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Kuo-Tan Li, Jim Syvertsen, and Jacqueline Burns

The shedding of leaves, branches, flowers, and young fruit; scuffing of bark; and exposed roots that are caused by trunk or canopy shakers during harvest appears to be unavoidable, but generally does not reduce long-term yields. Nonetheless, such visible injuries have limited the widespread adoption of mechanical harvesting in Florida's citrus industry. We determined if such physical injuries caused by a properly operated trunk shaker resulted in any physiological injures or any consequent decline in vigor and productivity of well-managed, healthy citrus trees. We continuously monitored various physiological indexes in mature `Hamlin' and `Valencia' orange trees annually harvested by hand or by a linear-type trunk shaker with various shaking durations. Trunk shaking did not reduce return bloom, fruit set, young fruit growth, or canopy and root growth. There was a correlation between the seasonal timing of a simulated bark injury and recovery from the injury. Although some root exposure was frequently observed during trunk shaking, leaf water relations and fine root growth were unaffected. There was no difference in leaf dry weight per area and leaf nitrogen among treatments. Mechanical and hand harvesting in late season `Valencia' during full bloom removed similar amounts of flowers. However, immature fruit were removed by trunk shaking when `Valencia' were harvested after mid-May, and the number of young fruit removal increased with shaking duration and fruit size. The loss of young fruit for the next crop remains a major problem of mechanical harvesting in late harvest `Valencia'.

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Muhammad Farooq, Masoud Salyani, and Jodie D. Whitney

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.

Open access

F. J. Sundstrom, C. H. Thomas, R. L. Edwards, and G. R. Baskin

Abstract

Nitrogen rate and in-row plant spacing significantly influenced yields of mechanically harvested red Tabasco (Capsicum frutescens L.) pepper. Red pepper yields increased with an increase in N rate from 0 to 112 kg N/ha, and a decrease in in-row plant spacing from 81 to 10 cm. The percentage of machine harvested red pepper in relation to green and orange fruit removal was enhanced with 20 cm in-row spaced plants. Tabasco plant height increased with an increase in N rate from 0 to 112 kg N/ha, while plant diameter decreased with a decrease in in-row spacing from 81 to 10 cm. Conventionally spaced (81 cm in-row spacing) Tabasco plants were damaged substantially more during mechanical harvesting than 10 cm in-row spaced plants. Early season leaf-petiole tissue N concentrations had higher correlations with red pepper yields than did late season tissue N concentrations. Multiple harvests of red Tabasco pepper with a flail-type machine produced yields similar to those obtained with hand harvesting.

Open access

John C. Cain

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.

Free access

Terence L. Robinson, William F. Millier, James A. Throop, Stephen G. Carpenter, and Alan N. Lakso

Mature `Empire' and `Redchief Delicious' apple trees (Malus domestica Borkh.) trained to a Y-shaped trellis (Y/M.26) or trained as pyramid-shaped central leaders (CL/M.7) were mechanically harvested with the Cornell trunk recoil-impact shaker during 4 years. With `Empire', fruit removal from the Y/M.26 trees (85% to 90%) was significantly less than from the CL/M.7 trees (95% to 97%). With `Delicious' there were no differences in fruit removal (90% to 95%) between the two tree forms in any year. When the catching pad was on the ground, fruit grade based on damage was only slightly better for the Y/M.26 trees than for the CL/M.7 trees. When the catching pad was raised up near the Y/M.26 canopy, fruit grade was significantly improved for the Y/M.26 trees and was better than the CL/M.7 trees. Fruit grade for both cultivars ranged from 83% to 94% Extra Fancy with 5% to 16% culls for the Y/M.26 trees and from 74% to 88% Extra Fancy and 11% to 21% culls for the CL/M.7 trees. Skin punctures, skin breaks, and number of large and small bruises were lower and the percentage of nondamaged fruit was higher with the Y/M.26 trees when the pads were close to the canopy than when the pads were on the ground. The CL/M.7 trees had higher levels of all types of fruit damage than did the Y/M.26 trees. Damaged fruit from the CL/M.7 trees was mainly from the top half of the tree, while fruit from lower-tier scaffold branches had low levels of damage. Mechanically harvested fruit from the Y/M.26 trees had lower incidences of fruit rot and flesh breakdown after a 6-month storage period than did fruit from the CL/M.7 trees. Stem pulling was high with both systems and averaged 60% for `Delicious' and 30% for `Empire'. The advantage of the single plane Y-trellis system for mechanical harvesting appears to be that the catching pads can be placed close to the fruit, thereby reducing fruit damage.

