Performance of ‘Golden Delicious’ apple on 23 rootstocks at eight locations: a ten-year summary of the 2003 NC-140 dwarf rootstock trial.

Dwarf apple (Malus spp.) rootstocks with ‘Golden Delicious’ as the scion cultivar were evaluated at eight locations in North America for 10 years. A core of 11 rootstocks was evaluated at all locations. Core rootstocks included four industry standards (B.9, M.9 NAKBT337, M.26 EMLA, and M.9 Pajam 2), along with B.10 (formerly called B.62396) from Russia, G.16, G.41, and G.935 from Cornell-Geneva, J-TE-H from the Czech Republic, and PiAu 51-4 and PiAu 56-83 from Germany. Some locations also received CG.5179 and G.210 (Cornell-Geneva), JM. 1, 2, 4, 5, 7, 8, and 10 (Japan-Morioka), J-TE-G (Czech), and PiAu 36-2 or PiAu 51- 11 (Germany). B.9 was less vigorous than M.9 NAKBT337 and J-TE-G was less vigorous than B.9. J-TE-G was too dwarfing for most commercial situations. Rootstocks in the M.9 size class included G.16, G.41, G.935, CG.5179, G.210 (formerly known as CG.6210), JM.1 and B.10. All rootstocks in this size class had high yield efficiency (YE), and G.41 and G.935 may be candidates to replace M.9 because trees survived well and had high YE. Rootstocks in the M.26 size class included J-TE-H, G.210, JM.7, JM.8 and PiAu 51-11. J-TE-H was the only rootstock with 100% tree survival at all locations. Cumulative YE was similar for M.26 EMLA and JM.7, it was slightly higher for J-TE-H and it was highest for G.210. Due to exceptional tree survival and high YE, both J-TE-H and G.210 deserve further evaluation as potential replacements for M.26. Rootstocks more vigorous than M.26 included PiAu 51-4, PiAu 56-83, PiAu 36-2, JM.2, JM.4, JM.5, and JM.10. All of these vigorous rootstocks had lower YE than M.26 EMLA and are probably too vigorous for modern commercial apple orchards. Biennial bearing increased with increasing trunk cross-sectional area at three of the eight locations, so factors other than rootstock vigor also influenced annual cropping.