Hi Fodder Followers!  About 40 foothill growers and wine industry folks turned out yesterday for my UCCE Sponsored "Transition to Mechanical Harvest Field Day" held at Dick Cooper's ranch in Plymouth, Amador County. With guest speaker Dr. Kaan Kurtural, UC Davis Viticulture and Enology Specialist and hosted by Dick with help from Kevin Steward of Trinchero, the morning held a good discussion of machine harvest, concerns of quality, and the lack of labor. Attendees gathered in Cooper's Charbono bilateral cordon trained block that had been grafted over and trained from head trained Zinfandel 4 years ago to listen to Kurtural field questions on vineyard requirements for mechanical harvest. Kurtural is a part of a national network of scientists and student researchers working on the "efficient vineyard" concept.   A large part of his research has been in mechanization. According to Kurtural, the critical thing is to get the stake at the head of the vine, and to use taut, 11 gauge wire to hold the fruit load.  The ends of the cordons need to be anchored to the wire as well, to prevent the machine from dragging the vines.  Many trellis systems can be harvested, depending on the machine, and the cross arm doesn't dictate success since there are trunk shaking machines that can harvest high quads with 48 inch cross arms.  Approximately 20-25 feet on the ends are needed to turn around with a machine like the Gregoire Pull Behind.  

The Charbono block that Dick had grafted over had a few shoots retained down on the trunk at the graft union which will need to come off for mech. harvest-these shoots were left to help devigorate the top so that the grafted bud wouldn't be shot out with spring flush.  Kurtural noted that when grafting over from established rootstocks (this block was on 110R), there can be alot of vigor transferred to the scion in spring.  Grafting over can also take place in fall, perhaps a safer time to make large cuts and avoid infection from canker disease.  Vines need at least 10 days to grow a graft union and you want 6 inches of lignified shoot growth before fall frost hits.  Of course, it isn't necessary to

graft over; if a grower wants to keep the variety, then head trained can be converted to cordon trained without losing a season of fruit.  In that case, at least 3/8 inch diameter canes are chosen in late spring and laid down on wire-the shoots should be tipped at the 5th position in order to promote terminal growth and not bush out at the bend.  The rest of the vine can remain as head trained until after harvest, when the lower arms can then be removed.  

The group then moved to take a look at the Gregoire pull behind machine Kevin Steward, vineyard manager with Trinchero Family Estates and Terre D'Oro Winery (located right across the street) generously brought over for the group to take a look at.  The Gregoire had a "bow rod" head type of picking system, which means the fruit is shaken off of the vines using adjustable nylon rods.  The berries fall down  (without the rachis) onto Lexan or Nylon overlapping catcher plates that open and close as needed to work around vine trunks and trellis posts.  The berries are then moved to the top with either a bucket or belt system.  Trinchero has been using their machines for several years and is happy with

the quality of the fruit.  Quality is a concern for some; although, it was estimated in 2013 that 80% of California's winegrapes are machine harvested.  Machines are equipped with multiple suction cleaning fans to blow out leaves and other "MOG" (Material Other than Grapes) as well as magnets to remove nails and spikes, etc.  Research comparing machine and hand-picked grapes for quality was mostly done in the 1990's or earlier.   Clary et. al. (AJEV, Vol 41, No. 2, 1990) did work comparing hand harvested grape quality to trunk shakers and cane strikers.  They found no difference in MOG between the 3 methods, and no difference in yield; although the

Kevin Steward and Trinchero's Gregoire Bow Rod Machine

machines harvested second crop while the hand labor left it, the machines do not harvest the rachis (stem).  For quality, a very large consideration is fruit temperature. Harvesting at night may be done more easily with machine, and larger bins (gondolas) means fruit stays cooler longer, preventing fruit oxidation, browning and the production of off-flavors.

Lastly, we took a look at Dick's leaf remover-an Italian machine that sucks in the leaves and shreds them and spits them out the back. Dick loves this machine and uses it the day of harvest to cut "windows" into the thick canopies of his famously popular Barbera vines-making it easier for the pickers to find the fruit.  

Is mechanization the answer for the labor issues facing the foothills? Looking at the numbers, it appears to pencil out, but some blocks are still too small, and too steep, and some winemakers and growers still prefer hand harvested fruit.  As long as their are hands to do the harvesting.

For those interested, the handout from the mechanical harvest field day is available here.