Peach growers pleased with mechanical thinning

Fruit grower Kevin Bittner has trimmed some of the work, and the cost, out of hand-thinning 100 acres of peaches. “We’ve cut our hand-thinning costs in half,” says Bittner, who has operated a mechanical blossom thinner for two seasons at Singer Farms in Appleton, N.Y. The thinner uses a spindle to remove peach blossoms, helping growers to manage fruit load and subsequent hand-thinning costs. “The mechanical thinner just makes it that much easier to get everything done.”

Mechanical blossom thinners are generating a per-acre labor savings from $462 to $1,490 for processing peaches and $264 to $934 for fresh market peaches.

Bittner was inspired by Penn State University’s Innovative Technologies for Thinning of Fruit project, which has been powered by federal grants, industry support, cooperators and growers in Pennsylvania, California, Washington and South Carolina. While the program has focused on peaches for three years, the hope is that results will deliver new cost-cutting options for other stone fruits, too.

The project’s findings include:

  • Blossom removal ranging from 17 to 56 percent.
  • A reduction of hand-thinning requirements by 19 to 100 percent.
  • Improved fruit size and yield because of decreased competition.
  • Per-acre labor savings from $462 to $1,490 for processing peaches and $264 to $934 for fresh market peaches.

“The immediate outcome of our research to date is that we’ve road tested the mechanical thinner, and we’ve established there’s no reason to wait – we can grow peaches with less labor,” says Jim Schupp, horticulturist at the Penn State Fruit Research and Extension Center in Biglerville, Pa.

The skinny on thinning

Schupp says that horticulture scientists have sought cost-cutting thinning solutions that were less labor-intensive, including chemical methods, for some time. When Katy Clowney, a member of Schupp’s team, attended a trade show in Italy in 2006, she saw a German-designed string thinner that effectively thinned organic apple blossoms.

Pennsylvania peach growers were eager to try the mechanical string thinner. Because it was designed to thin narrow, vertical canopies, researchers used the machinery with trees having perpendicular V or quadrilateral V systems. In 2008, a horizontal thinner prototype was tested on open-center or vase systems.

The 2009 prototype is a hybrid of a vertical rotating string thinner, with the ability to thin vase or angled trees and adaptability for varied orchard systems. The machine, known as the Darwin, is now commercially available in North America.

The current thinner is nonselective, although engineers at Penn State’s department of agricultural and biological engineering are developing selective thinners, says department head and Innovative Technologies Director Paul Heinemann.

“We’ve started with the nonselective thinner to document it really does work, and we’ve sought to refine it so that we get as close to the optimal result as possible,” says Schupp.

Innovative Technologies for Thinning of Fruit

  • Initiated at Penn State to develop and field test new mechanized methods of thinningspecialty crops and to establish feasibility for the market.
  • While the program has focused on peaches, there is increasing interest in developmentfor other stone fruit.
  • Researchers, extension professionals and growers participated.
  • Data collected from growers in four states.

Research supported by the USDA’s Specialty Crop Initiative, the California Canning Peach Association, the Washington Tree Fruit Research Commission, the State Horticultural Association of Pennsylvania, the South Carolina Peach Council, and the Pennsylvania Peach and Nectarine Board.

Lots of variables

In each participating orchard, the benefits of thinning vary based on multiple factors, including variety, orchard configuration, tree orientation and seasonal influences.

In Bittner’s case, the trees at Singer Farms are pruned so that peaches are harvested from the ground. His orchards are being designed to match the mechanical blossom thinner’s adaptability.

The orientation of trees in older orchards gives some growers pause.

“As long as you have a strong bloom and you are feeling brave enough to take fruit off, there is no question that it improves the size of the fruit and reduces hand-thinning cost of the green fruit,” says Bruce Hollabaugh, production manager at Hollabaugh Brothers, Inc. in Biglerville, Pa. He is a supporter of the mechanical blossom-thinning project. The 500-acre orchard includes about 75 acres of peach trees.

“One reason for hesitation in adoption of these things is cost, but change to the orchard structure and tree system is another great requirement. You have to have the right structure to optimize the tree thinner,” he says.

N.M. Bartlett, Inc. in Beamsville, Ont., produces the Darwin thinning machinery in North America, and cost has been estimated around $12,000.

