Search Results
Abstract
(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.
Abstract
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.
Abstract
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.
Ethephon was applied at 0, 625, 1250, 1875, and 2500 m·gliter-1 in 2 consecutive years to `Arbequina' olive trees to determine its effect on fruit removal with mechanical harvesting and on fruit oil composition. Ethephon increased the mechanical harvesting efficiency by 20%. Ethephon at 1250 and 1875 mg·liter-1 were the optimum treatments, resulting in 63% and 66% of the olives being mechanically harvested, respectively, with a preharvest olive drop of 10% and 11%. Leaf drop (4.6 and 4.8 kg/tree fresh weight, respectively) at these concentrations did not reduce flowering the following year. Oil acidity, peroxide value, and fatty acid composition were affected little by ethephon and the values observed were within the range of normal annual variation. These results suggest that ethephon did not modify oil quality and that its use on traditionally pruned `Arbequina' trees is not economically justifiable. Chemical name used: (2-chloroethyl)phosphonic acid (ethephon).
Abstract
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.
Mechanical harvesting of citrus trees can cause physical injuries, such as shedding of leaves, exposing roots, and scuffing bark. Although mechanical harvesting usually has not reduced yield, physiological consequences to the tree from these visible injuries have not been investigated. We hypothesized that physical injuries to tree canopies and root systems from a properly operated trunk shaker would not cause short-term physiological effects. Tree water status and leaf gas exchange of mature `Hamlin' and `Valencia' sweet orange [Citrus sinensis (L.) Osb.] trees that were harvested by a trunk shaker were compared to hand-harvested trees. A trunk shaker was operated with adequate duration to remove >90% of mature fruit or with excessive shaking time under various environmental conditions and drought stress treatments throughout the harvest season. Mid-day stem (Ψstem) and leaf (Ψleaf) water potentials along with leaf gas exchange were measured before and after harvest. Trees harvested by the trunk shaker did not develop altered water status under most conditions. Trees harvested with excessive shaking time and/or with limited soil water supply developed low Ψstem resembling Ψstem of drought-stressed trees. However, water potential of all treatments recovered to values of the well-irrigated, hand-harvested trees after rainfall. In addition, mechanical harvesting did not reduce CO2 assimilation, transpiration, stomatal conductance, water use efficiency, or photosystem II efficiency as measured by chlorophyll fluorescence. Thus, despite visible injuries, a properly operated trunk shaker did not result in any measurable physiological stress.
Abstract
Cuts were generally more prevalent on mechanically harvested peaches than on those hand harvested, although they were usually within acceptable limits. Bruise development during storage was variable and often not significantly higher on machine harvested fruit than on those hand harvested. Fruit position within bulk bins appeared to influence subsequent bruise development. A prototype portable dumper-sorter did not significantly increase fruit injuries. Providing fruit were of comparable maturity, injuries to postbloom regulator-treated fruit were comparable to those untreated. The development of rots during storage was the greatest source of unmarketable fruit and is regarded as the most serious problem related to the mechanical harvesting of peaches for fresh market.
Abstract
Using a “shake and catch” method of mechanical harvesting with canes attached to a trellis, up to 70% of handpicked yield was collected from a clonal raspberry plantation in 1967 at Ottawa. Characters related to berry quality and to mechanical harvesting such as shape of receptacle, ease of picking, and fruit removal force were related to characters indicating susceptibility to winter damage. Thus, selection for winterhardiness is an important first step in further improving this material. Leaf retention in the fall was not a reliable indicator of winterhardiness. Efficiency was slightly reduced in 1970 with a method using untrellised plants and less dependence on winterhardiness. ‘Trent’ was the most suitable cultivar under both methods.
Abstract
Eight-year-old, semi-standard ‘McIntosh’ apple trees (Malus domestica Borkh.) were converted from central leader trees to open center trees by removal of the central leader. The productivity of the converted trees was not reduced in the first year due to better fruit set and size, and flowering and yield of the open center and central leader trees were similar in the second year. Open center trees resulted in less damage to the fruit during mechanical harvest, primarily due to reduction in fruit zone height.
Abstract
Bruising of apples is a major limitation for successful mechanical harvesting and that occurring within the tree probably determines the lower limit achievable. Bruising within the tree was studied by hand shaking 50-100 fruit samples onto a catching device which virtually eliminated bruising from this source.
Internal tree structure was modified by pruning entire trees and parts of trees from 8 to 14 ft. high to minimize the number of limb impact points by falling fruit. Bruising increased with tree height under all conditions of intervening branch structure. Pruning reduced bruising less than 10% on average trees. A minimum of 15-20% bruise results from the small branches on which fruit are borne independent of height. Limited branch density counts indicate that about 90% of the potential impact points of a large tree occur on branches less than one inch in diameter, where most of the fruit are borne.
These data indicate the limitations of pruning or branch padding to reduce internal tree bruising and suggest the use of smaller trees for the most economical reduction of bruise damage during mechanical harvesting.