Good Fruit Grower

September 2013

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Page 13 of 47

Over-the-row HARVESTING T he first commercial harvest of Montmorency tart cherries planted in a hedgerow-like structure and picked using an over-the-row blueberry harvester took place in Michigan this summer. For the record—since this could be an event of historic significance—the harvest took place about two o'clock on the afternoon of July 11 in the orchard of Ed and Phyllis Oxley and their son, Chris, near Marcellus, Michigan. In 12 minutes, the Korvan 9000 Vertirotor, with Chris at the helm, gathered two-thirds of a tank of cherries, clean and undamaged, from two rows with 180 trees. The trees were small, the crop was light, and hail damage made the fruit unsuitable for normal pitting and processing, Oxley said. Instead, the cherries went to a winery that makes cherry wine. The machine traveled at 1.3 miles per hour, the shaker frequency was set at 850 vibrations per minute, and the ethephon-treated cherries were removed with a pull force of 180 grams. The significance of all this becomes clear when one realizes how far from "normal" this process was. Michigan State University horticulturist Dr. Ron Perry was there to explain it to the 20 or so people who came to watch the harvest. ABOVE: Ed Oxley talked to son Chris, the driver, as Ron Perry prepared to observe the harvest. BELOW: Ed Oxley was convinced the harvester would work—convinced enough to grow 20 acres in a new orchard design. Good Fruit Grower witnessed the first harvest of tart cherries with an over-the-row machine. Mechanical harvest photos by by richard lehnert Tart cherry harvest was mechanized more than 50 years ago, first with limb shakers, later with trunk shakers. Since then, tart cherry trees have typically been grown on a spacing of about 19 feet square. They are harvested with trunk shakers and inclined-plane catching frames. To get a by Richard Lehnert trunk robust enough to be shaken takes six years, during which time no fruit is harvested. The trees grow tall, sitting atop four-foot-high trunks, and it takes a lot of alley space to move the shakers, catching frames, conveyors, and water-filled receiving tanks. Waiting six years for first fruit doesn't make economic sense, Perry said, especially since trunk shaking damages trees and shortens the life of orchards. The productive life of tart cherry orchards is clipped at both ends. Supported by Michigan's cherry producers and Michigan State University's Project GREEEN, Perry began looking at alternatives in 2008 with initial trials conducted on tart cherry seedlings in Dr. Amy Iezzoni's tart cherry breeding program. He had also been following work in Poland on that country's smaller Schattenmorelle tart cherry trees, on which researchers had been trying over-the-row harvesters since 1994. Then, in 2011, Perry and a team of MSU researchers established a trial for over-the-row harvesting at the Northwest Michigan Horticultural Research Center in Traverse City, using trees that included naturally compact varieties as well as Montmorency, and also pruning and training treatments. The trial included varieties from the breeding programs of Iezzoni and Dr. Bob Bors at the University of Saskatchewan, Canada, who had already been doing work with dwarf tart cherries and machine harvest. In the cold environment of Saskatchewan, Bors found that bush-like cherries survived the hard winters better and could be harvested with equipment already in use to harvest haskaps (honeyberries) and saskastoons. Adding cherries would expand the use of the machine into a new season. In 2008, Perry set up a machine harvesting demonstration using a blueberry harvester on an experimental orchard that Iezzoni developed. The orchard contained trees of all sizes and varying genetics, so it was a good way to test a new concept and see how the trees responded to it. "Lucky" hailstorm In April of 2010, a severe hailstorm devastated 50 acres of young tart cherries that grower Ed Oxley had planted. He sought advice from local extension educator Mark Longstroth, who contacted Perry. Oxley, who was very familiar with over-the-row harvesting because he used it for his juice grapes, was interested in trying a grand experiment. He had been following the MSU research team and observing their preliminary trials conducted in 2009 and 2010. He decided to restart 20 acres of those three-yearold hail-damaged trees by heading the trunks back to 18 inches high and letting new limbs develop. Some trees developed multiple trunks and are bush-like; others have single leaders, but all are bushy looking, with branches originated at 12 to 18 inches. The next spring, in 2011, Oxley interplanted two new trees between each of the old ones, converting the orchard to a 6- by 19-foot planting. "The goal was to develop bush-form trees in a hedge pattern," 14 SEPTEMBER 2013 Good Fruit Grower As a tree enters the throat of the Korvan, two passively rotating spindles each containing 760 vibrating fiberglass tines penetrate the canopy. Cherries are shaken off and fall onto the folding fish-scale bottom pan and then roll into conveyors on each side.

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