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After four years of collecting data, Penn State University horticulturalist Dr. Jim Schupp has arrived at some conclusions about how peach growers should grow peaches to make the best possible returns.

“All our systems made money, but some made more than others,” he said of the trials comparing four styles of plantings and two varieties.

In his trials in peach orchards planted in 2007, he’s found that the best orchard designs are the hex V planted on a 10- by 18-foot spacing or the quad V planted at 7 by 18.

To generalize, Schupp found that these two tall, upright V systems had the highest yields and the best-colored fruit, but not the largest fruit. But scaffold number affected yields—the larger number of scaffolds on the hex V and quad V systems yielded more.

The reason for the higher yields appears to be because the trees fill their space more quickly, he said. The open vase system, which had the lowest yields, took longest for trees to fill their space.

“The V systems have filled their space and may have peaked in their yield per acre,” he said during a session at the International Tree Fruit Association’s Boston meeting earlier this year. “The open vase trees still have more than two feet to go to fill the space, and I expect their annual yield to keep rising.”

Why do the V systems perform better?

“They have more linear bearing surface per acre,” Schupp said. “They have better light interception. Moreover, peach trees are naturally upright, so the V training is compatible with their natural growth. When pruned, they respond less  aggressively, with less retaliatory growth. And they don’t shade themselves excessively.”

For his trials, Schupp looked at the traditional variety Loring and a newer variety from USDA called Sweet-N-Up, which is an upright tree rather than a spreading one. The trees were trained in one of four ways and were evaluated for tree growth, yield, precocity, fruit size, fruit color, canopy light penetration, and labor efficiency.

Tree spacing

The four training systems generated tree densities from 172 to 484 trees per acre.

The open vase training system was planted at a spacing of 14 by 18, or 173 trees per acre, and usually had from three to six scaffolds per tree. In this training system, the central leader is removed early and scaffolds develop somewhat flat, making the trees shorter and wider.

The hex V system was planted at 10 by 18 feet, or 242 trees per acres, with six scaffolds per tree.

The quad V system was planted at a 7 by 18 spacing, or 346 trees per acre, and had four scaffolds per tree. The perpendicular V system was planted on a 5 by 18 spacing, 484 trees per acre, with two scaffolds per tree.  In the V systems, the scaffolds are tall, up to 14 feet, and upright.

In evaluating profitability, not only yield and fruit quality (and thus fruit price) was considered, but also how much work could be mechanized and how much labor needed to be expended. In all the trials, the Darwin string blossom thinner was used in three passes per row—two on the sides, one over the top—and followed up by hand thinning as needed.

A platform from N. Blosi was used in thinning, placement of mating disruption dispensers, summer pruning, and in harvest. The platforms eliminated the need for ladders in the orchards, reducing labor costs for pruning and thinning tall trees to levels comparable with what is needed in the pedestrian-size open vase system, where only short stepladders may be needed to reach the treetops.

Irrigation was added in 2011 and used during the final swell stage for the last two years.

Performance

Both the hex V and the quad V systems performed best, with the quad producing higher yields earlier. Given how frequently peach growers change to new, higher valued varieties, earlier production allows a grower to take advantage of a hot new variety faster, Schupp said.

It’s also easier to get four good scaffolds on a tree than to get six, he said. Still, it took fewer trees to fill an acre with six-scaffold trees, meaning investment in trees was lower.

On a yield-per-tree basis, hex V was a clear winner. In 2012, Loring peaches yielded just less than 2 bushels per tree in the open vase system, about 2 in the quad V system, and about 2.75 in the hex V system. The lowest yield per tree was in perpendicular V, about 1.25 bushels per tree, but this system has the most trees per acre.

In all the V systems, Schupp found it “challenging” to keep the scaffolds in a row. “Adding more scaffolds per tree did little to reduce tree height,” he said.

Schupp used a special scanner that objectively measured the amount of blush on a peach’s surface, using an anthocyanin index. Open-vase Loring peaches were about 18 percent blushed, while those from hex-V-shaped trees were 45 percent blushed.

The differences in uprightness between the two systems and the two varieties were assessed by measuring the cross-row canopy width. The upright, Sweet-N-Up variety was from one to two feet narrower than the Loring in any of the designs.

Sweet-N-Up trees in open vase, for example, were 11 feet wide while Loring was 12. In perpendicular V, the Sweet-N-Up canopy was 8 feet wide compared to nearly 10 for Loring.

Growers who choose to plant the Sweet-N-Up variety can plant them in narrower rows—and probably should. Yield per acre is directly related to how much light can be intercepted, Schupp said.

Sweet-N-Up trees were taller than Loring by only one to two feet. Open-vase Loring were just less than 11 feet tall, Sweet-N-Up just under 12.

Larger peaches

The open-vase system produced larger peaches, but also a wider distribution of peach sizes. The peaches on the V systems clustered at around 3.25 inches in diameter, with most in the range from just under 3 inches to 3.5 inches.

The open vase peaches put similar amounts of peaches in all size categories from about 3 inches to 3.75 inches, but more of them in the size range from 3.5 to 3.75 inches than any V system.

After four years of picking (2009-2012), cumulative yields of Loring peaches were about 975 bushels per acre in open vase, 1,500 bushels in perpendicular V, 1,610 bushels in hex V, and 1,700 bushels in quad V. But of those bushels, the quad V system produced the most bushels in the over-3-inch size category—just over 600 bushels, an amount nearly matched by hex V.

While more of the open-vase peaches were larger as a percentage, just over 500 bushels were 3-inch-plus. The perpendicular V system produced about 475 bushels of the 3-inch-plus peaches. Sweet-N-Up produced fewer large peaches than did Loring, no matter what the planting system.

Bottom line: An acre of open-vase Loring peaches generated $14,346 in cumulative value over the four crop years, the poorest of the four systems. Perpendicular V did only somewhat better—$18,579. Hex V did best—$27,120—and quad V second best—$25,886.

For Sweet-N-Up, values were lower across the board, but the systems produced at levels comparable with Loring. Open-vase Sweet-N-Up peaches generated $8,963 in cumulative value, perpendicular V $10,687, quad V $16,680, and hex V $19,685.