they just follow the rows, a well-trained operator can harvest just as quickly at night as during the day. Newer vineyards are often planted using GPS systems & the harvester can have the same GPS coordinates plugged in. That means that an actual operator is barely required for some of the newest generation of harvesters. Newer harvesters have optical sorting capability, they are gentler on the grapes, which means that rip grapes fall and green grapes stay attached to the vine. Mechanical harvesting is improving all of the time, while manual harvesting is probably at its peak efficiency.
There are some places where mechanical harvesting is not physically possible, or where it is dangerous. It isn’t impossible to work the slopes of the Mosel with a small mechanical harvester, but there is a real chance or rollover and death. Other areas are just too steep to use them at all. Mechanical harvesters can only make so tight of a turn. In areas where vines have been planted close to a house, winery, or physical barrier, the turn radius may be too tight to use a harvester. In those cases, a portion of the vineyard will still need to be hand-picked. Vine spacing and vine training also can make mechanized harvesting difficult or impossible. If vineyard rows are planted too closely together, the rows will have to be hand-picked. I was recently in a vineyard in Argentina where they are experimenting with tight spacing and close rows due to overly fertile soil. They may solve their vigor issue, but the vineyard must be worked completely by hand. Bush vines cannot currently be picked mechanically. While pergola training systems are rarer than they were, it should be noted that they are not conducive to mechanical harvesting.
Most mechanical harvesters shake the fruit until it drops off the vine. This means that stems are not included, which means that carbonic maceration is not a possibility, nor is whole cluster fermentation. This takes away options from the winemaker and can limit the quality of the wine that can be made.
Older mechanical harvesters are pretty brutal to the fruit. The aggressive shaking broke grapes. That meant that while the grapes waited for transport to the winery, they were exposed to oxygen and the fruit was getting skin contact. That lead to oxidation, browning of grapes, loss of aromatics, or oddly changed aromatics, and bacterial growth. It is also impossible to make a blanc du noir or a decent rose’ if the grapes have traveled a long distance floating in juice from the grapes that have broken open.
There has been a belief that mechanical harvesters allow for more MOG. Even with quality harvesters, there seems to be an increase in insects and worms that are harvested. This can lead to growth of harmful bacteria in the wine and off flavors.
Many mechanical harvesters just pick all of the fruit. That means that they get the good with the bad, the moldy, & the under ripe.
While mechanical harvesters cost less to pick an acre of grapes than manual harvest, that is only the operating cost. The upfront cost of a mechanical harvester is expensive, with the newest versions costing as much as $400,00 U.S. dollars. Of course, used harvesters are always for sale at lower prices, but older harvesters are more damaging to grapes and have other limitations. Renting harvesters or using a service are options, but then you are at the mercy of someone else’s timetable and are dependent on their skill and their maintenance capabilities.
Mechanical harvesting has huge opportunities on the horizon. Each generation of harvester seems to be better than the next. New systems like the New Holland Opti-grape harvester destem fruit, then use an optical sorter to send grapes to the proper bin based on programmed parameters. The Optimum from Pellenec supposedly brings in 99% clean fruit, which is probably better than what hand picking manages. As mechanical harvesters become more accepted, it is likely that vineyard managers will plant vineyards with them in mind. In Portugal the Socalcoes were designed with mechanization in mind. Row spacing for mechanical harvesting will be a consideration for large producers. As the labor pool shrinks, more regions will have to allow mechanical harvesting in order to bring in their harvest.
The largest threat to mechanical harvesting may be perception. No one like to admit they mechanically harvest. There is a perception that hand harvested fruit is better and that wines produced that way are worth more money. This perception probably limits the spread of mechanization more than some of the physical limitations. There may also be an outcry against mechanization because it cuts jobs. That doesn’t currently appear to be a problem, but it absolutely could become one in the future.
Vineyard management and wine making is not a one size fits all proposition. There are different options for grape picking depending on the type of wine you are making, the weather, the topography, the rules under which you produce wine, and other subtler reasons. Vineyard managers and wine makers will have to choose the best option for themselves and will need to consider all of the components above.