Freeze damage is ruptured cells and they cease to function as cells for nutrient transport. Where Freeze damage happens, it is what it is.

Canker is more, in a bad way. (At least this is what I believe based on growing a lot of roses inzone 6-7 where winter can be kind only to turn merciless in early spring.)

Odd question, but important: are you colorblind? I ask because my husband is and there are reddish and reddish purple colors that he can't see. And that makes canker ID a whole lot harder.)

Canker is a (IMO) catchall term for fungus that thrive on dead plant tissue. But worse, there are fungi that don't need a lot to get a mycelia-hold fast (little mycologist humor there) to appear on a stem. Are the fungi active? Apparently some, maybe most, give off ethylene gas in large enough amounts to affect adjacent otherwise healthy cells. When those cells are affected, the color changes from green to reddish magenta. And it doesn't change back, even when the causing fungus becomes inactive due to heat/humidity.

I've seen Tea roses survive with only half a cane green an the rest dead . That cane will be weak but may last years, especially if supported. If you cut through a cane and see totally dead pith, then it becomes a learning experience: that pith will be crushed by the growth of the stem-unless the fungus has damaged the xylem and phloem system.

I think there are major variations from rose class to class. I don't understand Chinas, aside from Old Blush. Polyanthas are like their kin, except most of the kinships aren't published. Hybrid Teas seem really susceptible to winter damages, and to spring damages. there's a reason they were greenhouse grown a century ago and where they would be budded on the rootstock of the countryside.

If I were you, I'd choose to do autopsies on canes that you think are going to die and see what's happening inside them. I'd also check out some less healthy canes that you'd cut off anyway, and see if all the canes are looking fresh on the inside.

And then some of us are going to have to watch out for cicadas this summer and that's a whole 'nother set of symptoms.

Ann

Dear stillann. I appreciate the patience you have with my asking questions which are probably repetitious and simplistic. I do not believe I have ever experience freeze damage which explains some of my confusion. As Dallas heats up (85 yesterday), some formally green fat canes have turned black morphing down to black lesions that move down farther into yellow. . This is becoming evident on some of my large climbers. Our winter was warm so they were already pushing when the -4 hit. I am assuming the black to yellow is either freeze or a combo of freeze and canker. I had not experienced canker until it was introduced into my garden last year on grafted roses from one of our reputable online sources. They arrived diseased, they replaced but the several bushes later had canker reappear. I believe I spread it unknowingly.
Last week I cut black canes to good pith. Very scary on short thick canes so possibly I should have been braver with some cuts going farther down from black. On a few the pith was a healthy creamy color except for a pinpoint in the very center that looked dryer and more of a dirty beige. I thought these cuts were suspect but I left them.
I also have many strong healthy laterals braking on thick canes now exhibiting black farther down but on only one side. I have also left these temporarily, our summer heat will make the final choice on their sustainability.
No to the color blind. Interior Design was my life profession so lets hope not anyway.🙃 Vision going, back going, hair going, balance iffy, wrinkles coming but so far discerning color is still in tack... this year anyway.
I used alcohol to clean secateurs after cuts when I did my spring pruning which I assume is not as good as your alcohol sun suggestion. I assume the hydrogen peroxide that Mark recommended is also not adequate for canker. Thank you again and again for your advice and time responding.

BR

Austin my soul mate on 4 legs, still miss him.

I didn't really understand creeping black crud.

I got two same cultivar plants in both had it. I planted them in different rose beds and I didn't know how bad it could be.

One, I cut below the CBC three times one day, cleaning the secateurs bleach alcohol sun alcohol . And I photographed lady bud life cycles.

The second bush had CBC but not as bad so I left it as we were going out of town for a week. F'in disaster. The CBC moved much faster than I had expected it to and there was nothing left above the graft. Nothing.

A friend later was dealing with it on 'sublimely single', and she cut the black side of her only good cane off very meticulously cleanly. She then sealed the wound with tar. And the cane survived.

You might want to try some CBC excavation with exacto knives. And set up a rotation with the blades sun drying.

Also put on your rose calendar when the problem started. Very often the problems are temperature dependent and yearly patterns emerge over time.

Ann