don't mean to be a wet blanket here but I believe you are seeing winter damage. the culms that are still green with green leaves, including the branchlets, look like they may be able to leaf back out. the tan ones and the mostly black one - pic 3 i believe, are likely dead. the black is cold damage, and with rubro the more black the more likely that culm is dead in my experience. keep an eye out for new, elongating leaf buds as a sign that the culm is still alive, on a young rubro plant like this in PA, i suspect you'll see new shoots in 2-4 weeks.

Thanks Inversa,

So in your opinion both, the yellowing and black discoloration, are due to winter damage? This would be a relief as I was fearing I had both, winter damage and a drainage problem!

My real immediate concern is that while heavy fertilizing and watering over the last week has begun to reverse some of the yellowing, the black discoloration seems to be getting worst. That is, unless I just didnt notice it all before due to my recent obsession over saving them ;)

Thanks again for such a speedy response.

amb-
It sounds like winter damage to me. too. You will get new leaves, but any change in the culm color is not going to be reversed. (P.S.: it's "culm," not "clum.")

Thanks for the feedback kudzu9. I'm disappointed to hear the black coloring will not reverse itself (although the yellow culms have definitely been turning back to green recently). However, I'm thrilled to hear that I dont have 15 dead bamboo plants!

Thanks also for the spelling lesson ;) I must hav mispelld that a thowsund tymes over the past few munths.