Performance of ‘Modi®’ Apple Trees on Several Geneva Rootstocks Managed Organically: Five-Year Results From the 2015 NC-140 Organic Apple Rootstock Trial

Abstract

In 2015, an orchard trial of ten apple rootstocks was established at ten locations in the United States and Canada using ‘Modi®’ as the scion cultivar. Trees were managed in accordance with United States organic standards to expose these rootstocks to the nutrient conditions and biome typically associated with organic tree-fruit production. Rootstocks included nine named Cornell-Geneva clones [Geneva® 11 (G.11), Geneva® 30 (G.30), Geneva ® 41 (G.41), Geneva® 202 (G.202), Geneva® 214 (G.214), Geneva® 222 (G.222), Geneva® 890 (G.890), Geneva® 935 (G.935), and Geneva® 969 (G.969)] and M.9 NAKBT337. All trees were spaced 1 x 3.5 m and trained using the tall spindle system. After 5 years, the greatest mortality was for trees on M.9 NAKBT337 (14%). Rootstocks separated into size classes from large semi-dwarf to small dwarf. G.890 resulted in large semi-dwarf trees, and G.202 produced moderate semi-dwarfs. G.41 and G.30 resulted in small semi-dwarf trees, and trees on G.935 were large dwarfs. G.11, G.214, G.969 and M.9 NAKBT337 resulted in trees that were moderate dwarfs, and G.222 resulted in small dwarf trees. The most yield efficient (cumulatively, 2016-19) trees in the trial were on G.935, G.11, and G.969, and the least efficient trees were on G.202 and G.890. The largest fruit (2016-19) were harvested from trees on G.30, G.41, G.890, and M.9 NAKBT33, and the smallest were harvested from trees on G.202.