Abstract
‘Linn’, ‘Olympus’, and ‘Totem’ strawberry (Fragaria × ananassa Duch.) were defoliated on various dates in 1979 during mechanical harvest or by leaf mowing after hand harvest, and numbers of crown divisions, runners, and inflorescences as well as berry size, fruit rot, and yield were measured in 1980. The only difference attributable to defoliation dates was berry size in ‘Olympus’ and ‘Totem’. Defoliation by mechanical harvest did not adversely affect subsequent plant growth and yield.
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
The purpose of this study was to determine if over-the-row mechanical shake-catch harvesting affected root development, leaf water stress, and yield of young ‘Golden Delicious’/M.7A and ‘Law Rome’/MM.111 apple (Malus domestica Borkh.) trees. Leaf water potential and temperature differential (canopy-air temperatures) were not significantly altered by mechanical harvesting. A minirhizotron technique did not detect changes in root distribution or root morphology. The fruit yield was unaffected by mechanical harvesting for four harvest years. No deleterious effects were detected as a result of over-the-row shake-catch harvesting.
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.
An experiment was conducted to evaluate the mechanical harvesting and processing suitability of four standard strawberry [Fragaria ×ananassa (Duch.)] cultivars (`Kent', `Glooscap', `Bounty', and `Midway') and the recent introductions `Chambly' and `Oka'. `Kent', `Glooscap', `Oka', and `Chambly' had the highest yields and heaviest fruit. Similar percentages of berries of all cultivars were destroyed by the harvester. `Oka' and `Midway' were not suitable for this type of mechanical harvesting due to their susceptibility to bruising during harvest. Based on total marketable fruit harvested mechanically, `Chambly' was the most and `Oka' was the least adapted cultivars for this particular harvester. `Chambly' and `Glooscap' were easiest to decap, followed by `Bounty', `Oka', and `Midway'. None of the cultivars tested were suited ideally for machine harvesting, and further breeding is required to produce well-adapted cultivars.
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
In the mechanical harvesting of sour cherries suitable attention has been given to the rate of harvest (1,2,8), the relative cost (8) and to varying mechanical (4,5,6,8) and to cultural (2,3,7) aspects related to the physical condition of the harvested fruit. Another factor in the mechanical harvesting efficiency which is of considerable importance to the grower is the percentage of the crop borne by the tree that is removed in the harvesting process. Claypool (3) has indicated that for many species of fruit, current mechanical harvesting techniques may remove fruit within 5% of that achieved by hand-picking. Cain (1) has shown variations from 70 to 96% of crop removal for sour cherries depending on the stage of maturity and the level of nitrogen fertility. The latter figure is comparable to average hand-picking. Since the fruit left on the tree after shaking are a total loss (8) and represent a proportionate share of the total cost of production up to harvest time, the achievement of maximum crop removal is of importance in any harvesting operation.
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
Mechanical harvesting has, of course, long been standard for many annual crops, the “combine harvester” for wheat being an early, and successful, example. In some instances (e.g., tomato, plant breeders have “tailor made” cultivars to adapt them to mechanical harvesting. Typically, such annuals are destroyed in harvesting. The plant must be preserved with perennial crops, although sometimes considerable injury to the plant can be acceptable when (as for grapes or raspberries) the plant is severely pruned annually. Substantial damage to the plant (tree) is not acceptable, in mechanical harvesting of tree crops, but leaf damage is of minor consequence for deciduous tree crops, and the fruit is biologically destined to abscise; if it is not harvested. Damage to the product is not a problem, it will soon fall naturally for some deciduous tree crops (particularly nuts of various kinds). In contrast, mechanical harvesting of citrus fruits involves quite extraordinary problems. The tree is evergreen and substantial leaf damage is not acceptable. The fruit has no clearly defined abscission period. The same grapefruit that might be picked in October can hang on the tree until May. Citrus fruits are extremely subject to decay. ‘Valencia’ (an important cannery orange cultivar) takes 12 to 18 months from bloom to acceptable maturity to complicate matters further. Thus, there are 2 crops on the tree at harvest time; mature fruit that are to be harvested and immature fruit that must not be damaged or removed. It is apparent after 20 years and millions of dollars spent in Florida that the problem (particularly for ‘Valencia’) is as much biological as it is mechanical. The fruit, but not the leaves, must be made to abscise and, for ‘Valencia’, the tree must retain the immature crop while releasing the mature fruit.
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.