An Oregon State University horticulturist is developing improved cherry varieties on rootstock in combination with training systems that reduce the size of the trees and thus require less labor.
Lynn Long, based in Wasco County, said the research has its roots in a historical trajectory. In the 1970s, cherry orchards consisted of giant trees commonly harvested on 22-foot ladders. Fast forward to the 1990s, when growers began utilizing shorter, more densely growing trees. What is new is the ever-shrinking labor pool, which has driven growers to become more interested in dwarfing rootstocks and increasingly dense orchards.
“We wanted to try to reduce the amount of time it took to pick an acre of cherries,” Long said. “By doing this, we relieve some of the pressure on growers to find pickers who may not be there in the future.”
Part of why workers are so hard to come by has to do with the labor intensive nature of the harvest of this particular crop. To pluck a juicy, ripe cherry from a bushy branch, workers must typically climb a tall ladder to reach them.
“When you put pickers on ladders, it reduces their productivity by almost half,” Long said. “They have to set up the ladder, climb up the ladders, and reach for the fruit. Ladders increase the potential for accidents because pickers have to be higher off the ground. Pickers having both feet on the ground increases their productivity and reduces the risks for both the worker and the grower.”
Training the tree to a shorter height means growers use less labor. So Long and other researchers have investigated the performance of three main types of these training systems.
One of these training systems was developed by Washington State University and is called the Upright Fruiting Offshoots system, known more commonly by the slightly spacier term, the UFO training system. This system involves training the trees on a wide trellis.
“It’s a system where no branch hangs down, and it’s an upright system so that it has a free fall for the fruit,” Long said. “If a branch is shaken, fruit can come down into a catch basin without impacting the quality of the fruit. This is one of the systems developed to be able to automate the harvest. We looked at machines to help automation of the harvest and consumer acceptance of cherries picked with machines.”
The harvest can be automated to a great extent, but it depends on the training system, Long said. Fruit quality is imperative for cherry growers, so a cherry dropping from the tree cannot be bruised and battered.
A team at OSU, WSU and California State University studied automating the harvest using systems like UFO. The machine-picked cherries had one big difference from the hand-picked ones — no stems.
“Taking off the stem is a bit of a paradigm shift for consumers who may say, ‘I’m not sure I like this cherry without a stem on it,’” Long said.
So the team did side-by-side marketing consumer research and found that the stem-free cherries were still well-accepted. They are just not yet in commercial development, he said.
“In the interim, we have been looking at some systems that increase productivity of the plants so fewer pickers are needed. The advantage for pickers is that they are able to pick the fruit much faster with the trees that have these systems. Growers can make more money and save time,” Long said.
Ideally, orchards would be able to use what is known as a pedestrian system, a term that came out of France to refer to any system in which you can pick 70 percent of the fruit from the ground without the use of a ladder, he said.
Another one of these pedestrian systems that Long studied is called KGB, or Kym Green Bush from Australia. In this system, 100 percent of the fruit is picked from the ground without the use of a ladder. This system has multiple branches and involves a bush system with single upright branches, reaching a height of eight feet.
The third system Long studied is called the Super Slender Axe system. This system allows orchards to have high density and can be planted two feet apart in a row and 10 feet apart between rows. It’s also an extra-precocious and high-yielding system, he said.
“We’ve been looking at the advantages and disadvantages of these three systems for efficiency, quality and yields,” Long said. “The reason is to provide growers options with various systems that produce good quality fruit at high yields and help increase efficiency.”
Growers have seen some of the fruits of this research already. The KGB system, in particular, is being used by growers throughout the world, including several in The Dalles, where Long works.