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• On a good day, the Oxbo harvesters manufactured at Clear Lake, Wis., team in a pair, running along each side of a row of trees, then come in with 14 loads, replacing four 20-man harvest crews, says their inventor and operator, Tom Visser.
GROWERS USING the mechanical harvester are saving 25 cents to 30 cents per box, says Fritz Roka, University of Florida agricultural economist. “We’ve documented that it saves money.”
Using canopy shaker
“The co-op has been mechanically harvesting 600,000 boxes a year, plus or minus,” he says. “We’re using the canopy shaker machine as opposed to the trunk shaker. It gets 80 percent to 85 percent of the fruit off the trees. We then follow with a gleaning crew, assuming what’s left has enough fruit value. We use that as support to our manual labor.
“The machine will get us over peak periods when we may not have enough labor. We’ve done it mostly on Valencias and some Hamlins. We find there’s too much mechanical damage to thin-peeled fruit, so this year we didn’t do any Hamlins. We just weren’t comfortable with that.”
Mechanical harvesting is possible without the abscission agent, as many growers already know, but the chemical should make the process easier, with less tree damage. Since it is so selective, next year’s Valencias, most at the pinhead stage during application, should not be affected.
Mike Murphy says he watches the machines closely during harvest, and if he sees too much loss of next year’s crop, he will stop mechanized harvest on that block.
“I do hope we get the chemical on the market,” Burns says. “With it, the grower will realize this can be done effectively and efficiently.
“About 70 percent to 80 percent of the crop can be removed without the abscission agent, but with the agent you’ll get 95 percent off the tree, in general. You can expect a 10 percent to 20 percent increase in fruit removal. With the agent, you can also harvest less aggressively and go faster down the row.
“With the machines we nowhave,the operators are not likely to make big errors. When we first started, yes, we sometimes pulled trees out of the ground. But we’ve learned a lot since then, and I’m pretty confident we know how to machine-harvest trees now.”
The abscission agent’s initial success, however, could depend on whether growers use it on trees slated for hand harvest.
“When work first started on the abscission agent,” says Mike Sparks, Florida Citrus Mutual’s chief executive officer and executive vice president, “we always had the question of whether it would be ready not only for mechanical harvesting, but also for traditional harvesting. Can it take all our growers to the next level?
“Here’s a technique, a protocol, a process that could assist us with our traditional needs for labor. If it could be advanced forward, how beneficial could that be as we address labor concerns in the future?”
Burns says the abscission chemical should make it easier for hand laborers to pick fruit. “I’m cautiously optimistic that it is going to be a very good thing for workers,” she says.
It adds another layer of management for growers, however.
“When it’s applied, the fruit is going to come off the tree,” Burns says. “A delay could be a big problem — you don’t want fruit on the ground. It’s a management procedure that growers are going to have to learn. The thing is, the abscission agent works, and it’s going to be a great tool when we get it in growers’ hands.”
Harvest expense runs about 27 percent of total cost of citrus production, Richardson says. That percentage is lower than it was several years ago, due to higher production costs relating to citrus greening disease.
On a 325 box per acre grove,the state average for oranges, the abscission agent paid off in as much as $200 per acre net cost savings, he says. Push production to 400 boxes per acre and savings could be as much as $330 per acre.
“That would be a net $80 million to $90 million a year in Florida. It would certainly help, with all the increased costs we’ve seen the last several years. Abscission is the key. It allows late season Valencia harvest and increases efficiency throughout early-, mid- and late seasons.”
All the pieces for mechanized harvest are finally just about in place. Whether they actually come together remains to be seen. Fritz Roka, for one, thinks success is tied with the fight against citrus greening disease.
“Four years ago, 35,000 acres, 7 percent of sweet orange acreage, was mechanically harvested. It was less than 10,000 this year. We’ve been losing tree vigor, so the trees haven’t been able to perform as well as we want.
“The technology for mechanical harvesting is here, and it works even without the abscission agent. But the disease is hampering us.”