Jim Schupp (on tractor) took an active role in evaluating the Darwin blossom thinner and considers it a key to peach profitability.
Photo by Richard Lehnert
Peach growers in Pennsylvania are being urged—by some convincing data—along a path that changes the look of their orchards and the methods they use to manage them.
Like apple growers, they are adopting planar canopies and higher densities and looking at new technologies, especially platforms, as ways to grow better quality fruit and cut the cost of labor to do it.
Most of the convincing data has come from Pennsylvania State University’s Fruit Research and Extension Center at Biglerville, where pomologist Dr. Jim Schupp works on orchard design. He and Adams County Extension Fruit Specialist Dr. Tara Baugher have collaborated on mechanization studies for more than five years.
At the Michigan Peach Sponsors’s annual meeting in Benton Harbor in March, Schupp explained how everything fits together.
“More than 60 percent of the cost of a packed box of peaches is labor,” he said. “Some would argue it is 75 percent. Now, it’s not just labor cost we have to worry about. It’s availability. We need both a workable guest-worker program, and we need to increase labor efficiency.”
Growers will not be able to do away with labor in growing peaches, especially in harvesting, he said, but use of machines like the Darwin string thinner and platforms will reduce the need for labor and allow less skilled and less physically robust workers to be part of the work force. “Even I can pick peaches from a platform,” Schupp said.
After several years of trials, Schupp and his colleagues have agreed they really like the orchard platform they purchased from the Italian company N. Blosi. It is self-propelled, contains a platform that moves up and down and in and out, and can be used for thinning, pruning, harvesting, and other tasks like applying mating disruption pheromones. It incorporates features that allow bins to be filled and offloaded, eliminating ladders from orchards.
In peach thinning studies, platforms have improved labor efficiency by 30 to 60 percent and cut costs by $128 to $285 per acre, Schupp said. Moreover, he said, there’s the intangible benefit that workers like them; platforms make work easier and less fatiguing.
Traditionally, peaches have been grown in an open-vase shape, several scaffold limbs emanating from the trunk in a whorl. The chief benefit was low, spreading trees that reduced ladder work. These trees are not suited to use of platforms and are more difficult to thin mechanically than more upright trees.
“What we’re looking for in a ideal orchard is a tall, narrow wall, two to three feet wide at the most, planted in rows 14 feet apart for vertical axis and 18 to 20 feet for perpendicular V,” Schupp said.
“In a wonderful synchronicity, the trees that are most labor efficient are also the most efficient biologically. The extent of light penetration into canopies is the same as the length of the human arm.”
Trees grown in an upright manner are taller, but with the use of platforms, the labor efficiency is about the same as for open-vase trees.
In one study, Schupp looked at thinning costs comparing ladder systems with platforms and open-vase trees with taller ones. First, they used the Darwin string thinner to knock off half to two-thirds of the blossoms. In the open-vase system, it cost just under $20 per acre to do follow-up thinning by hand—and no ladders or platforms were used.
Trees planted in the upright style of perpendicular V (two scaffolds), quad V (four scaffolds), or hex V (six scaffolds) cost around $40 an acre to thin if ladders were needed, but less than $20 when platforms were used. The platforms completely offset the disadvantage of the taller trees.
In an experiment now in its sixth year, Schupp is comparing the profitability of four different orchard systems: perpendicular V, quad V, hex V, and open vase. Here are some of his conclusions.
Yields have been the lowest with the open-vase system (about half of the best-yielding system). But fruit from open-vase system have been larger.
“Perhaps we need to prune the V trees harder to eliminate some of the small fruit,” he said. “Perhaps we have to adjust fertilizer practices, or perhaps we need to adjust the target goal down to growing 500 bushels per acre. We have a lifetime of experience with the open vase system. We are good at it.”
Another possibility is to add irrigation. A trickle irrigation system was added last year, but its effects have not been studied. Irrigation is seldom used in the Northeast.
One problem with the open vase was the 14- by 18-foot spacing took much longer to fill than narrower spacings. After five years, the open-vase trees had not filled their space, so he expects yields will continue to rise. The open vase was planted at a density of 173 trees per acre, the lowest tree density, and thus was the lowest-cost system to establish.
Costs and returns were similar among the four V systems. More trees cost more to plant, but filled their space faster and produced earlier. The perpendicular V was planted at 5- by 18-feet (484 trees per acre); the quad V at 7- by 18-feet (346 trees per acre); and the hex V at 10- by 18-feet (484 trees per acre).
Their ranking in order of profitability, high to low, was hex V, quad V, perpendicular V, and open vase.
“All these systems are winners,” Schupp said, “but some were better than others. While all four systems generated positive returns, the Vs were better.”
Key advantages of the high-density systems were early yields, simple pruning, and the ability to adjust to mechanization—both platforms and the Darwin blossom thinner.
The key disadvantages to high-density systems is tree height, requiring ladders or platforms, and somewhat smaller fruit.
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