|Authors: ||T.L. Robinson, S.A. Hoying, G. Fazio|
|Keywords: ||Malus × domestica, yield efficiency, dwarfing, fire blight, fruit size, root suckers|
Two replicated rootstock trials on growers farms in New York State were begun in 2004 to evaluate the Cornell-Geneva series of apple rootstocks which have been bred for tolerance to fire blight and Phytophthora root rot, high yield efficiency and good tree survival.
In the 2001 trial with ‘Golden Delicious’ as the scion, the two named Geneva® rootstocks, G.41 and G.11 were dwarfing, had good survival and had high yield efficiency.
Other promising un-named dwarf selections include CG.4214, 6006, 5005, 5087 and 5012. Two semi-dwarfing selections similar in size to M.7 showed good survival and high yield efficiency, CG.6969 and 5890. In the 2004 trial with ‘Honeycrisp’ as the scion, the named Geneva® rootstocks, particularly G.11 and G.935 continued to perform very well but we have also identified a group of 4 new dwarfing rootstocks CG.4021, 4210, 5757 and 4214 similar in size as M.9 or B.9 which have high productivity and fire blight resistance.
We also identified a group of 6 semi-dwarfing rootstocks, CG.4001, 6969, 5757, 5046, 4004 and 5012 between the size of M.9 and M.7 which have high productivity and fire blight resistance.
These rootstocks are free-standing but will need trunk and limb support for the high crops which they produce in the early years.
These may be useful in parts of the world where fully dwarfing rootstocks are not adapted.
We also identified a group of 4 vigorous rootstocks, CG.6001, 7707, 5890 and 6874, larger than MM.106 which have high productivity and fire blight resistance.
These may be useful in the garden center trade.
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