British Columbia: Help! failure of newly rooted rose cuttings

Hi

I am scratching my head over a problem that has killed (so far) all but one of the 4 successfully rooted cuttings I took from an old, robust, glorious Peace-type rose in Nanaimo BC. I brought the cuttings with me to Cortes Island with the intention of propagating this favourite variety; allowed them to root in the warmth of the wood-heated house, then "hardened them off" in a non-insulated greenhouse as Spring warmed up a bit.

well, it's been a sad story. all but one of them have followed the same path. first they seem to thrive, putting out a couple of nice leafy shoots at the top of the cane. the leaves go from pale green / pinkish and wrinkly to dark green, smooth and glossy, responding well to sunlight. everything looks good, except that meanwhile the green cane is starting to blush pink, then a darker red. no additional budding occurs any lower down.

as the cane reddens and darkens, the nice glossy leaves start to curl. their edges curl under (not up) and they droop a little. eventually the outer edges of the leaves themselves redden a little, acquiring a dark copper/red blush. then everything wilts and the end comes quickly. leaves drop off. aaargh.

the stem then turns black, from soil level on up. the blush on the stem seemed to come up from the soil level also.

I have been googling around and have not found any rose disease description matching this series of symptoms. what have I done wrong? I have propagated roses before (in a different climate) and succeeded. I've never had them die *after* successfully leafing out at the tip. these have been transplanted a couple of times, from a temporary pot into individual pots and so on, but I got away with this before too. I am watching the last of these cuttings now rather closely, and I fear I see the telltale blush starting on the cane.

can it be saved? what the heck is this -- disease? fungus? nutrient deficiency?

a clue would be nice, even if it's too late to save the last one.