As the prospect of an automatic apple harvester draws nearer, growers are increasingly seeking answers about which canopies align best with machine work and how to prune those canopies to meet the robots’ demands.
Robots won’t be able to reach around into tight spots in a canopy and can’t come close to the capabilities of a human hand. So the critical question for an automatic harvester is this: Can it go into the row and have clean access to a piece of fruit?
“Basically, if I can reach an apple with my hand, without having to go through or around a piece of wood, a post or a wire, then that’s accessible,” said Dan Steere, CEO of Abundant Robotics, a spinoff of SRI International that aims to have a machine harvester commercially available later this year. Last year, Abundant announced $10 million in venture capital funding to further development.
The company has been working in roughly a dozen Washington orchards, as well as in Australia and New Zealand, for several years as it develops the machine. Last fall, the company tracked accessibility of fruit in specific orchards; one orchard had a high of 86 percent accessible fruit, and the numbers fell from there.
So far, Steere said, what they’ve found is that fruit needs to be 24 inches off the ground, with the robot picking the entire height of the trellis up to 12 feet. Specs they’re aiming for: a 10-foot vertical row and a V with 12-foot row spacing and no more than 15-degree angle on the canopy.
He noted the biggest hindrances to an apple being “seen” by the harvester are if the fruit is clustered or if there is wood or a wire blocking it.
That poses some challenges in a V-trellis, said Dave Allan of Allan Bros. He was one of four representatives of companies working with Abundant who shared their experiences from harvest last year during the Washington State Tree Fruit Association annual meeting in December.
At Allan’s orchards, a vertically trellised orchard (11-foot spacing and 13 feet high) had 71 percent of its fruit accessible, but an angled V-trellis (12-foot spacing and 12 feet high) orchard had only 68 percent of its fruit accessible.
On the vertical trellis, Allan cut any big limbs growing out into the row, which did not decrease yield and improved quality with better light distribution. One mistake: leaving doubles too close. On an angled canopy, with more fruit occluded, he said, “we’re going to have to have darts downward and outward into the row.”
Allan said the industry should be able to set a goal of at least 85 percent of the fruit being accessible, which he called “doable.”
Jeff Cleveringa, head of research and development for Oneonta Starr Ranch Growers in Wenatchee, Washington, agreed that 85 percent is pretty achievable. “Beyond that, then it becomes a productivity loss and ease of picking,” he said.
Cleveringa had his crews make initial pruning cuts, then when fruit was golf-ball size on the tree, he went back through again to eliminate any down-hanging limbs. The work was performed in a third-leaf, 10-foot by 2-foot planting of Juicy, a club variety that is a cross between Braeburn and Honeycrisp. Production yield for the block was right at about 60 bins an acre, he said; making the additional cuts reduced overall yield by about 2 bins.
“In our vertical system, 80 bins is what we’re shooting for, and I think it’s attainable,” he said, adding that he thinks he can get to 85 percent of the fruit being accessible without too much additional work other than eliminating a few more down-hanging limbs that he missed. “I like my vertical wall, I can go from both sides.”
Valley Fruit Orchards doesn’t have any vertical trellis orchards, and it’s probably a good time to start looking at them, said Scott Jacky.
“I’m the guy who says, ‘We’ve got something that’s pretty close to working now, we’ll go from there,’” he said. “I want to try both.”
In the company’s V-trellis block of Pacific Gala on 13-by-2 spacing, with everything formally trained to a seven-wire system, 67 percent of fruit was accessible.
“Basically in the test area, we picked 82 bins to the acre; the rest of the block picked 105,” he said. “We got a little overzealous on the thinning, especially this year since thinning didn’t do anything for size. Other than that, we will cut more shoots back to keep that machine from sucking them up and damaging the apple.”
Jacky also said he’s relying on there being a reasonable amount of time for growers to transition from hand labor to robotics.
Ramon Cuevas of Washington Fruit and Produce said his goal is to pick 100 percent of the fruit and keep yields high. So far, he acknowledged, they have far to go, sitting at 63 percent of the fruit accessible in a 10-by-4 planting, 12 feet high, of Cripps Pink.
Crews pruned and removed a lot of wood but left some doubles, he said. Yields were probably 15 to 20 percent off from the rest of the block, though the fruit had better size and color. The block picked 90 bins to the acre overall and 73 bins in the test area.
“For me, I would love to start a little earlier in the pruning process. Going through it the first time around, I think we’ve learned a lot,” he said. “We need to reposition some branching. But it’s going to take some time.”
Steere closed the talk by noting that the top two-thirds of the orchards participating would be economically viable at the current levels of accessibility of fruit. “Once you go through it two or three times, the ability to bump up those numbers while still maintaining attractive yields, that capability is there,” he said. “That’s very encouraging to me.” •
—by Shannon Dininny