Aug 16, 2020

Cherry field day takes virtual look at techniques

When you can’t take the grower to the orchard, why not bring the orchard to the grower?

That is what representatives of Washington State University (WSU) and Oregon State Extension Service did in early July when they hosted the first-ever Virtual Cherry Field Day in a sweet cherry orchard at Allan Bros. Inc.’s Zilch Ranch near Zillah, Washington.

The live online video presentation was conducted with an in-orchard broadband connection by WSU tree fruit Extension specialists Bernadito Sallato and Matthew Whiting. They were joined by Allan Bros.’ Suzanne Bishop, research and development director; and Luke Anderson, Yakima Valley area manager.

The orchard visit was preceded by presentations on Little Cherry Disease, WSU robotic pruning research and cherry harvest studies.

“This next portion as a live broadcast has never been tried before, and we will be conducting it while staying six feet apart, per the regulations,” Whiting said in introducing the next element of the field day held in two different areas of the orchard block. The session appeared to come off without a significant hitch, and attracted a host of virtual attendee questions for the experts.

Bishop, who has been with Allan Bros. for five years, is now part of a three-person research and development unit. She said the company is aggressive in trying new horticultural strategies.

“I’m happy to see Suzanne in this role,” Whiting said. “In the Northwest, in particular, we’ve seen a lot of these vertically-integrated companies beginning and supporting their own internal research and development. To be able as a university researcher to connect with those people and partner with them, you can really expand on the key issues that produce top-quality fruit.”

Bishop shared strategies for a Sweetheart on Mazzard rootstock block that’s trained to a Y-trellis system.

“For us at Allan Bros., there is a difference between V-trellis and Y-trellis,” Bishop said. “With a Y-trellis, we have the main trunk and two vertical leaders going up, and then more growing horizontally, extending from each of those two vertical pieces. On a V-trellis, it’s alternating trees, going back and forth along the V. Those are usually closer-density trees, as well.”

Adapting to conditions

Allan Bros. took over management of the orchard in 2010, after it was planted by another operator in 2006.

“It was already mature when we started managing this block,” Bishop said. “It has been trained somewhat to the wire, but there were a lot of sparse branches coming out of the tree. We had trouble getting yield. We were strategically putting branches in between the wires. There are four wires. It wasn’t trained just to get extra branches within those windows between the wires, but also branches coming out is where we’ve seen benefits in yield and been able to get better production out of this.

The previous ranch manager said the most difficult task in managing the block was the excess vigor.

“We’ve had to spend a lot of time managing the tops,” Bishop said. “Besides that, for this site, (Sweetheart on Mazzard rootstock) seemed to be a really good combination. The good thing is we already have that Y-trellis, so you’re already dividing the vigor into two different branches, so it does help.”

Anderson said even though Allan Bros. didn’t plant the block, “we have similar structures (in other locations) to what we have here.”

“We buy a full-size tree, we’ll plant it and then we’ll figure out where we are in relation to having the two leaders come up,” Anderson said. “We’ll head the tree immediately after planting. As it grows, we will get our twine on the trellis, and start trimming it to the structure. As soon as any limb grows, it comes out. We’ll train it down to the wire. That doesn’t happen until year two. Before then, we usually get the tree to a height of about six or seven feet in the first year on each side.

“The second year, we’ll do the scoring, which we do around stage two, according to the WSU cherry bud chart,” Anderson said. “We’ll score anywhere we want the limb to break, with about four or five scores above and below the wire. As any branch comes out, ideally we want to tie it down to the wire or tie it down into the row.

“We have planted structures like this the past few years, but it’s our condensed version at this point,” he said. “This orchard is 10 by 20; we’re going 5 by 13, and we’ll see how that goes.”

Anderson said that “some of these branches really start to peter out, even at 5 feet, and the vigor goes down tremendously. When you’re in close, you get those nice shoots, which is what we want. What we tell our guys in terms of detailed pruning is (cut) a foot and a half off of the branch. We’ve noticed if you just maintain that foot and a half, you really space out your structures six to eight inches along the wire and we get that wood that we want.”

After taking over management, “we started bringing the limbs out into the row,” he said. “We have about six to eight limbs that we bring out. This has really increased our yields. We’ve doubled our yields the last couple of years. We have started to notice some rot issues at the bottom. As you go up, the branches get larger. We want to switch that.”

This past winter, Anderson said, trimmers “were really aggressive on the tops. We have no mercy on the tops. If it’s 50% of the leader, it is a candidate to be cut out, no matter where it is on the tree. That has helped maintain good fruit.”

Whiting noted that, “You started adding new tiers of horizontal fruiting wood between the wires, and permitted some of the third level of branching off the trunk.”

Yields in the block have been strong, Anderson said.

“For the four-year average, starting in 2016, we’ve averaged 15.5 tons per acre, with a high of 19 and a low of 10.”

“That’s 42-43 tonnes per hectare for those of you on meters, which is tremendous,” Whiting said. “The initial reaction to that might be (what is the) fruit quality? As I stand in here and look at it, the size is very good.”

“Surprisingly, the size has been there,” Anderson said. “I don’t think the taste has necessarily been there. Our target these days is more of the 12 to 13 tons. This looks like its more like 13 tons. The predicted peak size of the fruit is 9-row.”

“Walking up and down here, from what I see, it’s a great combination of quantity and quality of fruit,” Whiting said.

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Strategic wood placement

Anderson said that by strategically placing extra wood, “we’ve basically doubled the fruit-surface area the way this system is set up. Through trial and error, we’ve experienced that, if there’s space for it, and we need some surface area, we’ll just trim it down. On this Mazzard Sweetheart, it’s been fairly forgiving.”

Although Anderson hasn’t used the practice, Allan Bros. has applied Promalin to help fruit development. “I personally have not,” Anderson said. “We just have done the scoring.”

“Promalin, in combination with the scoring can lead to better breaks,” Whiting said. “Promalin treatments tend to be a little more sensitive to temperature. On a colder day, you don’t seem to get the biological response that you get in the uptake of activity with Promalin. On the flip side, in an orchard where they are trying to create the totory-style cherry training system, the V with horizontal fruiting wood, then you can use your fruiting potential on that early spur wood.

“This is a very popular structure these days – with leader that puts out horizontal fruiting wood. Bringing in additional fruiting wood has made a big difference in (this orchard).

“One of the clues that any grower can use is just to be out in the orchard,” Whiting said. “This is a good time of day. Just looking to the ground. We always look at the tree and the fruit quality and the vigor. But if you look to the ground, you see that shadow that’s cast. You can see fairly well we’re at times in full shade, and other times we’re in full sun and there’s still good light penetration to the base portions of the tree. Normally, when that doesn’t happen, your first clue is losing those spears in that bottom tier.”

— Gary Pullano, managing editor