Mechanical harvesting of citrus fruit for juice processing from large-scale commercial plantings in Florida has economic advantages ( Roka et al., 2008 ) over hand-harvesting, especially when adequate seasonal labor is not available ( Brown, 2005
Juan Carlos Melgar, Jill M. Dunlop, and James P. Syvertsen
Donald L. Peterson, Ralph Scorza, Stephen S. Miller, and D. Michael Glenn
Six cultivars and three advanced breeding selections of fresh-market peaches (Prunus persica Batsch.) were evaluated for once-over mechanical harvesting. Factors evaluated were uniformity of maturity, fruit size, and incidence of damage in firm-ripe fruit. Harvest date was determined by estimating visually when equal amounts of green and over-ripe fruits were on the tree. In practice this criterion was difficult to achieve. Only on two occasions during the 2-year test did the proportion of firm-ripe fruit exceed 80% of total harvested fruit. Mean incidence of damage due to mechanical harvesting ranged between ≍2% and 12%. Nonuniformity of maturity of fruit on a given tree is a major hindrance to once-over harvesting of peaches.
Robert F. Kasmire
Quality in this discussion is interpreted as the market quality, and not nutritional quality, of products. Market quality is comprised of the inherent quality and maturity of a product at harvest, and the condition of the product after the harvesting operation. Mechanical harvesting (MH) includes handling steps from removing plants or plant parts from the field (soil or plant) to delivering them onto a field packing facility or field vehicles for subsequent transporting to packing houses or processing plants.
Kuo-Tan Li* and James P. Syvertsen
Mechanical harvesting of citrus trees by trunk or canopy shakers can cause leaf and twig removal, bark injury and root exposure. Such problems have restricted the adoption of mechanical harvesting in Florida citrus. We assessed physiological responses of citrus trees that were mechanically harvested with a linear-type trunk shaker, operating at 4 Hz, 70.8 kg mass weight, and 6.5 cm displacement, for 10 or 20 seconds. We measured fruit recovery efficiency, leaf and shoot removal, mid-day stem water potential, leaf gas exchange, and leaf fluorescence emission of mature `Hamlin' and `Valencia' orange trees under restricted or normal irrigation. Shaking treatments effectively removed 90% to 94% of fruit without bark damage. Compared to harvesting by hand, trunk shaking removed 10% more leaf area and twigs, and caused some visible exposure of fibrous roots at the soil surface. There were no significant treatment differences on mid-day stem water potential, leaf gas exchange, and leaf photosystem efficiency. Excessively shaken trees for 20-30 seconds can temporary induce stress symptoms resembling that in trees without irrigation. Trees may have benefited from the low levels of leaf and twig loss after trunk shaking that compensated for any root loss. Long-term effects of trunk shaking will be assessed by tree growth, return bloom, subsequent yield, and carbohydrate reserves.
Richard B. Smith
Mechanically harvested fruit of the strawberry (Fragaria × ananassa Duch.) cv. Veeglow destined for processing can be stored at 1°C in bulk bins for 4 to 6 days if room-cooled, and for 6 to 8 days if forced-air cooled promptly after harvest, without appreciable loss due to rot development or of quality of processed product. Yields of puree from fresh fruit mechanically harvested on day 8 of the storage trial were lower than for fruit that had been forced-air cooled and stored at 0° for 8 days. Sulfur dioxide fumigation immediately after cooling reduced losses due to rot and lowered mold counts, particularly when the fruit was room cooled.
G. C. Martin, S. Lavee, and G. S. Sibbett
(2-chloroethyl)phosphonic acid (ethephon) applied at pH 6.8 to 7.0 resulted in fruit loosening which allowed mechanical harvest of at least 85% of the olive crop but there was excessive leaf loss. Inclusion of calcium salts helps offset leaf loss, but also decreases fruit loosening. 2-chloroethyl-tris-(2-methoxyethoxy)-silane (Alsol) and (2-chloroethyl)-methyl-bis-(phenylmethoxy)-silane (CGA 15281) appeared to be more superior looseners than either ethephon or GAF 7767141 (an ethylene generating material) with less leaf loss following treatment.
L. A. G. van Heek and H. H. Adem
A low cost single sided harvester with a multi-level catching device was designed to harvest fruit from Tatura Trellis trees planted at 6 × 1 m. Limb Shakers were used to remove cling peaches (Prunus persica (L.) Batsch) and the machine-harvested fruit showed fewer injuries than fruit picked by contract labor. Although the machine harvested peaches had a greater proportion of cut fruit, the percentage of bruised fruit was significantly lower. Bruising was shown to be a function of flesh firmness for both harvesting methods. ‘Williams’ Bon Chretien’ (‘Bartlett’) pears (Pyrus communis L.) were harvested with a trunk shaker from single trellis type limbs in a standard orchard which had been modified for mechanical harvesting. Comparisons between the trellis harvester, a 2-unit Catchall harvester and fruit picked by contract labor showed that the proportion of bruised fruit was lowest for the trellis harvester. Relationships were established between the location of pears within the canopy of trellis type limbs and damage to fruit. Trunk shaking caused displacement of fruit and branches resulting in damage to fruit. Results show that trellis pear trees may be suitable for mechanical harvesting if fruit is used for processing.
Timothy M. Spann, Luis V. Pozo, Igor Kostenyuk, and Jacqueline K. Burns
only $0.0757 more per pound soluble solids than Florida growers. This discrepancy in production costs has been a major driving force in Florida's efforts to develop mechanical harvesting technology ( Florida Department of Citrus, 2010 ; Whitney, 1995
C. E. Arnold and A. E. Mitchell
Scald was the major grade lowering defect resulting from mechanical harvesting of sour cherries for processing. Histological sections of scalded tissue showed no crushing or distortion of cells, but the epidermal cells appeared dense and the cell walls appeared to be thicker than those of nonscalded tissue. Since the cells of scalded tissue did not appear distorted, bruising apparently induced a chemical change as a result of membrane disruption bringing about discoloration. Microscopic examination indicated that darkened bruises on the epidermis of the cherries occurred prior to mechanical harvesting. Tannins were located primarily in the epidermal region, but during a 24-hour soak there was a slight movement of tannin into the outer cortical cells. Greater movement occurred in mechanically harvested cherries than in handpicked fruit. The cellular disruption resulting from bruising by mechanical harvesting possibly aided the movement of tannins. Scald was a major grade lowering factor when mechanically harvested cherries were soaked longer than 8 hours before processing.
G. S. Howell Jr., B. G. Stergios, S. S. Stackhouse, H. C. Bittenbender, and C. L. Burton
Application of (2-chloroethyl)phosphonic acid (ethephon) reduced fruit removal force (FRF) as much as 50% depending on concentration and time of application. Reduction in FRF allowed reduced mechanical harvesting vibration frequency which reduced damage to berries during harvest and thus increased shelf-life. Mechanical harvest was further facilitated by ethephon-induced color development and hastening of abscission which reduced the number of machine harvests required.