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  • Author or Editor: T. A. Baugher x
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The objective of this study was to determine the relationship between temperature and color development in 3 strains of Red Delicious apple (Malus domestica Borkh). The strains `Scarlett Spur', `Ultrastripe' and `Starkrimson' were chosen based on variation in coloration. Chromaticity values (L* a* b*) were measured with a Minolta CR-200b calorimeter on 5 tagged apples on each of 4 trees of each strain. Measurements were made at approximately the same location on each fruit 23 times from July 11 through September 25, 1989. Differences in a*/b* ratio among strains were observed as early as the first sampling date; with `Scarlet Spur' having the highest ratio and `Starkrimson' the lowest. These differences were maintained for most the growing season. Temperature below 21C tended to enhance color development, whereas temperature above 21C reduced coloration. Temperature affected all 3 strains similarly.

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The objective of this study was to determine the relationship between temperature and color development in 3 strains of Red Delicious apple (Malus domestica Borkh). The strains `Scarlett Spur', `Ultrastripe' and `Starkrimson' were chosen based on variation in coloration. Chromaticity values (L* a* b*) were measured with a Minolta CR-200b calorimeter on 5 tagged apples on each of 4 trees of each strain. Measurements were made at approximately the same location on each fruit 23 times from July 11 through September 25, 1989. Differences in a*/b* ratio among strains were observed as early as the first sampling date; with `Scarlet Spur' having the highest ratio and `Starkrimson' the lowest. These differences were maintained for most the growing season. Temperature below 21C tended to enhance color development, whereas temperature above 21C reduced coloration. Temperature affected all 3 strains similarly.

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Abstract

A sampling plan was developed and used along with a modified grading scheme as a tool to predict apple (Malus domestica, Borkh.) fruit quality, thus providing a means to evaluate the impact of orchard management practices on market potential. Apple extra fancy/fancy packout was predicted to within 10% by examining a 100-fruit sample from each of five bins at the submersion tank. Packout loss factors were predicted to within 5% by sampling 100 fruit from each of four bins. A modified Russo/Rajotte grading scheme in chart format proved to be a useful tool for assessing packout losses. An evaluation of downgraded fruit, comparing the grading scheme to grower practice, yielded coefficients of determination ranging from 0.83 to 0.94 for five of six fruit lots sampled. The grower’s marketing intentions and the tendency of packinghouse staff to give more attention to the most obvious defects during grading influenced the ability to predict packout and the severity of loss factors.

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Apple packout audits were conducted during 1991 to 1993 to assess effects of five orchard systems (three cultivars, two age groups) on fruit packout and determine if relationships exist between light quality and productivity. Cultivar/rootstock combinations on 1979 T-trellis and central-leader systems had the lowest light levels and relative yields. Trees on either 1979 3-wire trellis, 1986 MIA, or 1985 West Virginia spindle had the highest light transmission, and trees on 1979 or 1985 West Virginia spindle systems had the highest yields. Extra fancy/fancy packouts across systems ranged from 40% to 85%. `Empire', regardless of system, had the highest packouts, and `Golden Delicious' on 1979 or 1986 central leader had the lowest packouts. A regression analysis comparing percentage packout in grades below fancy to percentage full sun indicated that reduced packouts were related to low light conditions. Orchard system influenced the number of fruit downgraded due to color, russet, bruises, bitter pit, cork spot, apple scab, rots, sooty blotch/fly speck, and tufted apple budmoth. Regression analyses comparing defects to field data indicated that bitter pit decreased as yield efficiency increased, and rot and sooty blotch/fly speck incidence were related to low canopy light penetration. Revenue losses were disproportionate to percentage of downgraded fruit because some defects had a greater impact on grade than others. The greatest revenue losses were for russet in `Golden Delicious' on 1986 central leader ($1656.60/acre) and for bitter pit in `Golden Delicious' on 1979 T-trellis ($1067.30/acre). Total losses in returns for individual systems ranged from $453.71/acre for `Empire' on 3-wire trellis to $3145.49/acre for `Golden Delicious' on 1986 central leader. The comparisons of young versus mature system yields and packouts indicate that medium- to high-density vertical or inclined canopy systems are superior to horizontal or low-density vertical freestanding systems. The cost-benefit analyses prescribe areas where management can be changed in existing systems to increase profitability.

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Hand thinning is a necessary and costly management practice in peach (Prunus persica) production. Stone fruit producers are finding it increasingly difficult to find a workforce to manually thin fruit crops, and the cost of farm labor is increasing. A new “hybrid” string thinner prototype designed to adjust crop load in vase or angled tree canopies was evaluated in processing and fresh fruit plantings in varying production systems in four U.S. growing regions in 2009. Data were uniformly collected across regions to determine blossom removal rate, fruit set, labor required for follow-up green fruit hand thinning, fruit size distribution at harvest, yield, and economic impact. String thinner trials with the variable tree forms demonstrated reduced labor costs compared with hand-thinned controls and increased crop value due to a larger distribution of fruit in marketable and higher market value sizes. Blossom removal ranged from 17% to 56%, hand thinning requirement was reduced by 19% to 100%, and fruit yield and size distribution improved in at least one string-thinning treatment per experiment. Net economic impact at optimum tractor and spindle speeds was $462 to $1490 and $264 to $934 per acre for processing and fresh market peaches, respectively. Case study interviews of growers who thinned a total of 154 acres indicated that commercial adoption of string-thinning technology would likely have positive impacts on the work place environment.

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