'Gala' Apple Trees on Supporter 4, P.14, and Different Strains of B.9, M.9 and M.26 Rootstocks: Final 10-Year Report on the 2002 NC-140 Apple Rootstock Trial

Abstract

In 2002, an orchard trial of apple rootstocks was established at six locations in Canada, Mexico, and the United States using 'Buckeye Gala' as the scion cultivar. Rootstocks included B.9 (North American strain), B.9 (European strain), M.26 NAKB, M.26 EMLA, M.9 Burgmer 756, M.9 Nic 29, M.9 NAKBT337, P.14, and Supporter 4. After 10 years, the greatest mortality was for trees on Supporter 4 (35%), and the lowest was for trees on M.26 NAKB (10%) and B.9 Europe (7%). P.14 resulted in the largest trees based on trunk cross-sectional area (TCA). Smallest trees were on the two B.9 strains. Largest trees in the intermediate group were on M.9 Burgmer 756, followed by those on Supporter 4, and M.26 NAKB, M.26 EMLA, M.9 NAKBT337, and M.9 Nic 29. Burr knot severity was highest on M.26 NAKB and lowest on B.9 North America, M.9 Burgmer 756, and M.9 Nic 29. Root suckering was greatest from trees on M.9 Nic 29, more than all other rootstocks. B.9 Europe produced significantly more root suckers than did B.9 North America. Trees on P.14, M.9 Burgmer 756, M.26 NAKB, and M.9 NAKBT337 yielded more (cumulatively, 2004-11) than did those on either strain of B.9. The most yield efficient trees (cumulatively, 2004-11) were on the two B.9 strains, and the least efficient trees were on P.14. On average over the first 8 years of fruiting, the M.9 strains resulted in larger fruit than did the B.9 strains. B.9 North America resulted in significantly larger fruit than did B.9 Europe. Additional rootstocks tested at a small number of sites each and included in this report were CG.3007, G.41, G.935, G.11, JM.1, JM.2, JM.7, PiAu 36-2, PiAu 51-11, PiAu 51-4, and PiAu 56-83.