My guess, however, is that black spot has little to do with your winter die off problem. Roses in pots are much more susceptible to extremes in temperature -- hot or cold -- than roses in the ground. There are many posters here living in colder climates who have had success overwintering roses by giving them protection and/or insulation. Moving them into a garage or barn is one (backbreaking) way. Surrounding them with some type of mulch -- hay or compost, etc -- and covering them with a protective tarp so it doesn't all blow away is another. Surely there are other techniques that are even more clever. There was a thread about this a little bit ago, but I can't seem to find it at the moment.

Kay

PS: To keep roses in pots happy, they do need to be in containers that are quite large. It also helps to change out the potting soil every couple of years.

I asked a question here a while back about disease resistant roses for containers and searched past postings. Several people recommended Kordes roses sold by Palatine Roses. There certainly are some beauties, including several hybrid teas. I plan to try Lasting Love and Beverly in larger containers this summer.

Sheer Bliss and Pink Promise are outstanding Hybrid Teas in a cold zone. They reach four feet tall here, shrug off winter.

Pink Promise holds onto its leaves better than some other Hybrid Teas.

Perfume Delight is relatively new to the garden, planted last spring. It was exceptional last summer, a bloom machine, and well foliated.

Frederic Mistral has also done well, it grows larger than sonme other Hybrid Teas.

Unless a rose is really unhealthy for some other reason black spot rarely kills a rose. So I doubt that's what killed your roses. More probably they died from freezing and thawing repeatedly over the winter and early spring. Where are your potted roses located? Do you do anykind of winter protection on your pots? Because their root balls are above ground potted roses have to have winter protection. Can you move the pots to a protected area for the winter? A shed, garage or out building of some kind would work. I don't have any of those so I keep mine against the back, south facing, wall of my house. They are grouped close together, wrapped in burlap and packed with leaves. This has worked for me for 5 winters now and I've rarely lost a potted rose. I've lost far more in the ground than I've ever lost in the pot ghetto.

Kay- there definitely are two issues here. I have tried various things. My garage is heated, so I knew that was more or less "out". Have a small attached unheated greenhouse (which my son wants to tear off). Had them in there last year and three close to the door did not survive, four others did. They did not survive in a small unheated barn, mostly because I could not get out there to water, so won't try that again. Because I had surgery this summer,my DIL took three that I had, put them in the ground and covered well. They were covered with leaves, but considering our weather,I doubt that now..

Krista, noticed you were Zone 4. I simply have not been able to grow Sheer Bliss although I love the color. We just get too much extremes here.

Seil, you must really have a green thumb to think that you have had such good luck just having them up against the house (that didn't work for me either). I certainly don't expect perfect blooms and am happy with moderate foliage but sweet blooms. Having had a melanoma several years ago, I definitely abhor the various sprays they have. I am a member of the Cherry Capital Rose Society because I believe they have helped me the most.We have not had so much snow that it keeps the roses pretty well acclimated, which I do think makes a difference.
Thanks everyone. I really appreciate the imput. Barb