To meet increasing consumer demands for healthy, high-quality fruit, commercial growers in the United States are ramping up production of blueberries. Domestic production of this tiny antioxidant-packed "super food" has increased in seven Southeastern states, accounting for almost one-third of the U.S. acreage of two of the most popular types of blueberries.
Looking for ways to maintain blueberry quality while keeping production costs low, researchers at the United States Department of Agriculture (USDA) turned to the "V45". A mechanical harvester originally developed in 1994 to process blueberries in Michigan, the "V45" was named for its "V" shaped, 45-degree-angled cutting tool. The V45 features an innovative cane-dividing and positioning system and cushioned surfaces for catching delicate berries. The once-experimental machine was proven to be effective as a commercial harvester for northern highbush blueberries in Michigan, but until recently had not been widely used by growers of southern blueberry cultivars.
Dr. Fumiomi Takeda, Research Horticulturalist and Lead Scientist at the USDA Agricultural Research Service, and a team of researchers published their findings of the V45 study in the January 2008 issue of HortTechnology. The study was performed in Georgia to evaluate harvest efficiency and fruit quality of the V45 harvester on specially pruned rabbiteye and southern highbush blueberry crops. Takeda noted that northern and southern highbush blueberries are most often grown for the fresh fruit market and are almost exclusively hand-harvested. Highbush berries are of higher quality and have a longer shelf life than rabbiteye blueberries, which are often machine-harvested in June and July.
According to the report, harvesting highbush blueberries is labor-intensive, requiring up to 520 hours of labor per acre. With labor costs projected to rise while fruit prices are expected to drop as the blueberry industry expands in areas of the southeast U.S. and California, researchers are looking for ways to develop mechanized harvesting system for southern highbush and rabbiteye blueberries that retains the fruit's fresh-market quality.
To study the effects of mechanical pruning techniques on fruit yield, blueberry bushes were pruned to remove 30% to 50% of the canopy and open the middle, resulting in V-shaped plants of rabbiteye and southern highbush blueberries. Researchers discovered that yields of winter-pruned 'Brightwell' rabbiteye blueberry were lower compared with unpruned plants during both years, but winter-pruned 'Powderblue' rabbiteye blueberry plants produced as much as unpruned plants in 2005. In 'FL 86-19' southern highbush blueberry, plants that were summer-pruned in June produced as much as unpruned plants the following year, but plants that were winter-pruned in February had lower yields than unpruned plants the same year.
To reduce labor requirements and the cost of harvesting fruit produced for processing, effective power pruning and hedging equipment and mechanical harvesting systems are critical. Takeda explained the significance of the research, stating: "We found that V45 has the potential to mechanically harvest some rabbiteye cultivars while maintaining quality approaching that of hand-harvested fruit. Improved V45 mechanical harvesting system for blueberries in Georgia can help to reduce cost of harvesting and relieve potential labor shortage because of stricter immigration laws."
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