Open access

Stephanie J. Walker, Paul Funk, Israel Joukhadar, Tom Place, Charles Havlik, and Bradley Tonnessen

The New Mexico State University (NMSU) Agricultural Experiment Station announces the release of ‘NuMex Odyssey’, a New Mexican–type chile pepper ( Capsicum annuum ) cultivar that is efficient for mechanical harvest of green fruit. This cultivar is

Open access

J. N. Moore, G. R. Brown, and H. L. Bowden

Abstract

Weekly yields of hand-harvested strawberries (Fragaria × ananassa Duch.) were compared with weekly percent ripening concentration and total seasonal yields for 45 to 57 clones during 6 seasons at 2 locations in order to identify the production characteristics useful in selecting genotypes suitable for once-over mechanical harvest High weekly yields were positively correlated with high total seasonal yields in every yearly and location comparison. In contrast, high weekly yields were positively correlated with high weekly percent ripening concentration in only 1 of 9 comparisons. Thus, selection of clones with high total seasonal yields is an efficient method of developing high “once-over” yielding cultivars. High seasonal yields and high weekly percent ripening concentration are independent traits, and the combination of these factors will result in cultivars capable of producing very high single harvest yields.

Open access

Peter J. Stoffella and Mark Sherman

Abstract

Three jointless tomato (Lycopersicon esculentum Mill.) cultivars, ‘MH-1’, ‘Hayslip’, and ‘Burgis’, were evaluated for fruit yields using a semi-mechanical freshmarket tomato harvester. Harvest dates were 85 or 99 days after transplanting in Fall 1980, and 88 or 95 days after transplanting in Fall 1982. Total fruit yields of the late harvest were significantly higher than the early harvest in 1982, but not in 1980. An increased percentage yield (weight basis) of colored fruit occurred during the late harvest in both trials. ‘Burgis’ and ‘Hayslip’ had significantly higher green fruit yields and lower ripe fruit yields than ‘MH-1’ in both years. Yields of semi-mechanically harvested fruit were reduced by an average of 25% and 47% when compared with manually harvested fruit yields during 1980 and 1982, respectively.

Open access

Paul E. Read and D. J. Fieldhouse

Abstract

Yields of tomato cultivars ‘Heinz 1350’ and ‘Delaware 65S3-2’ (a mid-season processing variety) were increased by foliar sprays of succinic acid 2,2-dimethyl hydrazide (Alar) and 2-chloroethyl trimethylammonium chloride (Cycocel). The most effective treatments were those in which 2500 ppm Alar was applied at the first or fourth true leaf stage of growth or at both of these times. Concentration of harvest was improved and early yield was increased by subsequent application of 5000 ppm Alar as a flower “cut-off” spray after desired fruit set had been achieved. The latter treatment has desirable implications for mechanical harvesting, since it virtually eliminated green fruit “pick-out” and slowed vegetative growth, thus causing a more concentrated harvest because of more rapid fruit maturation.

The yield increases are attributed to a combination of effects including resistance to water and heat stresses, more flowers per cluster and thus more fruits per plant. Additional hormone-like effects of Alar and certain Alar analogs were observed.

Open access

Avinoam Golomb, Shimshon Ben-Yehoshua, and Yoav Sarig

Abstract

Superficial scratches were a major problem in mechanically harvested ‘Marsh Seedless’ grapefruit (Citrus paradisi Macf.). Sealing individual fruit in 0.015 mm thick high-density polyethylene (HDPE) sheets greatly reduced fruit weight loss under uncontrolled room conditions. HDPE-wrapped fruit retained excellent external and internal qualities for 3 months, but was slightly softer and began to develop an unfresh off-flavor and external yellow-orange color during the 4th month of storage. HDPE wrap did not keep the injury scars invisible but improved active healing and inhibited further softening and spreading of scars, thus partly preserving fruit appearance. Highest phenylalanine ammonia-lyase (PAL) enzyme activity, a key process in lignification and wound healing, occurred in scratched, HDPE-wrapped fruit stored at 30°C. Peak activity was reached 72 hours following injury. Decay of scratched fruit by Penicillium digitatum Sacc. was reduced markedly by storage at low temperature (10°), by disinfection, or by wrapping in HDPE. The beneficial anti-decay effects of HDPE can be attributed both to insulation against secondary contact infections and to provision of a humid atmosphere which at warm temperature enhances lignification and the healing process of superficial flavedo scars.