Which rootstocks are winter hardy?

Rootstocks can affect the development of cold hardiness in apple trees, but this is a complex trait, and it may depend on what time of the winter with which one is concerned. Some rootstocks, such as Robusta 5, can cause a tree to harden early in the winter, and these trees are very cold tolerant during the early winter. Some rootstocks, such as Robusta 5, that induce early cold hardiness also lose their hardiness early in the winter in response …

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, …

How do nurseries grow rootstocks?

Rootstocks are commonly propagated by layering to form large stool beds. The “mother plant” is set out in the field. The plant may either be mounded, or it may be trench layered. In mounding, the plant is cut off close to the ground. As the new shoots emerge from the mother plant, they are partially covered with soil or well-decomposed sawdust. The sawdust is renewed periodically during the growing season to prevent the base of the shoot from exposure to …