I've got galls by the hundreds mostly on Citation rootstock. Have for many years. So far it has had no effect on the trees or crop that I can tell. I am moving to other roots and replanting in the same places. There isn't much else I can do since it's in my greenhouse. I'm not too worried since the fruit continues to be great.

Several years ago I tried to buy Gallex. I got no where. As I recall, the one company that had had it no longer had it and said it was only for commercial use. Good luck, and I'm really interested if it is available at all. Sort of on topic, a well known rosarian from Mobile once in a talk said he had crown gall on all his roses and it didn't bother them, he just fertilized more. (At that time I had had a rooted cutting die, strangled by crown gall the size of a Cheerio, so I doubted him, but he may have found something that worked for his growing conditions.)

If your winds are so strong they're snapping canes off from the base even without the weight of leaves and flowers, you should bury your roses more deeply. I once had a rose do the same, snap off right at the graft on the last remaining cane I had. Killed the rose, of course. I wish I have buried it deeper to protect it from our strong winds. I don't know anything about crown gall though, hopefully someone with more trained eyes can help with that.

Can we see photos?