Cattleya dowiana new growth turning black?

[brsucculents]

This is an excellent question.
It looks like black rot to me.
For the immediate action, I think Katrina gave good advice. Cut the stem back till you don't see black or brown. Sterilize the blade between cuts and use cinnamon. I would try to cut it off above the rhizome so the eyes can initiate new growth. I think the black stuff at the rhizome is just the sheath. It can be pulled off.
The root cause /or prevention is the real question. I had a real problem last year. I treated eveything with a very expensive systemic fungicide for black rot. There is a lot of information out there that this is related to low Calcium. I use rain water to water my Orchids which contains no Calcium. I now alternate with my regular fertirlizer with micro nutrients and Ammonium Nitrate/Epsom Salt/Cal-Mag. This seems to have really helped the problem. But I recently noticed some brown shoots.
What's the cause of the recent problems? Has the systemic fungicide worn off? Has all the rain eliminated the Calcium in the media (I grow outside during the Summer)? I suspect the plant isn't getting something it needed and aborted.
I would greatly appreciate the input of other more experienced growers.