planted with 70–100 trees/ha. After World War II, rural migration increased production costs, and mechanical harvesting became compulsory. Since then, these plantations have begun to be replaced by high-density mechanically harvested orchards. Rain
In recent years, the increasing consumption of olive oil has boosted the planting of intensive and superintensive orchard systems to achieve competitive production costs ( Arbonés et al., 2014 ). Continuous mechanical harvesting is a key management
costs as compared with production in the United States. Red chile production labor costs were reduced to ≈10% ( Eastman et al., 1997 ) when the crop was transitioned to mechanical harvest. If green chile production shifted to mechanical harvest, like red
). The only realistic solution is to develop economically feasible mechanical harvesting. Mechanical harvesting has three components. The first is a harvesting technology able to remove and catch the fruit without economic damage to the crop or tree. The
/or market demands. Mechanical harvesting fresh-market apples has been studied since the 1970s, but it has proven difficult to develop machinery that can efficiently harvest fruit without bruising ( Sarig, 1993 ; Zhang et al., 2016 ). Only recently have
Field experiments were conducted to investigate the effect of sprayer type, airflow rate, and nozzle output on deposition of active ingredient and mechanical harvesting of `Valencia' orange (Citrus sinensis). Fruit detachment force (FDF) and percentage of fruit removal (PFR) by trunk shaker were used as mechanical harvesting parameters. A PowerBlast sprayer discharging radially and a Titan sprayer discharging over the entire canopy were used. The spray mixture contained an abscission chemical (CMN-pyrazole), a surfactant (Kinetic) and a fluorescent tracer (Pyranine-10G). Deposition was determined at three different heights outside and inside of the canopy. With the PowerBlast, higher airflow and lower nozzle output reduced deposition of the active ingredient. The mean FDF of sprayed treatments was less than that of the non-sprayed control but the difference among the four spray treatments was not significant. The lower airflow rate with lower nozzle output had higher PFR than that of the control. With the Titan sprayer, the mean deposition at lower airflow was similar to or higher than the higher airflow. At higher airflow, the lower nozzle output gave higher mean deposition. The Titan sprayer treatments resulted in less FDF than the control. At both airflow rates, the FDF was less at lower nozzle output than at higher nozzle output. The PFR of these treatments were not different from that of control.
An abscission agent [5-chloro-3-methyl-4-nitro-1H-pyrazole (CMNP)] was applied to `Hamlin' and `Valencia' orange (Citrus sinensis) trees at concentrations ranging from 0 to 500 ppm in a volume of 300 gal/acre. Four days after application, fruit were mechanically harvested with either a trunk shake-and-catch or a continuous canopy shake-and-catch system commercially used in Florida. Harvesting conditions were varied by limiting the actual trunk shake time of the trunk shaker to 2, 4, or 7 seconds, or by altering the ground speed of the canopy shaker (1.0, 1.5, or 2.0 mph). In general, increasing duration of shake and the application of CMNP increased percent mature fruit removal and decreased the amount of fruit remaining in the tree. Increasing CMNP concentration decreased fruit detachment force but increased post-spray fruit drop. Comparison of short duration shake times in CMNP-applied trees with trees harvested at longer durations either sprayed or not sprayed with CMNP indicated no significant difference in percent mature fruit removal. The results demonstrate that CMNP application increases harvesting capacity of trunk and canopy shakers by reducing time necessary to harvest each tree while maintaining high percent mature fruit removal.
., 2009 ; Youssef et al., 2011 ), although we may speculate that those which are not indicated originated from rain-fed orchards. There are almost no such studies of fruit originating from modern, irrigated, and mechanically harvested orchards, although
was followed by a number of additional trials performed by chile growers, processors, and small-scale equipment manufacturers who implemented their own designs or improvements on subsequent designs to strive for more efficient mechanical harvest
lacks large commercial-scale fruit production systems and the labor force and skillset that come with them ( Thilmany, 2001 ). Recognizing the need for a mechanical harvest system that could function in Washington cider apple orchards and the potential