Precision pruning can help machines safely, efficiently harvest apples

A shake harvester being tested in the field.
A shake harvester being tested in the field. Apples are caught on rows of foam-padded shelves, and harvesting devices are calibrated so they don't damage trees.

With more apples to pick than any other state—more than 2.5 million tons every year—Washington apple producers have a growing desire to put labor-saving machines to work at harvest.

Sharing new discoveries on how precise pruning could support a labor-saving mechanical harvesting technique, scientists at Washington State University have won an award for their research from the American Society of Agricultural and Biological Engineers (ASABE).

Partnering with scientists in horticulture and biological systems engineering at WSU and Pennsylvania State University, lead author Xin Zhang, a doctoral student at WSU’s Center for Precision & Automated Agricultural Systems (CPAAS), published “A Precision Pruning Strategy for Improving Efficiency of Vibratory Mechanical Harvesting of Apples,” in the October 2018 issue of the ASABE journal.

Selected for ASABE’s 2019 Superior Paper Award, the authors were recognized on July 8that the society’s annual international meeting in Boston.

Supporting the state’s $2.4 billion apple industry, scientists at WSU have been exploring how machines can quickly shake apples out of trees, then safely catch and harvest them.

In the paper, researchers detail their study on how pruning affects efficiency and fruit quality for these vibratory harvesters. Testing precision pruning strategies on randomly selected branches of “Scifresh” apple trees in a commercial orchard, they found that pruning trees’ fruit-bearing branches so that they are short and strong can achieve optimal efficiency, while maintaining fruit quality.

Shake-and-catch technology has been successful in harvesting fruit for processing. Growers now seek to perfect this approach for fresh-market apples.

“The success of our system will reduce the demand for seasonal, semi-skilled labor, and the injuries associated with ladder use and repetitive motion, leading to a huge positive impact on economic and social sustainability for the U.S. apple industry,” Zhang said.

Closeup of Matthew Whiting, Qin Zhang, Xin Zhang, and Manoj Karkee in hallway.
A team of WSU scientists have won national recognition for their research into labor-saving mechanized apple harvest. From left to right are Matthew Whiting, Qin Zhang, Xin Zhang, Manoj Karkee.

The team’s discoveries show that a simple pruning technique can dramatically boost new harvest technologies.

“More importantly, it shows that research and development of any new technology for tree-fruit agriculture should be pursued closely alongside the optimization of the target crop and its canopy architecture,” Zhang said.

“We’re honored to receive this award, which recognizes that our efforts are valuable and meaningful,” she added. “We plan to continue refining the interaction between machines and crops.”

Co-authors included Long He, assistant professor of agricultural and biological engineering at Pennsylvania State University; Yaqoob Majeed, WSU doctoral student in CPAAS; Matt Whiting, professor in the WSU Department of Horticulture; Manoj Karkee, associate professor in the WSU Department of Biological Systems Engineering; and Qin Zhang, professor and director of CPAAS.

ASABE is an educational and scientific organization dedicated to the advancement of engineering in agricultural, food, and biological systems. Society members select papers published within their technical community for Superior Paper awards for timeliness, value, originality, benefits to society, and the quality of writing.

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