MSU Extension Cherries

Michigan is the top producer of tart cherries in the US, with 75% of the nation’s tart cherry acreage. Michigan State University has a long legacy of conducting research to improve the tart cherry industry in the state, through breeding programs, horticulture and physiology research, and improved pest management. MSU researchers often work with commercial growers to explore ideas and study new growing strategies.

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 7-8 years old before they can be harvested, requiring significant financial investment prior to generating any revenue from new plantings.

Seen here, is a traditional tree shaker. The trunk is shaken causing fruit to fall onto a conveyor which then carries fruit to collection bins.

Mechanical shakers also have the potential to damage tree trunks and reduce orchard longevity as seen here. 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, MI.

In 2010 when a hailstorm destroyed a 50-acre block of 1-year old tart cherry trees, the Oxleys reached out to MSU for guidance since MSU horticulturists had been experimenting with alternative “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, borrowing ideas from grape, blueberry, cherry and coffee harvesters. The harvester they built is pulled by a tractor and powered by its power take-off. When the machine encompasses a cherry tree, its rotary tines shake fruit off individual limbs, much like a blueberry harvester. The cherries drop onto conveyors that carry them rearward to water-filled bins that keep them cool. When a bin is full of fruit, the harvester automatically drops it on the ground. A forklift following behind places another bin on the harvester in continuous motion.

This machine is able to harvest trees that are only 3-4 years old, rather than waiting until they are 7-8 years old as with a traditional shaker. This allows the farm to generate revenue from new plantings much faster. This OTR machine is also and about three times faster than a trunk shaking harvester. The OTR system is also gentler on the trees than a standard trunk shaker, which could have long-term benefits for maintaining orchard health and reducing pest pressure.

Now able to harvest smaller trees, the Oxleys have continued to experiment with different high-density planting strategies and some dwarfing rootstocks.

Their 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.

This planting is harvested for 3-4 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. There are many remaining research questions to fully understand the potential of this planting and harvest strategy, and MSU will keep working with the growers in Michigan to explore new strategies and continue to move toward a competitive and profitable agricultural future.

Acknowledgements:

• Oxley Farms
• MSU Project GREEEN
• Michigan Cherry Committee
• MSU Horticulture
  • Jim Flore (retired)
  • Ron Perry (retired)
  • Amy Iezzoni (retired)
  • Greg Lang
  • Todd Einhorn
• MSU Northwest Michigan Horticultural Research Center
  • Nikki Rothwell
• MSU Entomology
  • Heather Leach
  • Julianna Wilson