Stemless cherry research shows progress

Dan Wheat/Capital Press Jose Medina, 29, picks Rainier cherries at Skeat Orchards near Orondo, Wash., last July. Fruiting walls will replace trees and mechanical pickers for stemless cherries will replace human pickers in systems being researched in four-cherry producing states.

New orchards designed to rely on automation

By DAN WHEAT

Capital Press

PROSSER, Wash. -- Researchers are pushing ahead in the third year of a USDA Specialty Crop Research Initiative project that aims to improve production and marketing of sweet cherries.

Orchard trials in the $3.9 million, four-year project are showing great potential to improve precocity and yield in some varieties in Washington when using new rootstock and planar training systems, said Matthew Whiting, project lead and stone fruit physiologist at the Washington State University Irrigated Agriculture Research and Extension Center in Prosser.

These new orchards are well-suited to utilize automation and mechanical technologies for thinning and pruning, and ultimately, harvest.

Oregon State University, Michigan State University, the University of California and Picker Technologies of Bellevue, Wash., are involved in the project.

Genetic studies will reveal cultivars with clean release of the cherry from the stem and high fruit quality.

Researchers are making systems to grow cherries on fruiting walls where they can be mechanically harvested, reducing the need for pickers and improving safety. The team envisions adding field packing and the use of biodegradable packaging to extend shelf life.

A key part of the process is raising trees to the upright fruiting offshoots system -- called UFOs -- to create fruiting walls. The oldest UFO trial blocks in commercial orchards are in their fifth year. Trees are planted at a 45-degree angle to the ground and branches are trained to grow up trellises, which can be vertical or angled.

Tying the offshoots to the lowest trellis wire at the time of planting caused vigorous shoot development at the bend and unbalanced growth among upright shoots, Whiting said.

That was rectified last summer by tying the trees horizontal later in the season, after new shoots developed at the terminal end, and testing Apogee, a growth retardant, on individual shoots, he said.

"It's important to have balanced vigor in the first two years," Whiting said. "The biggest challenge in our five-year-olds now is not having the upright shoots positioned well and having unbalanced vigor."

Establishing a good structure early in orchard development is fundamental to achieving the goal of 10-foot-tall fruiting walls that can be harvested mechanically, he said.

Testing of mechanical harvest has evolved from impacting the tree to vibrating one branch at a time to minimize damage, Whiting said.

"Preliminary data from the shake and catch shows it would be more than twice as fast as picking by hand," he said.

Cherries need to be stemless for mechanical harvest and breeding for good release from the stem will take 10 to 15 years, Whiting said. Meanwhile, Selah and Skeena cherries appear to have fairly good stem release and Bing can if treated with a growth regulator, he said.

Whiting said he's pleased with the project's progress and that the biggest challenge is keeping all the elements coordinated.

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