Question
I read in another reply that spring frosts won't hurt this rose unless it continues for 3 consecutive days.  I hope that will prove true but I'm fearful.  My tree rose, planted last fall, came through the winter beautifully.  A week of unseasonably high April temps (in the 80's) had it near blooming by the 1st of May.  But then we had a killing frost.  I thought nothing of it until my baby started wilting a week later & would not stop going down hill.  Now all leaves are crunchy.  County extension service said this sounds like classic frost damage & to watch for blackening of the branches to determine extent.   Here are my questions:  The blackening (just slight)is on the "trunk"- does that mean I have lost the whole tree?  Or should it recover?  If the tree is lost would the root stock likely come back as anything worthwhile? How long should I wait before pruning the crunchy branches?  How long until I should give up on recovery?

Answer
When a rose gets frost bitten, the new growth is frozen and goes crispy and then new leaves start to grow behind the dead ones. Also if the canes get frosted, the outer bark gets killed but the inner may still be alive. Before you cut anything, take your fingernail and scape the canes to see if the colour is green under the dead looking bark. If it is then leave the rose alone as the new leaves will push off the dead ones. If the rose has been totally killed then there will be brown inside the bark. You could also cut the canes a little to see if the inside is still green and if it has brown in the centre, just keep cutting until it is a pale green colour as this will be normal and grow well.
Tall rose trees are made by growing a Rugosa rose to the desired height and then rubbing off the side shoots as they appear. Finally they bud the Knock Out rose on the top. Therefore you would get a Rugosa rose from the base when the tree is dead. However if the tree is only around 24 inches, it could just be a totally  Knock Out rose and the new growth would be true.