“I’m able to see the benefit, and I’ve proven it on my farm and I’ve seen it at Penn State,” Hollabaugh says. “But, I have to be careful that I’ll be able to use enough acres to see the benefit on the back side.”

Growers say it takes a lot of energy and concentration to regulate the thinner between trees and monitor how many blossoms are being removed.

Next Gen Thinners in DevelopmentWould Further Reduce Labor, Cost

If you can imagine a mechanical blossom thinner that employs robotics to pick andchoose which blossoms to thin on a stone fruit tree, you have caught the vision of aresearch project at Penn State University.The Innovative Technologies for Thinning of Fruit program has enabled the introductionof a German spindle-based thinner to peach orchards in four states, easing itscommercial introduction in North America and cutting labor costs for participants.The machinery is manufactured by N.M. Bartlett, Inc. of Beamsville, Ont., and soldthroughout North America.

The program received a $2 million federal grant under the Specialty Crop ResearchInitiative, as well as industry association support and participation from cooperatorsand growers to establish the thinner’s potential.

The nonselective thinner is the current standard, but as Paul Heinemann explains,there is lots of opportunity in the technology’s optimization.

“We’d like to fully automate the project with a selective thinner that would choosewhich blossoms to remove using robotics and machine vision,” says Heinemann, headof Penn State’s department of agricultural and biological engineering and projectdirector. “There is so much variability it is somewhat of a challenge. When you put thisin an orchard, there are so many hurdles to cross.”

Success of the mechanical thinners has been well documented by the project since2007, with dramatic reductions in labor costs for hand thinning. Research has alsodocumented increased fruit size in many cases.

Starting with the nonselective model designed in Germany for organic apple blossoms,Penn State’s researchers introduced the mechanical thinner with a verticalspindle in 2007. A hybrid version is now in use that can also thin the tops of treeshorizontally. The thinners attach to the front of a tractor.

Heinemann says his team is testing another nonselective thinning prototype withsensors that would adjust the thinning spindle automatically, making it easier foroperators to maneuver between trees.

He says, “I’d say it’s probably a year before it would be in any commercialoperation.”

Putting it to work

The Darwin PT-250 mechanical blossom thinner is used by Matt Peters of N.M. Bartlett, Inc. on peach trees trained to an open vase system in Niagara-On-The-Lake, Ont. The machinery was used on both sides and then on top to thin blossoms. The Darwin also thinned the nectarine trees in the next row with two passes. The machine, manufactured in North America by Bartlett, is central to research on blossom thinning for stone fruits.

Horticulturist Jim Schupp, of Penn State’s Fruit Research and Extension Center in Biglerville, Pa., uses a mechanical blossom thinner to reduce peach blossoms. Research by the university, other educators, industry associations and cooperators has established that the thinners can significantly cut hand-thinning labor costs.

Clowney, who is now the sales and marketing assistant and agriculture tech specialist at Bear Mountain Orchards in Aspers, Pa., is among several who operate the string thinner on-site. As an original test site for Penn State’s research program, the orchard was among the first to buy a mechanical thinner and now owns two.

“This definitely increases fruit size,” says Clowney. “We’re a big packer, but we also have a large crate trade, so when we go through and pick peaches we are looking for that 2.75 to 3-inch peach. We are able to pick those specifically for the crates.”

Overall, the thinning has produced a more consistent peach crop as well, Clowney says.

“One of the reasons the crop size is more consistent and uniform is that you are reducing competition early on. You get a better peach all around,” she says.

In the Southeast, the most popular benefit of thinning has been reduced labor costs and increased flexibility with workforce.

“We’re still seeing whether it works in practice as well as theory,” says Greg Henderson, Edgefield County extension agent for Clemson University.

Katy Clowney, the sales and marketing assistant and agriculture tech specialist at Bear Mountain Orchards in Aspers, Pa., had not driven a tractor before operating one with a mechanical blossom thinner attached to the front. Growers say that using the thinner requires energy and concentration, as well as adjustments to the spindle as needed.

“We’ve had positive results in labor savings – a great reduction in man hours and some nominal increase in our fruit size,” Henderson says. “We’re trying to get the right combination with bloom removal … the machine can’t replace the human hand and eye, and it’s going to require a great deal of assessment,” he concludes.

Jennifer Paire is a freelance writer based in Canton, Ga.