Abscission agent, new rigs may boost citrus mechanical harvesting

12/05/2011 07:51:00 PM
By Tom Burfield

“Without abscission, selectivity becomes a real problem when you get to Valencias,” Meador says. “It’s held us back from mechanizing further.”

Currently, growers must suspend mechanical harvesting around May 10 because the process removes too much of the green fruit, says Carson Futch, whose company, P&H Solutions Inc., serves as the mechanical harvesting consultant for Johnson Harvesting Co. in Wauchula.

The agent will allow mechanical harvesters to run for an additional 21 to 30 days, making them more efficient, he says.

It also will enable growers to be less labor dependent in the spring, when workers often move out of Florida and on to other growing regions.

In addition, the abscission agent will help early in the season, when the fruit holds especially tight to the trees.

“It will shine for us early and late,” Futch says.

The fruit removal rate could increase up to 15 percent by using the abscission agent, says Fritz Roka, associate professor and agricultural economist at the Southwest Florida Research and Education Center in Immokalee.

Since the compound causes scarring in the form of a cosmetic ring on the blossom end of the fruit, it’s only used for processing oranges, not fresh varieties, Burns says. But she is hopeful that the effect can be reduced, and eventually it will be available for fresh fruit.

An added benefit

Tim Spann, assistant professor in horticultural sciences at the Lake Alfred center, has found what appears to be an unintended benefit of an abscission agent in the mechanical harvesting system.

Using machine picking removes up to 250 percent more leaves, stems and dead branches than hand picking, he found. An abscission agent reduces the amount of debris to levels equal to or less than hand picking.

“An abscission agent would really knock that back,” Burns says.

It’s difficult to anticipate how much the compound will cost, but Burns says, “We believe that it will be manageable.”

Registration should be complete within the next year or so.

Smaller machines

Meantime, Reza Ehsani, associate professor of agricultural and biological engineering at the Lake Alfred center, says only about 7 percent of growers use mechanical harvesting methods. But that could change as growers switch to high-density dwarf trees.

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