I decided to salvage what I could of my apparently dying rugosas, species Alba & Rubra (see previous post). I dug in to collect and transplant viable suckers and cut out all the dead stuff. What I found was something resembling an old bed of iris: lots of suckers over-lapping each other with very few roots.
Both plants had started as bands 9 years ago and grew into a large thicket. The core plants have stopped producing new growth; only suckers are left. There are few/no roots to them; they just travel underground, but close to the surface, for 6-18 inches, sprout up, bloom, then die. There was a whole mess of old suckers. There were also what appears to be new core plants, ie, really rooted in a couple places, so I left those. We will see if they die back or can now flourish because I cleaned out all the dead suckers and old dried up canes. Also, I don't think they like the soil. It is clay with a lot of gravel mixed in from the side of the driveway. I thought when I planted them there that they would be okay because rugosas come from rocky areas. I think it is the clay they don't like, as some suckers/roots were rotted, and that I've had similar problems with other rugosas in other areas.