Yield, fruit size, red color, and estimated crop value in the NC-40 1990 cultivar/rootstock trial in Virginia

An NC-140 apple cultivar/rootstock trial was conducted near Blacksburg, VA from 1990 through 1999. In addition to the four cultivars common to all sites ('Golden Delicious', 'Jonagold', 'Empire', and 'Rome'), we also had 'Stayman', and 'York'. Rootstocks were Mark, Ottawa 3 (O.3), Budagovsky 9 (B.9), Malling 9 EMLA (M.9EMLA), and Mailing 26 EMLA (M.26EMLA). Our objective in this supplemental study was to evaluate cultivar and rootstock effects on yield, distribution of fruit sizes, and color in order to estimate value of the crop. After eight years of cropping, there were very few significant cultivar x rootstock interactions; therefore, mostly main effects are presented. Fruit size was largest for 'Rome' and 'Jonagold', intermediate for 'Stayman' and 'York', and smallest for 'Golden Delicious' and 'Empire'. Trees on M.26EMLA and M.9EMLA produced somewhat larger fruit than did trees on Mark and O.3. Fruit from trees on B.9 were intermediate in size. Red color was variable, so in spite of significant differences, general conclusions were impossible. Projected value/tree for fresh fruit ('Empire', 'Rome', and 'Stayman') based on yield, fruit size, and red color was greatest for trees on M.26EMLA and M.9EMLA, intermediate for trees on O.3, and lowest for trees on Mark and B.9. In estimated value for processing,'York' was higher than 'Golden Delicious', and fruit from trees on M26EMLA, O.3, and M.9EMLA were higher in value than those from trees on Mark and B.9. As apple rootstocks have been evaluated in NC-140 trials, prime attention has been paid to survival, tree size, precocity, yield, and mean fruit size (1, 10, 11). In some cases, there have been data published on fruit quality attributes such as soluble solids levels, starch indices, and maturity ratings (2, 3, 4). However, because of limited time and resources, most of the fruit size data have been based on mean fruit weight determined from a 50-fruit sub-sample per tree (10,11). Unfortunately, mean fruit weight provides no information on either the range or distribution of fruit sizes. Therefore, economic projections of the relative value of the crop from the test trees is impossible. As a supplement to the 1990 NC-140 Apple Cultivar/Rootstock Trial, we sized all fruit for six of the eight years in which fruit were harvested. In addition, a sub-sample of fruits was evaluated for red color. From a combination of yield data within these two data sets, we estimated crop values.