In Kirra wrote:
How do you deal with this? Should I avoid dormant spraying these roses
or attempt to spray/pour right against the canes so that there is no
drift onto the companion plants?

Kirra, in the days when I was a lad (lol) and had companion plants, I
used a nice soft sponge dipped in lime sulphur solution and wiped the
bare canes with it.

Plenty of plants wouldn't mind lime sulphur, but then again plenty would,
too.

One tip - if you do this trick, use waterproof gloves. Otherwise your
hands will smell to high heaven for a week.