Palatine, for example, uses multiflora rootstock. They grow their multiflora plants from seeds precisely because rootstock grown from seeds is virus-free. Rootstock propagated vegetatively as must be done with, say Dr Huey, is only as clean as the plant from which it was taken.
I tried to explain a little earlier: I think the reason multiflora rose is considered a vector for the virus is primarily because it is one of the few roses that satisfies all three of these epidemiological criteria:
1) it gets the disease
2) it thrives in the wild, growing on for a while after being infected, and
3) it was widely planted in the wild.
Most cultivated roses, I think, will get RR but most do not satisfy the last two conditions. I don't have any reason to believe that a healthy multiflora plant near a garden poses any more risk than a healthy version of nearly any other rose cultivar. Except, perhaps, a cherokee rose which is not bothered by the mites that spread the virus. (That said, I think there are a lot of better choices for a zone 6 rose garden than a white multiflora rose.)
Keep an eye on the cane that is growing quickly - the one with the deformed leaves. My personal guess is that the fact that it is growing quickly explains both the purplish color and the deformation of the leaves. If, when it stops growing, the deformation and the coloration persist, photograph it again. Start another thread here. And start preparing yourself to destroy some roses.
