The way Mark Hanrahan envisions his new cherry block, there’ll be no ladders or even platforms around during harvest.
For his second-leaf Santina planting on Gisela 5 rootstocks, he’s using the Upright Fruiting Offshoots (UFO) system developed by Dr. Matt Whiting, horticulturist with Washington State University in Prosser.
Whiting’s goal was to devise a cherry training system that could accommodate new technologies, such as mechanical aids, and be more efficient in terms of light interception. The crop develops on upright shoots fastened to a trellis.
Though Hanrahan might use platforms for some types of work in the block, he expects the crop will be harvested from the ground.
“All we’ll need to do is unhook the branch from the top, bring it down, and play it like a violin into our buckets,” he told growers who visited his orchard at Buena, Washington, this summer.
Whiting said the UFO concept is in its second or third iteration and still evolving. Trees are planted at about a 45-degree angle with the trunk laid horizontal along the lower trellis wire. Buds on the underside of the trunk are rubbed off, and some are removed on the upper side of the trunk, leaving six to eight well-spaced buds about 8 to 12 inches apart that will form the upright shoots. When developed, the canopy should form an upright fruiting wall. The upright shoots will be renewed periodically, so that the only permanent part of the tree is the trunk.
Whiting said that with most cherry training systems, growers battle the upright growth habit of the cherry tree, which is apically dominant. The idea behind the UFO was to benefit from that upright growth.
“We’re focusing growth into well-spaced upright wood. That’s the way cherries want to grow,” Whiting said.
During a field tour this summer, growers visited the Benton City, Washington, orchard of Jeff Lunden, who has a first-leaf UFO planting. Lunden stressed the importance of communicating with the nursery supplying the trees to be sure they deliver unheaded whips. The Benton trees on Maxima 14 rootstocks that he received had been headed, which will make it more challenging to get the trees to fill their allotted space, he explained.
The ground was previously planted to Pluots but had been idle for a year. Lunden began by installing the trellis, then planted the trees eight feet apart and laid the trunks down along the wire, securing them with electrical tape. Because they were headed, the top branch will need to be laid down as an extension of the trunk to fill the space between the trees.
Growers discussed whether it would be advisable to tip the lower branches to allow the uppermost branch to become more dominant and fill the space. Whiting recommends no heading, to avoid stimulating lateral growth on the uprights, and said he would rather see vigor maintained by adequate irrigation and nutrition in the first year. “The goal is a precision canopy management approach, rather than tipping everything,” he said.
As the uprights grow, more trellis wires need to be added to secure them. With a between-row spacing of ten feet, the height of the trees should be no more than nine feet, Whiting said. A precocious rootstock is a critical part of the UFO system, because growth needs to be slowed down by early cropping, he added.
The group then visited an experimental second-leaf UFO planting of Selah on Gisela 6 rootstocks at the Irrigated Agriculture Research and Extension Center in Prosser. Trees are six feet apart, with ten feet between rows. Again, the nursery stock had been headed. Ideally, the trees should be connected along the lower trellis wire in the first year, Whiting said, but that’s challenging with headed trees.
Whiting expects UFO plantings to produce three to four tons of cherries per acre in the third leaf and more than double that in the fourth leaf, then reaching full production in the fifth leaf.
Growers have wondered if the system has enough bearing surface to hang a good crop on, Whiting said, but he does not think lack of yield will be an issue. “Yield potential is as high as you want it to be. It comes down to getting the right planting stock. The third-year yield is related to how much wood you can get in year one. All the first-year wood is fruiting wood in the third year.”
Mel Omeg, a grower in The Dalles, Oregon, asked if there would be a high enough leaf-to-fruit ratio to produce the nine-row cherries that bring the best returns.
Whiting responded that the system would require different crop management strategies, because thinning won’t be done with loppers. It may require blossom thinning, postbloom thinning, or even hand thinningperhaps from a platform. “I think it becomes reasonable when you have a structure like this,” he said.
Oregon State University Extension educator Lynn Long said he thought making dormant-season heading cuts and taking laterals off the uprights if necessary would be a quicker and more economical way to reduce the crop load than hand thinning.
Whiting acknowledged that vigor and crop load management are two aspects that need to be figured out as the system develops, but he’d prefer to be in a situation where the trees overset rather than underset, so the crop can be manipulated to achieve the right balance.
“Ultimately, we want more predictability,” he said. “If you’re going to err on one side, we want more fruit rather than less fruit. We’re learning as we go here. A year ago when I was presenting the conceptual diagrams, there was absolutely no heading. I have backed off. I think there’s a place for heading, but we want to avoid strong lateral growth. We want single fruiting uprights.”
Hanrahan, who has strong upright growth on his second-leaf planting, has been removing uprights (or pipes, as he calls them) that are more than half the diameter of the main trunk. Uprights that are between a third and half the diameter of the trunk were bent over and fastened to the wire after the first growing season, to slow down the growth without losing fruiting branches. They were tied back up in June. “We want to make sure the smaller branches have a chance to grow,” he explained.
When he planted the system, he removed buds on the lower side of the trunk but did not remove buds on the upper side because he wanted to let them grow and then be able to choose which upright shoots to keep. “You want as many pipes as possible so you can make choices later,” he explained.