Location affects performance of 'Golden Delicious', 'Jonagold', 'Empire', and 'Rome Beauty' apple trees on five rootstocks over ten years in the 1990 NC-140 cultivar/rootstock trial

At 12 sites in the United States, trials were established in 1990 which included four apple (Malus X domestica Borkh.) cultivars ('Smoothee Golden Delicious', 'Nicobel Jonagold', 'Empire', and 'Law Rome Beauty') in all combinations on five rootstocks (M.9 EMLA, B.9, Mark, O.3, and M.26 EMLA). After ten growing seasons, rootstock and cultivar interacted significantly with location to affect trunk cross-sectional area (TCA), tree height, canopy spread, yield per tree, yield efficiency, and fruit size. Further, at many locations rootstock interacted significantly with cultivar to affect these parameters. In most cases, however, these interactions contributed minimally to the variability among rootstocks or among cultivars as they affected performance. Survival varied greatly by location, ranging from 43% in Kentucky to 100% in Massachusetts, Pennsylvania, and Virginia. Where tree loss occurred, more 'Rome' trees died than the other cultivars, and more trees on O.3 died than trees on the other rootstocks. Tree size also was affected by location, with TCA ranging from 48 cm² on average in Massachusetts to 131 cm² in Kansas. In general, largest trees were on M.26 EMLA, and the smallest were on Mark or on B.9. 'Jonagold' trees were consistently among the largest, and 'Empire' trees were among the smallest. Cumulative yield per tree (1992-99) ranged from 1.49 in Utah to 4.17 in Ohio, and the most yield efficient trees were those on B.9 and those on Mark. 'Jonagold' trees were consistently among the most yield efficient. Average fruit size (1992-99) ranged from 141 g in Tennessee to 224 g in Massachusetts. M.26 EMLA and M.9 EMLA generally resulted in the largest fruit, and Mark and O.3 resulted in the smallest. 'Rome' and 'Jonagold' fruit were consistently among the largest, and 'Empire' fruit were among the smallest.