Mechanical Harvesting of Grapes
Monday, 19 December 2011 14:50
Field trial reports covering machine harvesting can be found at different sources. This project records the observations made during the Kansas mechanical harvester feasibility study and addresses issues to be considered if contemplating a move toward mechanization. This report also reflects information from a harvester workshop in Nebraska.
To begin, consider the following comments from the American Fruit Grower trade magazine:
Perhaps only about 20% to 35% of winegrapes are still hand picked, though estimates vary. That is down from 40% to 65% just a decade ago and because of increasing costs the figure will likely drop all the way down to 15% a decade from now. “It’s really dwindling, but there’s always going to be someone who’s against (machine harvesting)”, says Robbie Roberts, the sales manager for American Grape Harvesters of Fresno, CA. “But it’s funny how some of them change their attitude when it hits their pocketbooks”. Mechanical Marvels, David Eddy, American Fruit Grower, June 2004.
Most local discussions about moving toward machine harvesting start with two perceived problems: fruit quality and potential damage to vines and/or trellising. We will discuss these issues as well as the economics of mechanical harvesting and other miscellaneous issues.
Fruit quality is of the upmost importance and is always a primary consideration in every vineyard operation. The goal of this project was to determine if there was an impact on fruit quality (positive or negative) when an operation uses machine harvesting instead of hand harvesting. In order to make this determination, rows within the same blocks at the Smoky Hill estate vineyard were harvested both by hand and by using a harvester. Enough fruit was harvested under each method to ascertain the quality of the must (post crusher juice/skins/seeds mixture). Following are the details and observations.
- Harvest Delay Effect – Harvest activities are scheduled when the fruit is analyzed as “ready for harvest”. Because hand harvesting often needs to be scheduled for Saturdays, there can be a significant change in the fruit parameters before Saturday. Scheduling harvests for Saturday, instead of when perfectly ripe, often results in harvested grapes that are either under- or over-ripe. Due to the extreme heat in 2010 harvest, this factor caused a large impact on the must quality. Separated by 4 days, the pH went through such a drastic increase that the musts started at a difficult level for the winery to manage into excellent wine. Probably the single most positive factor for machine harvesting is that the fruit can be picked when it is exactly ready.
- Heat Index Effect – Hand harvesting usually starts early morning when the sun first rises. Most vineyards try to have the fruit picked by noon. The grapes picked first will sometimes sit in a shaded enclosure, but mostly sits in the open air. As noted above the heat during harvest was extreme in 2010. The resulting effect on the hand-picked fruit was that it often reached the vineyard some 30 to 40 degrees hotter than the machined fruit. This had a very dramatic effect on the must quality -- impacting the aroma and flavors -- and made fermentation rates very fast, resulting in other wine quality issues. It is important to note that when the fruit is ready for harvest, the machine can be run during the darkness of early morning, yielding cooler fruit and having a very positive impact on the must quality.
- Fruit Damage – It is often argued that machines damage the fruit and hence degrade the must quality. Our trials showed the must quality was not impacted in either way due to the machine harvesting. The unit used for this study was a Braud self-propelled unit that was equipped with gentle rods. There is a number of existing research trials documenting the fact that older technology units without gentle picking rods did damage fruit.
- Matter other than Grapes (MOG) – Observations were made regarding the amount of MOG in the form of leaves, sticks, stems, etc… This is an area where the machine can have a negative impact. There are devices that can be adapted to the machine (MOG Wheel) that remove some of these items. The hand harvested fruit does have some stray leaves, but rarely any sticks or other things found within machined fruit. Though this was minimal and we could not ascertain the impact on the wine quality, this must be recommended as an item from the machine operation to monitor and reduce or eliminate.
- Transportation Time – The machine will harvest an acre in under an hour, whereas hand harvesting an acre will often take 4 to 5 hours or longer, depending on the number of pickers and their skill level. Transportation distances will remain the same, but because of the faster harvest, vineyards will be able to deliver to the winery much earlier in the day. Consequently, vineyards may be able to cultivate customers that otherwise would be out of their “heat-index delivery zone”.
Potential Damage to Assets (vines and trellising) and other trellis concerns:
In general, some vineyards may be established with a trellis system or layout that does not allow for machine harvesting. Metal t-posts can cause high wear on the machine rods, spacing can be too narrow or many other things can just make the vineyard unable to be harvested by machine. Each vineyard operator should request a tour of the vineyard by the harvester operator early in the season to be sure the vineyard will allow for machine harvesting.
Specifically, we observed damage to vines did not occur unless the vine trunks and cordons were way outside the vine row. Mechanization does require straight rows; if not, the vines will be damaged. Shoot damage was not an issue. Trellis damage was observed on pine posts that had dry rot at ground level. Trellis damage was also observed if the trellis did not follow a straight line. If mechanization potential has been considered when the vineyard was established, damage to the vines and trellising should be minimal or non-existent.
There are economic factors associated with either form of harvesting. Following are some observations and information learned locally and from other states that have machine harvesting services. Each grower needs to consider how these factors fit their individual operation.
- Harvester Costs – For a used self-propelled machine with gentle picking rods the unit costs are between $85,000 and $200,000. There is a transportation cost to deliver the unit; and a trailer to transport the harvester will need to be purchased. The height of the harvester requires a special drop trailer that can easily run $10,000. In addition to the purchase costs, there are also annual costs. It is assumed 300 acres would need to be harvested in order to reach a pay-back position on the unit.
