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  • Author or Editor: Donald L. Peterson x
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Abstract

Tree fruit production is a labor intensive operation requiring an average of over 300 manhours/ha (38), which represents the largest single production cost (15). Most of this labor is seasonal, with hand pruning and harvesting accounting for 30% and 50%, respectively, of the total cost (6, 17, 34). The supply of skilled domestic workers to perform necessary operations usually does not meet the seasonal labor requirement. Substantial numbers of undocumented aliens are employed to reduce this shortage; but they represent an unstable supply (29, 33). Increased mechanization is one option for alleviating this labor shortage. Increased importation of low priced foreign fruit and fruit products is another justification for increased mechanization to reduce costs and keep American orchardists competitive (33).

Open Access

Hand-harvesting fruit crops is labor-intensive, and the supply of dependable, skilled labor is a concern of the fruit industry. Only a small portion of all fruit crops is harvested mechanically, primarily for processing. Public funding of mechanical harvesting research on fruit crops has reached a low level. However, there is renewed interest in mechanical harvesting research due to the potential scarcity of hand-harvest labor and new federal laws that may deplete further the labor pool. Much of the research expertise in mechanical harvesting of fruit crops has been lost, since most projects have been discontinued. Considerable lead time will be required to develop facilities, personnel, and projects if the decision is made to initiate publicly funded harvest mechanization research. More time will be required before commercially acceptable techniques and methods will be available. A majority of the research described in this paper was conducted outside the United States. The United States will not remain competitive in the world market for fruit crops with the present lack of mechanical harvesting research.

Free access

Abstract

Separation pull force of thornless blackberries (Rubus spp.) decreased at a rate insufficient to allow adequate mechanical harvest differentiation between the black ripe and red fruit. When a force sufficient to remove 80% of black ripe fruit was applied to floricanes, green and red fruit comprised as much as 50% of detached fruit. Ethephon, applied at 500 and 1000 ppm 4 days prior to harvest, reduced fruit size and total soluble solids, but increased the ripe/unripe harvest ratio more than two-fold. Two shaker models tested were effective in removing black ripe fruit. Of the two, the unit with higher frequency (40 vs. 25 Hz), but with shorter stroke (1.7 vs. 5.0 cm), was more efficient, as it removed fewer unripe fruit. Chemical name used: (2-chloroethyl) phosphonic acid (ethephon).

Open Access

There is increased interest in growing blackberries in the United States for the fresh fruit market. For fresh market blackberry production, >350 h/acre (900 h·ha-1) of work is required to hand pick blackberries over a season that lasts 5 weeks with harvest every 2 days. Existing bramble mechanical harvesters can detach fruit from plants trained on a vertically oriented I trellis and harvest more cheaply than when harvested by hand, but the harvested fruit does not have fresh-market quality. We developed a cane training and trellis system for semierect blackberries to orient canes horizontally with the fruit positioned below the canes. Also, we developed an over-the-row mechanical harvester that uses vibrating nylon rods on a drum to shake fruit from horizontally trained canes onto a moving fruit-catching surface directly under the canopy to minimize impact damage to fruit. A new trellis design, new cane training practices, and new harvesting technologies have allowed fruit to be removed efficiently and be acceptable for fresh-market sales. This production system has been evaluated economically and appears to be profitable. It could overcome the high cost of handpicking, which has limited the expansion of fresh-market blackberries.

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Abstract

Depending on soil-surface conditions, an electronic pick-up and counting device to signal within-row tree distances using a mechanical tree planter produced planting distances as accurate or more accurate than those obtained with traditional planting techniques.

Open Access

A study was conducted to characterize vegetative growth of mature 'Chester Thornless' blackberry plants trained to the rotatable cross-arm (RCA) trellis in which up to six primocanes were retained. Cane emergence occurred from mid-April to late-May. The first (oldest) primocane attained a sufficient height to be trained in early May in 40% of plants, but younger primocanes could not be trained until late July. However, only 94%, 73%, 60%, and 42% of plants developed three, four, five, and six primocanes, respectively. In primocanes that were trained from 14 May to 3 June, eight or nine medium (0.7-1.3 m) to long (>1.3 m) lateral branches developed. Primocanes tied from 4 June to 16 July averaged less than six lateral branches that were mostly of medium and short (<0.7 m) categories. Primocanes trained after 16 July produced only two short lateral branches. The results indicated that training primocanes from mid-May to mid-June for 'Chester Thornless' blackberry on the RCA trellis would be advantageous to minimize labor costs.

Free access

Mature 'Chester Thornless' blackberry plants were trained to the rotatable cross-arm (RCA) trellis to determine the effect of retaining two, four, or six primocanes on plant productivity. Retention of only the two oldest primocanes and generally the most vigorous primocanes per plant yielded 14.1 kg of fruit compared to 17.1 kg per plant in which as many as six primocanes were retained. Increasing the number of canes did not result in significant yield increase (P = 0.09) because the primocanes trained in late-June and July produced only a few, and, in some cases, no lateral branches. Thus, retaining only those canes that become trainable early in the season decreased labor inputs and allowed primocane training to be completed prior to the onset of harvest. As a result, the effort to train and retain only those primocanes that reach the trainable height before mid-June may be advantageous to minimize labor costs, but will not effect plant productivity.

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Hand-thinning (Prunus persica L. Batsch) “Y”-trained peach trees at bloom and 51 days after full bloom (DAFB) was compared to mechanical fruit thinning 51 DAFB using a spiked-drum and an impact shaker. The spiked-drum shaker removed more fruit from horizontal branches than from vertical branches, yet did not selectively remove either large or small fruit. Bloom thinning by hand increased fruit size compared to postbloom thinning 51 DAFB, and both postbloom mechanical thinning techniques were as effective as postbloom hand thinning. The spiked-drum shaker may be a better thinning technique than the impact shaker because it transfers less shaking energy to the fruit, can be used in high-density plantings, and does not contact the trunk, lessening the potential for tree damage.

Free access

The purpose of this six year study was to re-evaluate the potential of mechanical peach harvesting in a mechanized irrigated peach production system. `Redhaven', `Harvester' and `Autumnglo' peach cultivars were trained to a free-standing “Y” form and received: a) full season irrigation; b) irrigation during the ripening period; or c) no irrigation. Trees were 2.5 m within the row and individual plots contained 10 trees with 4 replications in a split plot design. All three cultivars were mechanically harvested using the USDA inertial shaker. In addition, the cultivar `Autumnglo' was hand harvested as a control. The percentage of mechanically harvested firm ripe fruit ranged from 64 to 95%. Fruit damage ranged from 5 to 36%. In all years, non-irrigated trees tended to have the highest harvest percentage suggesting that irrigation may widen the maturity range of peach. Fruit damage occurred due to roughly cut shoot stubs and when debris in the canopy became lodged in the harvester's conveyor system. Accelerated tree death from mechanical harvesting was noted in `Autumnglo'. We concluded that the limitations to mechanical peach harvesting outlined in the 1970's have not been overcome.

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The purpose of these studies was to compare two mechanical means of thinning with hand thinning peaches 40-60 days after full bloom. A spiked-drum canopy shaker and a trunk impacter shaker were used to thin `Loring' peach trained to `Y' shape. Initial studies demonstrated that the spiked-drum shaker removed more fruit from horizontal than vertical branches. The spiked-drum shaker did not preferentially remove larger or smaller fruit. The yield of large fruit was not significantly different for hand or mechanically thinned trees when fruit was thinned 40-60 days after full bloom.

Free access