I don't think it's crown gall either. Actually, it looks similar to what happened to my Jen's Munk rose; roots strangling each other. See the link for pictures: Here is a link that might be useful: Garden Musings blog on Jen's Munk demise.

We've been dealing with crown gall in the Sacramento cemetery. We seem to especially get it where roses have been infested with grass, and men have trimmed carelessly with weedeaters. But that's not the only place. I do believe that damaging roots can increase the risk of entry, and sometimes you only discover the gall when you dig up the plant and find out how infested the roots have become. It isn't always evident on the crown. However, we have dug up roses and moved them, with no visible problem. We try to leave the planting spaces where we've removed gall-infected roses fallow for several years, although I've heard that doesn't really assure that the bacterium is gone. I've also been told that it is systemic throughout the plant, so propagating a gall-infested rose is not wise. We try to practice good hygiene with our pruners, and to avoid getting dirt in contact with a pruning cut. Since our roses are planted fairly far apart, we have watched roses with crown gall and not removed them until they begin to decline. They sometimes seem vigorous for years but then suddenly die back. I've learned to look at roots of a sickly rose when we are removing it, because I often find gall or rot of some kind. In California, Cooperative Extension doesn't test soil, but we do test galls or other diseased parts of plants. I've had the crown gall confirmed on several of our cemetery roses, and think now that I can recognize it when I see it. Some of the apparent galls on the canes have turned out just to be proliferating growth that can develop when a cane is sunburned or damaged otherwise. No tobacco was ever grown in the cemetery, I guarantee it! Anita

At the arboretum we lost most of the original OGR's to crown gall; many reverted to their rootstocks. We took the precaution of changing out the soil when we replanted-- a huge job-- but we haven't lost a rose since. Despite keeping two complete sets of tools, I have lost several roses at home due to crown gall. I believe it's a coincidence. Will never know for sure!

Mine is an own root rose I got as a band in 2015 I think. I have not seen this before here. I understand some rose purveyors have sent infected plants and other people have the bacteria in their soil. I do hear you have to replace the soil where an infected plant has grown if you take it out. In theory, an own root potted plant might have less scrapes and wounds that the bacterium can enter. Some grafted and bare root do arrive pretty beat up. I remember reading on the forum that some people have gall on a rose that looks fine otherwise and if it was still attractive they just leave it. I have never read of it spreading all over from one infected plant. I have read of some commercial growers having their fields having a widespread infection with contaminated soil, sadly.