- Annual operating costs – If purchased, there is an annual “sunk” cost related to the purchase price of the harvester. Above that, there would be annual operating costs: operator, maintenance, etc. The harvester co-op in Nebraska indicated direct costs associated with the harvester was $.06 per pound compared to $.10 -$.20 per pound for hand labor.
- Purchase considerations
• Vineyard: size, row spacing, training system, height of cordon.
• Machine reliability and user friendliness.
• New vs used.
• Self-propelled vs pull-type.
• Enclosed cab vs not.
• Fruit delivery system: bin or chute.
• Ability to accommodate different trellis styles (high wire, VSP, Geneva double curtain).
• Funding assistance programs.
- Hand Harvest Costs – Vineyards located by major metropolitan area often can find a volunteer base to allow for “free” labor. There are costs associated with this method as most vineyards will provide lunch, drinks, tee shirts or other items. For this study the Smoky Hill vineyard does not have such a volunteer pool and, therefore, pays a typical rate of $200 per ton. Research showed that vineyards pay between $100 and $200 per ton. There are also picking costs (picking totes, cutting tools, scales) in addition to the costs mentioned above (lunch, etc).
- Machine harvest rates are typically around $500 per acre and have a mobilization charge depending on the distance traveled (assume $500 on average). Note the suggested machine rates are per acre, not per ton. Also, custom harvesters may set minimum acreage requirements to even come to a vineyard. Hand harvesting versus machine harvesting costs are equal at approximately 2 acres. Above two acres the cost is lower for the machine harvest costs and below 2 acres it is higher.
- Co-op Considerations – Due to the high amount of acres required to bring the harvester costs to break-even and the small amount of acres within Kansas, having a harvest co-op or being able to hire a custom harvester is a necessity for most operations. A co-op would bring with it the structural and business issues of ownership, insurances, loss and/or profit sharing, etc… which when coupled with the long pay-back time, would steer many people away from harvester ownership and toward utilizing the services of the custom harvester. The custom harvester would be an entity that owns and operates the machine and trailer and charges vineyards for the harvesting services.
- Fruit Transportation Costs – Transportation distance is an economic issue that each grower needs to consider when selling to a winery on a “delivered” versus “FOB vineyard” basis. Discussions between the grower and the winery need to be on-going as the price of fuel increases and decreases. Long transport distances by either the harvester or the fruit can have a significant impact on overall costs.
- Management efficiency is increased while management overhead is significantly reduced when used a harvester. Example: a weather delay at the vineyard is just two phone calls: the harvester operator and the winery. Weather delays with hand harvesting can involve up to 75 calls, if that many pickers are used. Example: Vineyard labor requirements for a mechanical harvest would be the vineyard manager, a tractor driver, and a person to “clean up” the row ends. Vineyard labor requirements for a hand harvest requires all contracted pickers plus at least one more person to weigh the fruit and walk the picked areas to be sure there is no fruit left behind.
- Fruit loss can occur from hand pickers not getting all the fruit within the canopy. Assuming a chute fruit delivery system, losses can also occur during machine harvest if the tractor/trailer driver is not aware of the fruit stream coming from the harvester spout and does not have a bin in the proper position. Both of these are factors that can be observed and managed to avoid.
- (Assuming machine harvest) time is freed up for the vineyard manager by reducing both onsite time and picker coordination time. If the vineyard is also a winery they will have less overtime requirements for wine production employees. Machine harvest will also allow the winery to receive and process grapes during the week, leaving weekends open for events.
- Transportation requirements if choosing a cooperative form of ownership:
- Over-the-road truck and drop-trailer (unless the vineyards are close enough to move the harvester by driving it on public roads).
- CDL operator needed to transport harvester from vineyard to vineyard.
- Wash-out tank with pump.
This specialty crop grant to study the feasibility of machine harvesting grapes has been a very valuable grant and has yielded much information. Mechanical harvesting offers many advantages for Kansas vineyards and Kansas wineries. In short:
- Dependability - no worries about laborers not showing up, weather issues are minimized.
- Harvest time is shortened, increasing fruit quality delivered to wineries.
- Nighttime harvests are possible (and practicable), also increasing fruit quality.
- At and above 2 tons/acre yield, costs are less than for hand harvests.
Mechanical harvests would require closer coordination between the grower, harvester, and winery, but that is still less coordination than that required by hand harvests. Increased equipment would be needed including larger harvest containers (such as macro-bins), forked equipment to lift harvest bins, and equipment to transport harvested grapes from the field to the transportation trucks.
One of the most important outcomes of the grant is the observations that fruit quality was not negatively impacted by the machine (other than small amounts of MOG). It is safe to conclude that the machine harvested fruit is of greater quality. Machine harvesting also has a positive impact on fruit temperature, which can offer significant impacts on wine quality.
In general, the machine provides the best opportunity for efficient planning and management of the fruit harvest for all the reasons discussed above. Therefore, the only possible considerations for not using a machine to harvest fruit in a vineyard that has trellis allowing for machine harvesting would be vineyard operators desire to hand pick or the size of the vineyard not allowing for the economic feasibility.