by Enrico Villamaino
Cherry trees are large, with complicated architectures, but they bear small fruit. Proper cultivation and care of cherry trees results in a heavy dependence on labor.
Dr. Matthew Whiting, a horticulture professor specializing in environmental control of fruit quality at Washington State University, led the presentation “Opportunities for Mechanizing Sweet Cherry Production” during the recent virtual Great Lakes Expo.
“Mechanizing many of the tasks in a cherry orchard can greatly reduce this dependence on labor while improving both production efficiency and overall labor safety,” Whiting said.
Cherry trees can grow in unruly and unusual shapes. Over the last 30 years, researchers, nurserymen and growers have manipulated the large tree’s physiology into the smaller yet more productive tree seen in modern, high-density orchards today.
In 2010, Whiting developed his “UFO” system of orchard management. Short for “upright fruiting offshoots,” the UFO method utilizes simplified fruiting units for easier maintenance pruning, which can be mechanized, and good light interception. The UFO system employs permanent horizontal wood structural supports. An emphasis is placed on two-dimensional growth, with the aim of producing a “fruiting wall” as opposed to a less productive three-dimensional canopy. Harvesters working in a UFO-styled orchard pick 102% more pounds per minute of cherries than they do in a traditional open center orchard.
According to Whiting, the benefits of mechanical pruning in a UFO system are considerable. “It’s fast, and you’ll enjoy both uniformity and ease of operation. On average, mechanized pruning is 13 times faster than when it’s done by hand.” Potential drawbacks of the UFO system include non-selectivity and difficulty in reaching the leader.
Another method Whiting described is the “KGB” system. The KGB system is named for the shape of the tree it uses, the Kym Green Bush. Australian cherry farmer Kym Green started using this method in the 1990s. The KGB system is seen as very pedestrian and picker friendly, with 20 or 30 upright shoots short enough so that pickers can reach all the fruit on the tree by simply bending the canes without the need for ladders. Growers also favor KGB for its relative simplicity and lack of trellis or wires. Pickers in a KGB-styled orchard pick 54% more pounds per minute of cherries than are harvested in an open center orchard.
As with the UFO system, mechanized pruning of a KGB-styled orchard yields uniformity and shorter pruning times. Whiting pointed out its drawback as well. “As with UFO orchards, it’s non-selective. And there seems to be the belief that it might increase the chance of disease, but I haven’t seen any conclusive evidence of that.”
Even when mechanized pruning is brought in to supplement, rather than replace, hand pruning, the results are considerable. “Mechanical-assisted pruning is still seven times faster than hand pruning alone,” Whiting noted.
When it comes to harvesting, mechanization can be a considerable cost saver. “Harvesting is at least 50% of your overall costs. Whether you’re going to go in for a mechanical-assist approach, like shake-and-catch, or move to a fully mechanical harvest, you’ll be taking a lot of the labor costs out of your number one expense,” he said.
The “shake-and-catch” method of harvesting is seen as more of a short term solution. It utilizes a handheld limb-shaker, hook, fruit catcher and depositing tube. It works with many types of orchard architectures, can improve efficiency fourfold and yields stem-free cherries. A fully mechanized harvest is a longer term prospect. This method requires investing in heavy machinery. It also produces stem-free cherries and increases efficiency 50-fold, but it does require a Y-trellis structure.
Regardless of the method used, Whiting supported using machinery for postharvest hedging. He hailed it as a great time saver and an optimum way to improve light exposure to the orchard. “There does seem to be some debate about whether mechanized postharvest hedging results in decreased formaldehyde production,” he said.
Whiting concluded that there are a lot of reasons why cherry farmers should mechanize. “But if I had to give one answer… this is the direction that the industry is moving in. So if someone asked me why they should mechanize, I’d tell them it’s because they’ll have to.”