A lot of shakin’ going on

11/01/2009 01:00:00 AM
Renee Stern

An abscission spray that leaves immature fruit on the tree promises to shake up mechanical harvesting in Florida’s citrus crop.

Meanwhile, Southern blueberry growers aiming for the fresh market are taking notice of mechanical harvesters for their fruit. Machine improvements and firmer-fleshed berry varieties from breeding programs may help tip the balance.

But industry representatives say that still-high fruit prices for both crops provide less incentive to switch from hand-harvesting. At the same time, ongoing concerns about labor availability keep interest high in mechanical harvesters.

‘A remarkably selective’ compound

Florida citrus growers found sufficient harvest workers this year, but labor costs remained at near-record highs, says Jackie Burns, interim director of the University of Florida’s Citrus Research and Education Center in Lake Alfred. Cost is the industry’s driving force behind mechanical harvesting, she says.

No more than 10 percent of the state’s total citrus acreage now is machine-harvested, Burns says. The advent of an abscission agent to loosen mature fruit but leave the rest could change those figures dramatically.

She and other researchers have developed “a remarkably selective” abscission compound, CMNP, that may receive an experimental use permit in a year or two for limited application.

“Abscission is not necessarily the silver bullet, but it is the next big step,” says Paul Meador, president of Everglades Harvesting & Hauling Inc. in LaBelle, Fla.

Without it, growers can harvest only part of their crop with machines, and must return to hand-picking in May and June to avoid shaking off next season’s immature fruit, he says.

For now harvesting machines must be supplemented with hand-gleaning to recover fruit that falls to the ground rather than into trailers. That added labor increases mechanical harvesting’s costs significantly, Meador says.

Fruit prices have remained high enough to support those costs, but any drop in the market may make hand-picking the whole crop more attractive, he says.

Fritz Roka, associate professor of agricultural economics at the University of Florida’s Immokalee Research and Education Center, estimates a machine-and-abscission harvesting combination could cost as low as 75 cents per box. Hand-picking runs about $1.80 to $1.90 per box. “That’s a significant difference,” he says.

Without the use of an abscission agent, recovery rates for commercial harvesting machines—75 percent to 80 percent—aren’t yet optimal. “That much [loss] we can’t ignore,” Roka says.

The best gleaning crews can bring that figure up to about 98 percent of the crop, close to hand-picking rates while costing 20 to 30 cents per box less, he says.

Abscission’s potential to reduce the amount of gleaning necessary could alter that equation.

Changes in tree and grove architecture as well as machine improvements could help raise recovery rates, Roka says.

“It’s all about capacity and improving the total boxes harvested per season,” he says. “Anything that increases capacity will drive down the unit cost.”

“If there are no major changes to the machines, growers or harvest contractors might be reluctant to invest in a harvester,” Burns says.

Photo courtesy of BEI International
BEI’s newest blueberry harvester, the Black Ice, uses jets of air to knock berries off bushes.

“We’ve stagnated on the efficiency of the machines,” Roka says. “There haven’t been improvements in seven or eight years.”

Also ripe for improvement is debris reduction. The force now needed to shake off fruit brings down leaves and branches in amounts that draw processor complaints. Applying an abscission agent could cut debris loads through reduced shaking force, he says.

Machinery trends in blueberries

Southern blueberry growers are seeing a flurry of new and improved harvesting machines, but fresh-market fruit prices and concerns about fruit quality mean many still stick with hand-picking.

Photo courtesy of the Agricultural Research Service
Twelve-foot-long nylon rods rotate and shake tree foliage to remove the fruit. The rods are part of a U.S. Department of Agriculture prototype harvester.

Breeding programs focus on southern highbush varieties with firmer flesh that bruises less easily, says Gerard Krewer, small-fruit specialist at the University of Georgia in Tifton.

Under the right weather conditions, rabbiteye varieties hold up well to mechanical harvesting for the fresh market, but southern highbush varieties generally are too soft, Krewer says.

Also important in evaluating new releases are a concentrated ripening period to reduce the number of harvesting passes, strong root systems that hold up to harvesting machines and fruit that detaches easily with limited ground loss, he says.

Pruning can correct a tendency toward low, spreading branches that hinder mechanical harvesters, but breeding a variety that grows more upright would limit pruning needs.

And, of course, the fruit still must appeal to consumers, Krewer says.

Alto Straughn, owner of Straughn Farms in Waldo, Fla., worked with Florida and Georgia researchers to test releases from their breeding programs last year. He called the results encouraging. For now, Straughn relies on hand-picking his fresh-market berries and machine-harvests for the frozen market. Labor availability will be the overriding reason for fresh-market growers to switch.

“I have five [mechanical] harvesters,” Straughn says. “Why? Insurance.”

But quality issues resulting from both improved varieties and machinery also will play a role, he says. His ideal is losing no more than 5 percent of the packout to softness and other sorting qualities, along with keeping ground loss in the field to no more than 5 percent.

Improvements aid harvesters

Oxbo International Corp.’s Korvan division and BEI International both produce berry harvesters with improvements in the works.

BEI’s newest model is the Black Ice touchless harvester, which uses jets of air to knock berries off bushes, says Rick McKibben, vice president of the South Haven, Mich., company. “It’s much gentler on the fruit,” he says.

The company also offers a new Centipede Scale catching frame that increases fruit capture while reducing bush damage, McKibben says.

Oxbo, headquartered in Clear Lake, Wis., offers two Korvan models for Southern blueberry growers, the 8000 and 7420 harvesters. The company has reduced drop distance on the 8000’s catch frame to retain as much bloom as possible on the berry, says Scott Korthuis, berry market manager.

Similar improvements to the 7420 are coming. An improved catching system is also under development, aiming to lower ground loss and boost yields, he says.

“The biggest area to save money [from reduced fruit loss] is in dropping,” Korthuis says.

ContactThe Grower at vlboyd@att.net or (209) 571-0414.



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