Some cherry varieties, such as Skeena, naturally loosen as they reach maturity, while for others, including Bing, ethephon sprays can induce abscission. But not even abscission sprays will make some varieties, notably Chelan or Rainier, machine-harvestable, says Amit Dhingra, assistant professor of genomics and biotechnology at WSU in Pullman.
Dhingra is identifying which genes produce Skeena’s natural loosening and Bing’s positive response to abscission materials.
He’s narrowed the hunt by comparing cherry genes to known abscission-related genes in apples and other fruit.
His results should speed up breeding of high-quality varieties for machine harvesting, Whiting says. “Our ultimate goal is a full-season roster of varieties.”
Growers hope the breeding program reduces reliance on ethephon.
“It’s not a sustainable practice,” Hanrahan says. “It’s too weather-dependent.”
Market development also plays a part in the project.
“Clearly we need to develop markets if any of our technologies rely on [stem-free cherries],” Whiting says.
Packaging showcases stemless fruit Michigan State University researchers are working on new packaging to highlight the fruit’s different look.
Meanwhile, 60 percent of consumers in marketing panels preferred stem-free cherries when price and quality were equal, Whiting says.
Leaving stems on the tree should improve cherries’ post-harvest quality. “Stems cause a lot of damage to fruit through harvest and packing,” he says.
Hayden says he’s looking forward to building an orchard system—rootstocks, varieties, architecture and technology— that produces even better cherries more efficiently “without having to go in with [ethephon] or mangling the tree.”