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Planting a high-density cherry orchard, with its earlier production and potential for higher yields at maturity, is one of the options that growers should consider when thinking about replacing aging, less productive cherry blocks, according to an Oregon State University ­extension educator.

With today’s tight profit margins, profitability is tied to productivity, says Lynn Long,

OSU extension horticulturist for Wasco County. Long took part in a recent OSU study updating the ­economics of establishing and producing high-density cherry orchard ­systems.

“I’ve seen a lot of older orchards that are only averaging two to three tons per acre,” he said. “A lot of growers have no idea what their average yield is for each block. When you’re getting those kind of low yields, I don’t see how people can make a go of things.”

With low tonnage, growers must receive very good prices year in and year out, Long said. “But with cherries, it’s a given you’re not going to do that every year.”

To help growers increase productivity, OSU and Washington State University horticulturists have been studying new high-density training systems like the KGB (Kym Green Bush), a system named after its Australian developer, and the UFO (Upright Fruiting Offshoots), developed by WSU’s Dr. Matt Whiting. Both training systems are pedestrian-style orchards that allow for early high yields, but also high sustained yields because of increased light interception, Long said.

The UFO is a two-dimensional system, with rows closer together than standard density and upright shoots that result in a wall of cherries. The KGB, a variation of the Spanish bush system, also has tight rows. Both increase the amount of light interception.

Also, both systems use dwarfing rootstocks to bring precocity to the orchard, he said, adding that growers can achieve seven tons per acre in the fifth leaf.

High-density considerations

Long outlined some considerations of high-density orchard systems compared to standard density orchards:

Extra cost for dwarfing rootstocks. The Gisela dwarfing rootstocks cost about $3 more per tree than the standard Mazzard rootstock. Growers concerned about tree costs should consider using Krymsk 5 or 6 or Maxma 14, which cost less than Gisela rootstocks.

Improved exposure to sprays. Better spray penetration into the smaller tree canopies of high-density systems have the potential to improve pest and disease control.

Reduced pruning costs. Studies conducted by Long show reduced pruning costs in the KGB and UFO systems compared to standard systems, even though there are more trees per acre. This is because the techniques are simplified and every step uniform, which changes pruning from an art to a faster, repeatable process.

Reduced harvest labor costs. Higher density systems are picker friendly, with reduced or minimal need for ladders. In studies comparing harvest costs of high-density and standard systems, Long has found that a worker averages about 100 pounds of fruit per hour picking from trees on Mazzard rootstocks. In a pedestrian, high-density system without ­ladders, productivity goes up to 171 pounds per hour.

Preferred by workers. Cherry pickers in The Dalles, Oregon, find the work easier in high-density orchards than in standard orchards and love picking the smaller trees. Long predicts that during labor shortages, growers with standard density orchards will have greater difficulty securing pickers, while those with high-density orchards will have “pickers knocking on their door.”

Orchard management. The KGB is extremely simple to manage and establish. In Spain, pruning the Spanish bush is called “goat pruning” because even a goat could prune it, he said. The UFO, once established, is also very simple to maintain, although the first few years of ­training and establishment are critical. “But once it’s established, it’s a very easy system to maintain.”

Better quality fruit? Long has no data to back this, but has heard from field representatives that fruit quality is better on new high-density systems than from old, ­standard-density trees. “Especially if fruit experienced rain or some other stress or problem near or during ­harvest, fruit from young trees seem to be coming into the packing house in much better condition than fruit from older trees, and I’ve heard this from many sources for multiple years,” Long said.

Irrigation. Trees on Gisela rootstocks are less forgiving of mistakes made with irrigation than trees on Mazzard. He noted that most growers are familiar with how to irrigate Mazzard trees but may be unaware of the nuances with Gisela.

Tried and true

Is there a compelling reason to stay with the standard-density systems?

Growers feel more confident with the old, standard-density systems on Mazzard rootstocks, Long said. “Some believe managing a high-density system on semidwarfing rootstock of Gisela 6 or 12 is more difficult because of the potential for oversetting. I understand that.”

To avoid oversetting, he suggests staying away from vigorous rootstock/scion combinations like Gisela 6 and Sweetheart. Nonetheless, he’s been able to grow the G.6/Sweetheart combination under several high-density systems and maintain size in all seven years of the orchards’ productive life by using an expert pruning crew.

“But that’s why I like Krymsk rootstocks. They’re not quite as productive as G.6 or 12 and may be a good option for growers not comfortable with G.6,” he said.

When to replant?

Updated OSU economic studies show that most growers can’t afford to keep farming unproductive blocks. At four tons per acre—a level that Long believes many old blocks are below—a standard-density block must bring 85 cents per pound to clear about $300 per acre or 95 cents per pound to make a little more than $1,000 per acre.

“With midseason Bings, where most of The Dalles and many Washington growers fit, how often do you get 95 cents a pound?” he mused.

“You need to know what you’re averaging in yield and price and what’s going on in every block. And really pay attention to your older blocks.”

As blocks get older, growers must think about options for replanting. “If you’re ready to take that leap from a standard-density to high-density orchard, I’d suggest going with Krymsk instead of Gisela as a rootstock because of Gisela’s productivity concerns. Krymsk gives growers opportunity to try a productive semidwarfing rootstock with one that’s not as productive as Gisela.”

Greater risks

High-density systems offer returns earlier in the life of the orchard and have potential for higher annual yields. They are easier to maintain and faster to harvest, but the high-density systems require significant up-front costs and come with greater management risks.

According to the OSU economic study, it can take up to year eight in a high-density system before all of the ­previous years’ production costs are paid.

The Dalles cherry grower Mike Omeg cautions growers to fully consider and explore all the factors involved with high-density orchards before going that route. “I would not plant high-density unless it fits your management style,” he said. “There’s zero room for error, and you have to put too much money out there if you’re not prepared for the increased management.”

High-density systems on dwarfing rootstocks are less forgiving than standard orchards, the OSU study underlines.

“Improper management can mean small, poor quality fruit, and poor pruning can lead to excessive shading and spur death, and lack of vigor can increase pest and disease attacks. For these reasons, it is important that growers properly evaluate the scion/rootstock choices in relationship to the proposed orchard site, while critically assessing their own management skills before deciding to plant a high-density orchard,” the report said.