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Richard P. Marini, James R. Schupp, Tara Auxt Baugher and Robert Crassweller

Canopies of ‘Gala’ and ‘Fuji’ trees, trained to the vertical axis, were divided into eight vertical sections, each representing 12.5% of the tree canopy. The diameter of all ‘Gala’ fruit and fruit weight for all ‘Fuji’ fruit were recorded for each canopy section. Fruit size from most canopy sections was normally distributed and distributions were similar for most sections. Therefore, fruit size distribution for a tree can be estimated by harvesting fruit from two sections of a tree, representing 25% of the canopy. For small trees in intensive plantings, with canopy diameters less than 2.0 m, average fruit diameter or fruit weight estimated from all fruit collected from 25% of the canopy may provide estimates within 7% of the true value.

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Richard P. Marini, James R. Schupp, Tara Auxt Baugher and Robert Crassweller

In three experiments, diameters of apples representing 7% to 30% of the fruit on a tree were measured at ≈60 days after full bloom. Using previously published regression equations, the early-season fruit diameter values were used to estimate apple fruit weight at harvest (FWH). At harvest, all fruit on sample trees were weighed and the distributions of estimated FWH for fruit measured early in the season were compared with distributions of the actual FWH for whole trees. Actual FWH was normally distributed for only one of the three experiments. Although the estimated mean FWH averaged for the 10 trees was within 9% of the actual mean FWH for all three experiments, the distribution of estimated FWH differed significantly from the actual distribution for all three experiments. All fruit were then assigned to appropriate commercial fruit sizes or box counts (number of fruit/19.05 kg). Fruit size tended to peak on the same four box counts for the estimated and actual populations, but the estimated populations had too few fruits in the small- and large-size box counts. Using early-season estimates of FWH, commercial apple growers and packers can predict fairly accurately the percentage of the crop that will fall into the peak box counts, but a more accurate early-season estimate of the fruit size distribution will likely require measuring 50% of the fruit on a tree.

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Richard P. Marini, James R. Schupp, Tara Auxt Baugher and Robert Crassweller

Early-season fruit diameter measurements for ‘Gala’, ‘Fuji’, and ‘Honeycrisp’ apples in three orchards for 3 years were used to develop regression models to estimate fruit weight at harvest. Fruit weight at harvest was linearly related to fruit diameter 60 days after bloom, but intercepts and slopes were not homogeneous for all nine combinations of orchards and years for any of the cultivars. When the entire data set for a cultivar was used to develop a single predictive model, the model was biased and underpredicted fruit weight for small fruit and overpredicted fruit weight for large fruit. Adding the ratio of (fruit weight/fruit diameter) at 60 days after bloom to the model with fruit diameter at 60 days after bloom produced a less-biased model with improved coefficients of determination, and predicted values were more similar to the observed values. The (fruit weight/fruit diameter) ratio was positively related to cumulative growing degree days for the 60 days before the fruit were measured and tended to be lower in years when fruits were exposed to frosts. These multiple regression models can be used to develop tables with predicted fruit weights at harvest for varying combinations of fruit diameter and (fruit weight/fruit diameter) ratio 60 days after bloom.

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Jianguo Li, Hong Zhu and Rongcai Yuan

. Hall, A. 2004 Inheritance of the Md-ACS1 gene and its relationship to fruit softening in apple ( Malus × domestica Borkh) Theor. Appl. Genet. 108 1526 1533 Osborne, D.J. 1989 Abscission Crit. Rev. Plant

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Larry E. Schrader, Jianguang Zhang, Jianshe Sun, Jizhong Xu, Don C. Elfving and Cindy Kahn

, Z. Nyéki, J. 2005b Schadwirkung des Sonnenbrands auf das Gewebe des Apfels ( Malus domestica Borkh.) (in German with English abstract) Gesunde Pflanzen 57 47 52 Racskó, J. Szabó, Z. Nyéki, J

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Keith Yoder, Rongcai Yuan, Leon Combs, Ross Byers, Jim McFerson and Tory Schmidt

Chemical thinning is one of the most effective measures to improve apple ( Malus domestica Borkh.) fruit size, color and quality at harvest, increase return bloom the next year, reduce biennial bearing, and increase the profitability of

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In the article titled “Ethephon as a Blossom and Fruitlet Thinner Affects Crop Load, Fruit Weight, Fruit Quality, and Return Bloom of ‘Summerred’ Apple (Malus ×domestica) Borkh.,” by Mekjell Meland and Clive Kaiser [HortScience 46(3):432-438; March

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Manjul Dutt, Daniel Stanton and Jude W. Grosser

factor enhances biosynthesis of anthocyanins, distinct proanthocyanidins and phenylpropanoids in apple ( Malus domestica Borkh.) Planta 226 5 1243 1254 Liang, Z. Wu, B. Fan, P. Yang, C. Duan, W. Zheng, X. Liu, C. Li, S. 2008 Anthocyanin composition and

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Mehdi Sharifi, Julia Reekie, Andrew Hammermeister, Mohammed Zahidul Alam and Taylor MacKey

performance in an organic apple ( Malus domestica Borkh) orchard in northern Patagonia Plant Soil 292 193 203 Schmid, A. Weibel, F. 2000 Das Sandwich-System–ein Verfahren zur herbizidfreien Baumstreifenbewirtschaftung? [The Sandwich System, a procedure for

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Gregory M. Peck, Ian A. Merwin, Christopher B. Watkins, Kathryn W. Chapman and Olga I. Padilla-Zakour

The northeastern United States has a humid climate where frequent summer precipitation creates high disease pressure and intense weed competition as well as a long history of apple ( Malus × domestica Borkh.) cultivation that has allowed for the