Harvest of Southern Highbush Blueberry with a Modified, Over-The-Row Mechanical Harvester: Use of Handheld Shakers and Soft Catch Surfaces

Abstract

Fresh market southern highbush blueberries are typically hand-harvested which requires an extensive labor force over a relative short period of time. With rising production costs and labor availability issues, interest in mechanical harvesting options is increasing. In 2017, an over-the-row (OTR) harvester was modified to reduce purchase cost while making hand labor more efficient. The picking heads were removed and dual worker stations were added on each side of the unit. Handheld olive shakers were suspended at each station. Experimental catch plates were installed on one side of the OTR harvester and soft, inclined surfaces over the rigid conveyors on both sides. ‘Meadowlark’ and ‘Farthing’ blueberries were harvested with this system and compared to those manually harvested by a commercial harvest crew. Samples from each harvest method were then commercially cooled and mechanically harvested fruit were commercially packed to determine packout data. Fruit firmness, bruise severity and composition were determined after one day at room temperature (22 °C) and after seven and fourteen days of storage at 1 °C. Average packout was very high for mechanically harvested fruit, 87% for ‘Meadowlark’ and 91% for ‘Farthing’. Initial firmness of both cultivars was lower for mechanically harvested fruit (208 g/mm) than hand-harvested fruit (243 g/mm). Fruit from the three treatments softened during storage, and although ‘Meadowlark’ remained firmer than ‘Farthing’ during storage, there were no differences due to catch surfaces. Hand-harvested fruit had no severe bruising (>20% of cut surface area) at harvest, increasing to 2% after seven days, while mechanically harvested fruit from both fruit collection surfaces had 3% initial severe bruising that increased to 22% during storage. ‘Farthing’ had slightly higher soluble solids content and significantly higher total titratable acidity compared to ‘Meadowlark’. Additional modifications must be made to the next-generation OTR harvester to further reduce blueberry harvest and handling impacts.