What experimental rootstocks for apples are being looked at in the U.S.?

Many apple rootstocks are being evaluated for potential use in the United States by the NC-140 Multi-State Research Committee. These rootstocks have come from breeding programs in the United States (CG, G), Great Britain (M), Germany (PiAu and Supporter), Poland (P), Czech Republic (J-TE), Japan (JM), and Russia (B). Specific rootstocks that are currently under evaluation in NC-140 plantings include the following: B.9, B.10, B.7-3-150, B.7-20-21, B.67-5-32, B.64-194, B.70-6-8, B.70-20-20, B.71-7-22, G.11, G.16, G.41, G.202, G.935, CG.2034, CG.3001, CG.4003, CG.4004, CG.4013, CG.4214, CG.4814, CG.5087, CG.5179, CG.5202, CG.6210, J-TE-G, J-TE-H, M.9 Burgmer 756, M.9 Nic 29, M.9 NAKBT337, M.26 EMLA, M.26 NAKB, P.14, Supporter 3, Supporter 4, JM.1, JM.2, JM.4, JM.5, JM.7, JM.8, JM.10, PiAu 9-90, PiAu 36-2, PiAu 51-11, PiAu 51-4, and PiAu 56-83. Rootstock evaluation is a long-term project, with each planting evaluated over 10 years for tree survival, yield efficiency, and tree size (along with other traits). It then takes additional years for superior rootstocks to enter commerce.

Dr. Wesley Autio, University of Massachusetts, Amherst