Growers learn about the UFO system in a cherry trial planted this spring at the orchard of Tim Dahle in The Dalles, Oregon.
Cherry production is going through a revolution, just as the apple industry did 30 years ago with new varieties, rootstocks, and training systems. But the revolution in cherries is happening much faster than in apples, observes Mark Hanrahan, a grower in Buena, Washington.
Hanrahan was one of the first growers to plant the Upright Fruiting Offshoots system for cherries, which Washington State University horticulturist Dr. Matt Whiting developed about three years ago. Already, the system has gone through an evolution as it’s moved from theory to reality, and Hanrahan says it will to continue to evolve so that it is adapted to mechanical harvesting.
Hanrahan, 40, began working on the family orchard at Buena when he was a child. He left to find another job in 1992 when his father wouldn’t let him plant cherries on the new Gisela rootstocks. He worked for a couple of years as farm equipment operator for WSU at Prosser, and then worked for Valley Fruit at Wapato, Washington. He took over the family orchard in 1998 when his father retired and has been planting trees on Gisela rootstocks ever since. He is now in partnership with Greg Gibbons.
When he heard about the new UFO system, he didn’t hesitate to plant it. “I needed a system,” he said. “The thing I noticed about a lot of the successful growers in our industry is they pick a system and then go with it.”
He knew the precocity of the Gisela rootstocks and how to grow them. He wanted a high-density system on a wire. And he recognized the need to rejuvenate wood to get the best fruit, and the difficulty of doing that on the old-fashioned open vase or central leader system with its horizontal wood. He figured that on a system with vertical shoot placement, similar to grapes, it would be easy to rejuvenate wood.
Labor shortage
During a grower tour to Hanrahan’s orchard this summer, Whiting explained that an impetus for developing the UFO system was a potential shortage of labor as cherry production increases. The two-dimensional system could accommodate mechanization and automation, including robotics and visioning systems. Besides improving labor efficiency, it would optimize light interception in order to produce high yields of top quality fruit.
Originally, Whiting recommended planting unheaded whips, which would be trained horizontally along a low wire that would become the bottom wire of the trellis and would almost fill the space in the first year. Buds on the top side of the leader were to be removed, leaving buds spaced 8 to 10 inches apart, which would grow up into vertical fruiting shoots. All the buds on the bottom of the leader were to be removed.
However, experience has shown that it’s difficult to obtain whips from nurseries because standard practice is to head them.
Whiting said leaving the whip unheaded was key to the concept of filling the space horizontally between the trees in the first leaf. If trees are headed, a top shoot must be trained along the wire instead.
Another lesson learned is that it’s not advisable to remove buds on the top side of the leader because if the buds don’t break, there will be a gap that will never be filled. That’s what happened in a block of Santina cherries at Hanrahan’s orchard. “I took the buds off and didn’t get the uprights,” he said. “I’ll never do that again.”
Now, Whiting recommends scoring the leader every 6 to 10 inches just above well-positioned buds and painting them with Promalin (benzyladenine and gibberellic acid) to encourage bud break. As the upright shoots grow, they should be thinned out to the right density. The precocity of the system in the third leaf is completely related to the breaks in the first year, Whiting stressed. He believes UFO plantings have the potential to yield three to four tons per acre in the third leaf and double that in the fourth and fifth leaf.
Whiting said the UFO system was designed to simplify pruning and training of cherry trees and has two basic rules. One is that the upright shoots must not be allowed to branch, and side shoots that grow on them should be ripped out to reduce shading. The second rule is that the most vigorous upright shoots should be removed on a rotation basis in order to renew the wood. The only permanent part of the tree is the horizontal leader.
“You get a natural hierarchy of uprights,” he said. “It becomes obvious which has to come out first. Take out the two or three largest.”
Hanrahan now has 20 acres of UFO plantings and has learned the importance of maintaining the apical dominance of the horizontal end shoot or main scaffold branch. In some of his third-leaf blocks, where he received feathered nursery trees, he planted the trees vertically, took out the central leader, and pulled over two feathers to either side along the wire, forming a two-leader version of the UFO. That enabled him to fill the space more quickly and generated higher second-leaf production, but it lacks the simplicity of the one-leader version, he said.
There also is a tendency for a leader to lose its dominance and for a strong upright shoot to take over. “If you’re going to grow the double-leader system, it’s important to grow your leaders first, and get them to their length, and then tie them down,” he said.
Rules are made to be broken, he said. “You cannot allow yourself to get into a box. You want to listen to everybody, but you have to take what they say with a grain of salt because they’re not in your shoes and they may not know.”
Mechanical harvesting
Despite the challenges, Hanrahan is committed to the UFO and now has 20 acres in that system. It has the potential to pay for itself by the fourth leaf, because of the early yields, and he hopes to use platforms to eliminate a lot of the ladder work. Researchers have tested the Darwin mechanical bloom thinner in his orchard.
The next step will be to develop the UFO into an angled canopy system that can be harvested mechanically. On an upright tree, the fruit would drop through the canopy instead of onto the catching surface of the harvester. He’s planning to plant Chelan on Gisela 12 rootstocks in 2011 on a Y trellis, training the upright shoots alternatively to wires on either side. The other essential ingredient for mechanization is a good quality cherry variety that detaches easily from its stem, and WSU is addressing that through its soft fruit breeding program, he noted.
“In this industry, we will transfer to mechanized harvesting,” Hanrahan said with conviction. “I don’t know how many years it’s going to take. It’s like Grady Auvil saying ‘Red is dead.’ It’s only a matter of time now.”
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