The 58,000-pound mechanical harvesters pounding through groves outside Immokalee this spring gave a good look at the citrus industry’s possible future.

The ultimate winner may or may not look like them — but these are anything but test machines.

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.

An Australian, Visser has worked in Florida since 1993 to develop an effective citrus harvester.

Interest in mechanical harvesting of citrus goes back much further than that, however, at least to the 1950s. Whenever labor concerns peak, so does interest in mechanized harvesting, and the current immigration crisis that threatens to pinch the supply of citrus harvest workers has ramped up interest in the machines, although actual usage of the mechanical harvesters declined this year.

“Mechanical harvesting is absolutely feasible and economically necessary,” says Fritz Roka, University of Florida ag economist working at Immokalee. “We’ve documented that it saves money.

“Growers using it are showing that it saves 25 cents to 30 cents per box, even with the added cost of gleaning behind the machines. Growers of sound mind aren’t going to leave a single fruit out there; they will go back and get that 5 percent left in the grove.”

Growers concerned that mechanical harvesting stresses trees, making them more vulnerable to citrus greening disease, may have a valid point if the trees are already hurting, Roka says. He says that could be the reason some growers didn’t use the harvesters this year.

“We’ve got to bring these trees back to a healthy state. Research has documented over and over that whatever damage is done, a tree can rapidly overcome it and come back with a good crop the next year. The research is pretty good that the machine doesn’t adversely impact long-term tree health, if the tree is in good health to begin with.”

The machines add efficiency to harvesting at Cooperative Producers, Inc., groves near Immokalee and LaBelle. The co-op uses them to pick Valencia oranges, and is concluding three years of tests with an abscission compound that is likely to be paired with the machines, further increasing efficiency.

The mechanized harvest unit requires four trucks, or ‘goats’ — two with each machine. The machines, if purchased, would run about $1.3 million.

“With that kind of expense for the machines, you’ve got to run them,” Roka says. “You have to fill a lot of trailers to make them efficient. Anytime they’re interrupted, that puts a lot of pressure on these machines.”

They can be moneymakersin many situations. “How that efficiency equates to us, since we’re using a contractor, is that we had about a 30 percent savings over conventional harvesting,” says Mike Murphy, chief executive officer and executive vice president of Cooperative Producers.

After testing that began in the 1970s, the abscission chemical may finally be cleared in time to use it on the 2013 Valencia crop. The U.S. Environmental Protection Agency now has the compound under review and is expected to make its decision public in February.

Expect full registration

“We expect it to be a full registration,” says Taw Richardson, CEO and president of AgroSource, Inc., the company licensed to sell the as yet unnamed abscission agent. AgroSource has worked with the compound since 2004.

Tests show it may also find a place in hand-harvested groves, since it reduces the labor force needed to pick the fruit by as much as two-thirds, he said at the recent Florida Citrus Industry Conference at Bonita Springs.

“It can reduce harvester fatigue and improve productivity in hand-harvested groves as much as 50 percent,” Richardson says.

Jacqueline Burns, now director of the University of Florida Citrus Research and Education Center at Lake Alfred, spent much of her career working on harvesting issues, including the abscission agent.

“This chemical has been around for more than four decades,” she says. “It was originally a compound from Abbott Labs. In the 1970s, thousands of abscission agent compounds were screened, and this one stood out. It is so selective and so forgiving of errors in calculation. But it only works on citrus; its action is very specific to the citrus peel, and it has to be a mature fruit.

“Many growers haven’ttaken the plunge into mechanical harvesting, but have said as soon as we could get an abscission agent, they would try it. This is definitely a solution worthy of consideration; it has real value.

“It will help growers remain competitive and overcome a labor shortage. But, there is a tradeoff. If the tree is not healthy, mechanical harvesting might damage it. But a healthy well-watered tree should do well.”

Its selectivity worked against quicker registration of the abscission agent, she  says.

“We explored the concept with the big chemical companies, and the crop acreage wasn’t big enough to encourage shareholders to invest in an abscission agent that would only be used on citrus.

“We got a smaller company, AgroSource, interested, and they have shepherded it forward, along with the Florida Department of Citrus, the public entity involved in this public/private partnership that is now moving forward.”

The venture carries risk.

“In the case of most agri-chemicals, you’re talking huge volumes and economies of scale,” AgroSource’s Richardson says. “What we’re looking at doing is manufacturing one product for one crop in one state.

“We’ve only made it on a small scale, so when we get on a larger scale we’ll really find out the costs of making it. We need volume. And, there are questions. Are people going to move rapidly into this for manual harvesting? Or will the industry be buying it only for mechanical harvesting? We’re going to have to think about all these processes going forward.

“We’re trying to learn how quickly we can make this move and scale up manufacturing. You generally want a year to get manufacturing going, but we would like to catch the Valencia season next year. Understanding what needs to be done is critical. It would be a neat trick if we can get that accomplished between now and Valencia season next year, but if that doesn’t happen, we’re not going to give up.”

Extensive testing over many years gives researchers the ability to pinpoint what the abscission agent will do, Richardson says. “It has been used successfully around the state, and it’s pretty predictable if you follow the protocol on how to use it.”

Mechanized harvesting couldchange a number of things in the business, including how groves look, he says. He thinks the machines will continue to evolve, and that the best machine might wind up being an over-the-top harvester like the one used in grapes.

“Tree architecture, root stock and grove design will all change,” Richardson says. “We’ll have an advanced citrus production system, with trees on 8x15 foot spacings, 350 trees per acre — something very manageable. We have to think about where we’re going.”

From a large acreage grower’s point of view, changes like these look appealing if they ultimately lead to greater profit margins in a business that seems tougher each year. Frank Hunt, with Lake Wales-based Hunt Bros., part of the Cooperative Producers operation near Immokalee, likes the possibilities.

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.”