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  • Author or Editor: C. E. Gambrell Jr. x
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Abstract

Several peach varieties were sprayed with 3-chlorophenoxy-α-propionamide (3-CPA) at different stages of fruit development. The timing of the application was critical, and varieties differed greatly in their thinning response. The ‘Ranger’ variety was thinned with ease, but attempts to thin ‘Cardinal’ with 3-CPA were unsuccessful. Fruit thinning apparently increased the cold hardiness of the flowers during the following bloom period. Several spray additives were found to increase the thinning effectiveness of 3-CPA.

Open Access

Abstract

Bloom or postbloom sprays of 2-chloroethylphosphonic acid (Ethrel) thinned peaches. Applications at full bloom did not produce consistent thinning in ‘Cardinal’. Postbloom sprays applied approximately at endosperm cytokinesis produced consistent thinning of 3 cultivars.

Degree of thinning was related to time of Ethrel application. Most thinning was obtained when Ethrel was applied near the end of Stage I or during Stage II. Ethrel sprays within a month after full bloom caused significant fruit size reduction that persisted 2 months or more after treatment. Ethrel sprays within 50 days of harvest accelerated maturity of several cultivars.

Open Access

Abstract

A single-value estimate of maturity response and an independent estimate of the thinning response to treatment can be determined from detailed harvest records. Thinning index is estimated from the total number of fruit per tree; maturity response is estimated from the weighted-average harvest date.

Open Access

Abstract

Postbloom application of gibberellin A3 (GA3) to open pollinated peach trees prevented seed development in some fruit, and also resulted in the persistence and maturation of both seeded and seedless fruit on the same trees. GA3 temporarily promoted fruit growth and delayed abscission of both seeded and seedless fruit, but the final crop load was not altered. Both seeded and seedless fruit abscised from treated trees during physiological drop. The persisting seedless fruit, therefore, competed successfully with seeded fruit. Seedlessness was associated with smaller fruit size at maturity.

Open Access

Abstract

A 500 ppm gibberellin A3 (GA) spray applied shortly after full bloom to unemasculated peach flowers caused some fruit to develop parthenocarpically. Nonparthenocarpic fruit sprayed with GA were similar to parthenocarpic fruit in their elongated shape and advanced maturity, and dissimilar to unsprayed control fruit. The applied GA, rather than a lack of ovule development, is therefore primarily responsible for alterations in shape and maturity of parthenocarpic peaches.

Open Access

Abstract

Ethephon ((2-chloroethyl)phosphonic acid) at 50 to 200 ppm hastened the maturation of peach fruit of the cvs. ‘Cardinal’, ‘Ranger’, ‘Redhaven’, ‘Blake’, and ‘Richhaven’ over a range of application times. Stimulation of maturation was not attributed solely to reduced fruit load, since an influence on maturation was found even when ethephon-treated trees bore no fewer fruits than hand-thinned controls. When treated and nontreated ‘Richhaven’ fruit were harvested at a comparable maturity based on firmness, ground and flesh color a and a/b values were increased by ethephon, as were soluble solids. No differences were found in b values for ground or flesh color or in total titratable acidity. Fruit treated with ethephon exhibited more uniformity in firmness and color than untreated fruit at shipping maturity, a characteristic which has potential value in facilitating once-over mechanical harvesting operations.

Open Access

Abstract

Succinic acid -2,2-dimethylhydrazide (Alar) was applied at various postbloom spray intervals and concentrations to ‘Ranger’ peaches from 1965 to 1969 and to ‘Cardinal’ and ‘Blake’ peaces in 1969. Fruit of each cultivar was harvested at a uniform firmness to determine the influence of Alar on quality attributes not directly associated with changes in fruit maturity. Color attributes, particularly flesh color, were enhanced by Alar over a wide range of spray dates to a much greater degree than other quality attributes at a given maturity. The results indicated a stimulation of anthocyanin biosynthesis by Alar without a corresponding effect on other attributes normally considered to be indicators of physiological maturity.

Open Access

Abstract

Peach samples were taken by removing all fruit from preselected limbs at 1 date for each treatment just prior to the 1st commercial harvest, Maturity was evaluated by the indices of firmness, size, undercolor, and overcolor. The estimates of variance among fruit for the maturity attributes were used to objectively measure fruit uniformity. These estimates of variance were then subjected to the analysis of variance to test for differences of fruit uniformity among growth regulator treatments.

Open Access

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.

Open Access

Abstract

The ethylene-releasing agent CGA-15281 (2-chlorethyl-methylbis (phenylmethoxy) silane) effectively thinned fruit of several cultivars of peach [Prunus persica (L.) Batsch.]. Thinning varied with cultivar, stage of development, concentration, and application technique. Negligible (<1%) leaf injury and drop occurred even at the higher (720 ppm) concentration over the 8-year period.

Open Access