It would be very helpful to know where you live and what zone you are in so we can give you more specific advice.

To tell if a cane is dead or alive snip off a short piece and look at the inside. If it is a greenish white or lite cream color and looks moist it's alive. If it's a brown or dark tan and looks dried out it's dead. Keep cutting back in small pieces until you get to that whitish center. From there down the cane should be OK.

Are you using those rose cones to cover your roses? I don't recommend those because in order to get them on you have to prune the roses very short in the fall. You should not prune your roses in the fall unless they are extremely tall. Even then you can stake them instead of cutting them back. Roses store food for the spring in the canes and by pruning them off in the fall you are pruning off all their food stores. Roses should be pruned in the late winter/early spring. The cones also create an environment that is just right for growing fungal diseases. Your roses may have been kept too moist and now have canker.

This has been an unusually cold winter in many places so it is possible that your roses did not survive the polar vortexes as well.

I agree with everything Seil said about your roses, and this may be one of those learning experiences to see what roses like in your zone. Nowhere do they like being without air circulation, which is what those rose cones and some other kinds of protection can provide, so the canes that are black are dead and need to be cut off. Whether the rose itself is dead remains to be seen. As Seil said, cut off cane until you see creamy white/tan insides of the cane, but don't cut below the knobby chunk at the bottom of the rose - assuming it's a grafted rose, this knobby part is where the rose you want starts, and pruning below it will only leave a different root stock behind. As long as some cane is still alive above that graft, or even at the graft itself, the rose will come back and you might never know it was cut back by mid-summer.

For fall protection next time, you may want to check some old threads or post a new one in September or October and we can coach you in some relatively straightforward ways to protect roses with better odds for survival. Of course, in cold zones there are some roses that won't survive regardless, so it might not be the cone's fault.

Cynthia

Thanks to you both for the advice. I will try the cuttings to see if I have any good rose left.