Commercial orchard evaluation of the new Cornell-Geneva apple rootstocks

Ten replicated field plots were established on growers' farms across NY state to test the new Cornell-Geneva (CG.) rootstocks which have resistance to fire blight and to Phytophthora root rot. Each trial has from one to 15 CG. rootstocks and appropriate commercial rootstocks as controls. Early conclusions after 5 years are: 1) Geneva 65 (G.65) trees are significantly smaller than M.9 trees. Without irrigation, 'Empire' and 'Liberty' trees on G.65 have been too weak with insufficient leaf area for optimum fruit size and have generally had lower yield efficiency than trees on M.9. 2) Geneva 30 (G.30) trees are slightly more vigorous than M.7 trees but much more productive. After 5 years, trees on G.30 have had double the yield of trees on M.7 with yield efficiency as high as M.26. G.30 trees have moderate suckering. 3) Geneva 11 (G.11) is similar in tree size to M.26 and has performed as well as M.26 or M.9 through year 4 with 'Liberty' as the scion. 4) Cornell-Geneva 16 (CG.16) is similar in tree size and productivity to M.9. 5) Cornell-Geneva 210 (CG.210) is similar in tree size to M.7 or G.30; however, it has the added advantage of resistance to woolly apple aphid. Yield efficiency has been significantly higher than M.7 and similar to M.26. 6) Yield efficiency of CG.41, CG.935 and CG.707 has been greater than or similar to M.9. CG.41 is similar in tree size to M.9. CG.935 tree size is slightly larger than M.26 and has had the highest total yield and cumulative efficiency of any rootstock in the trials. CG.707 is a vigorous rootstock similar in tree size to MM.111 but is much more precocious.