Yes, it's a continuing of the cold weather. I would have waited to plant until the weather is a bit warmer, especially for the night time temperatures. But, what you can do is cover them with card board or bags of shredded newspaper at night time. Or a great big sheet (not heavy)

Also leaving the door open in the garage on nice days was good, but I would have still been bringing the roses outside for the day and inside for the night until all the cold spells had passed. Don't be in too much of a hurry.

So, cut back to the green and cover at night - I think a light blanket/sheet is probably the best option. Don't worry about sealing the canes unless you have a lot of insect pests that might get into the open cane.

Good luck!
Carol

You might be transfering a fungus infection from infected canes to others with your pruners. I said "might."
You can disinfect pruners between cuts with Lysol spray, bleach, or alcohol. The bleach or alcohol can discolor the blades. Put in a spray bottle and spray the blades or in a jar with a saturated sponge and poke the pruner blades into the sponge between cuts. By doing it this way you'll avoid spilling the stuff if the jar tips over. Keep a lid on it after use to prevent the sponge from drying out and the produce used from evaporating. Liquid Lysol can be used also.
Make sure you're cutting just above a leaf. The section of cane above the leaf, if too long, will die back to the leaf or farther.
Sealing the cut can help also if the pruners aren't spreading the problem.

When did you prune? Canker attacks dormant canes--if you prune too early the canes aren't able to defend themselves. It can be a real problem if you have cold wet weather before the roses wake up. I just wait until they wake up, and then prune. Easy for me--I spent the early Spring moving big roses to the front yard. I've used Pine Sol and rubbing alcohol to clean pruners--bleach is too harsh on tools.

Here is a link that might be useful: Page on Rose Canker

Thanks Carol and Karl! It's only getting down in the fifties at night so I figured they were not getting any harm from the temps but thought they might be showing damage from the late freeze we got a couple weeks ago. I will definitely sanitize my pruners also. Its only happening on a few of them thank goodness!! Thanks again, Judy

Judy, I honestly think it is a result of drought plus freezes after a warm up in January that damaged the canes. I've lost a number of canes that appeared to be green, leafed out and then died. I clean my pruners so I know it isn't that.

Carol

When they are out of dormancy and cold damp weather persists you get dieback and canker that spreads and there is really nothing you can do about it. When it warms up for good this will end.

Thanks Zack, Carol and Henry! I knew last year, which was my first full year growing roses other than knockouts, this didn't happen once they started growing good. It only seems to be on a few of my newest roses and a few I moved last fall. Now that its heating up a little I hope it goes far, far away! Judy

I found a web page that suggests you may be able to control Canker with Daconil. But, the warning label says it can cause Severe Eye Damage.

Here is a link that might be useful: Good page on Canker

When we prune roses, often we only see one side of the bush. I often find that when an apparently healthy cane has died or started to ail after pruning, that when I cut it, I find a problem on the backside that I just didn't see the first time.

Now the color black isn't good. When it appears where you've just cut back, you've spread something to that surface. Clean secateurs are a necessity in our zone. (I've seen secateurs in zone 10 that could be called, at best, grotty and the owner never had a problem spreading diseases...probably because the fungi that are problems in zones 6-7 never reach our activation temperatures there.)

There is also the black that shows up when a fall cane gets killed by winter.

And there're big black splotches that rarely appear midsummer and need to be romoved quickly.