Growers develop custom over the row harvester for harvesting high density tart cherries
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EmailThe long-standing need for improvements to the traditional tree-shaking method of harvesting tart cherries has led one group of highly innovative growers to seek new strategies.
Michigan is a top producer of tart cherries in the United States, with 75% of the nation’s tart cherry acreage. Traditional tart cherry orchards are typically the Montmorency variety grown on Mahaleb rootstock, planted 19 feet by 21 feet. These traditional orchards result in very large trees that can remain productive up to 28 years, and they are harvested using a tree-shaking harvest method. Unfortunately, the traditional method of harvest using shakers requires that trees be 7 to 8 years old before they can be harvested, requiring significant financial investment prior to generating any revenue from new plantings. Mechanical shakers also have the potential to damage tree trunks and reduce orchard longevity. Damaged trunks can attract trunk-boring insects, such as the American plum borer, or peach tree borers, which can further contribute to tree decline or death.
The long-standing need for improvements to this traditional tart cherry system has led one group of highly innovative growers to seek new strategies. Oxley Farms, led by Ed, Chris and Rick Oxley, grows 250 acres of tart cherry in Lawton, Michigan. In 2010 when a hailstorm destroyed a 50-acre block of 1-year-old tart cherry trees, the Oxleys reached out to Michigan State University Extension for guidance since MSU horticulturists had been experimenting with alternative high-density plantings and over the row (OTR) harvesting techniques. With input from MSU horticulturist Ron Perry (now retired), the Oxleys decided to cut the damaged trees off just above the graft union to invigorate new growth. They also planted two new trees between each surviving tree to establish a high-density cherry planting. The idea was to see if the higher tree density would reduce tree size through competition among the root zones of each young tree.
The Oxleys first used a modified OTR blueberry harvester to harvest the experimental block. The method worked well as long as the trees stayed small, but the Montmorency on Mahaleb rootstock trees refused to remain small, even with tighter spacings. That meant they needed a larger machine than what was currently available on the market. After a deal with a manufacturer to build a specialized OTR harvester fell through, the Oxleys decided to build their own machine, borrowing ideas from grape, blueberry, cherry and coffee harvesters. The harvester they built uses rotary tines to shake fruit off individual limbs, rather than shaking the trunk of the tree.
The new machine has many advantages, such as being able to harvest trees that are only 3 to 4 years old rather than waiting until they are 7 to 8 years old as with a traditional shaker. This allows the farm to generate revenue from new plantings much faster. This OTR machine is also about three times faster than a trunk shaking harvester and is also gentler on the trees, which could have long-term benefits for maintaining orchard health and reducing pest pressure.
The Oxley’s newest plantings have trees spaced every 9 feet along the row while maintaining a standard row width, meaning there are twice as many trees per row, but the row width still allows for a trunk shaker to be used once the trees are too big for the OTR method. The high- density plantings are harvested for 3 to 4 years with the OTR machine and when the trees get too big for that machine, the Oxleys remove every other tree to make room to harvest the remainder with their standard trunk shaker. This is an inspiring example of how grower creativity and ingenuity can lead to ground-breaking innovations on the farm.
