Is this a virus on my Cattleya?

I have another older Cat that is behaving as my sick cats did a year ago. Unfortunately it was separated from its tag so I cant' look up the culture.

The bottom of the sheath is jet black, as is the base of another trying to come out. The bottom of the pseudo bulb where it meets the growing medium is black. I've had this in semi-hydroponic for over a year, and it's been happy -- until now.

We just installed a tiny greenhouse, and I moved half of my cats into there and kept the other half in the house to see how they adjusted. I'm in DC and temps here have been in the 90's. I can keep the greenhouse in the 90's with shade cloth, but I haven't been diligent about keeping the fan going. Most of the other Cats are happy, and my Oncidiums really love it.

Should I cut the whole stem off -- or should I just throw this away, too.

Sorry for the lack of focus -- it's my husband's camera and I couldn't zoom in much.

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I think I'm looking at something that is caused by lack of air movement and too much wetness. How is the environment inside your greenhouse? To be honest, since this plant is growing in S&H which provides good constand moisture to the roots, I find that the vegetative part of the plants usually perform better if they aren't kept as humid. I have all my plants in S&H, and in my apartment my hygrometer usually always reads between 50 and 70% humidity, and my plants are doing exceptionally well...no rot, no mold, no nothing. Also, they have a fan on them all day long. Essentially, stagnant air and moisture = rot and mold, so see what you can do to improve the environment in your GH and you should do better. Do you have any fans in there? Can they get some fresh air? Things like that

I forgot to add: Don't cut that growth off yet...if you lower the humidity a bit and increase the air circ, you might be able to save it. Is that brown stuff mushy or crunchy? Raised or flush with the leaf surface? Its hard to tell from the pic - it could also be sunburn? If you tell us more about your GH environment, that would be good to help us determine the proper course of action.

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