Mechanical Harvesters

A number of California tree fruit industries utilize trunk shakers for thinning and harvest, and research is focusing on evaluating and adapting trunk shakers for use in table olives. Moreover, trunk shakers used in countries such as Spain, Italy and Israel to remove olives for the oil industry are currently being evaluated for fruit removal efficiency. The typical trunk shaker is designed to produce rapid horizontal trunk displacement by clamping the trunk just above the soil line and applying a burst of energy. However, previous work with olive has shown that horizontal displacement applied at the trunk does not efficiently transmit detachment energy to small, immature fruit born on long, willowy branches of the olive canopy. More efficient fruit removal with trunk shakers may require additional canopy pruning to maximize energy transfer within the tree.

Canopy shakers can deliver both vertical and horizontal energy using tines that ‘tease’ fruit directly from the canopy. A local olive grower and manufacturer from the San Joaquin Valley has been modifying a Korvan canopy shaker and harvesting olives for market. In conjunction with our collaborative research group, fruit removal and final product quality is being assessed using this canopy shaker. Fruit removal with a canopy shaker of this type may improve in orchards with hedge-rowed trees.

A novel mechanical harvester is currently being tested at California State University, Chico, using pulsed bursts of high-velocity air to detach fruit. Since the machine does not come into physical contact with the canopy, it may reduce both tree and fruit damage. No matter which mechanical harvester(s) is ultimately used, a catch-frame is necessary to catch and convey fruit to a collection container for transport to the processing plant. Trunk and canopy shakers evaluated to date have catch-frames that satisfactorily catch machine-removed fruit. With refinement and further testing, these harvesting technologies provide the California table olive industry with promising alternatives to conventional hand harvesting.

The DSE700 canopy-shaking harvester in an orchard prior to harvest.	Spiked drums of the harvester interact with the olive tree canopy.
	photos by Louise Ferguson

Fruit Loosening Agents | Overview