Bull suckers are already becoming obvious in this block of cherries on the Upright Fruiting Offshoots system that was planted a year ago at Orchard View Farms.
As researchers and growers learn more about the new Upright Fruiting Offshoots training system for sweet cherries, some issues are already cropping up.
A panel of growers—Mark Hanrahan from Zillah, Washington; Tom Thornton of Everson, Washington; and Eric Shrum, The Dalles, Oregon—shared their experiences with the UFO during recent cherry industry talks. The following are highlights of what they’ve learned thus far.
Bull suckers: Decisive action is required as soon as suckers are identified. Pruning them out may be the best option, but prune early. If you wait until the fourth leaf, you’ll be reluctant to prune because there is good fruit on the sucker, said Hanrahan. In hindsight, he said, he probably should have cut them out as soon as they were obvious. The three growers have not been successful in slowing down bull shoot growth by pinching buds or girdling the bull shoot. Hanrahan is going to try using nylon zip ties this year to girdle the bull in hopes of developing a smaller replacement shoot.
When starting the tree off, all new shoot growth should be removed until the tree bends to become horizontal. That includes rubbing off basal nodes, which typically are the ones that develop into bull shoots.
Steep angles: Trees should be planted on an angle at least 50 degrees from horizontal—the steeper the better. Hanrahan and Shrum have angled the trees 50 degrees from horizontal; Thornton has his at 70 degrees. With flatter angles, be prepared for more sucker growth in the center of the trellis.
Varieties: Most varieties can be adapted to the UFO, though some may require scoring of limbs and application of Promalin (gibberellic acid and benzyl-adenine) to encourage lateral branching. But precocity is a must. Dwarfing and semidwarfing rootstocks are recommended. Less positive responses will occur with rootstocks like Mazzard or Maxima 14.
Cost: Planting and establishment costs are higher than for conventional cherry training systems because of the higher density of trees and trellis structure. Hanrahan estimated that his establishment costs were around $11,500 to $12,000 per acre for a 9 x 10 foot spacing. Tree training costs have been about $1.50 per tree. However, money is returned earlier to the grower, starting in the third leaf, with a good crop in the fifth.
Longevity: All three growers are interested in finding out if the UFO has legs for the long term. Will UFO trees, when they are 20 years old, still be able to produce good crops?
“We need to be able to keep growing fruit on young wood, year after year, to have high quality,” Shrum said. “The apple industry has changed a lot in the last few decades by going to trellis systems. Is that where cherries are going?”