New Catt - Sunburn or Black Rot
 

I just bought this Catt last wknd. The owner of the shop told me it was sunburned. I have researched orchid diseases and found black rot and thought it may be that. I have moved it away from my other chids but would like any input as to what it may be. Thank you in advance. I am newbie and have fallen for these plants. :) Courtney

If it is sun burn it must be pretty severe. The main thing that is concerning me is the 3rd leaf in the first picture. It looks like that the issue is traveling up the leaf. It could very well may be a form of rot, But I by no means am an expert at this. I really hope it is not rot. But great job by moving it completely away from your others.

good luck.

Black rot moves very fast. I've had an entire pseudobulb turn black from blackrot in 24 hours. It also doesn't look like sunburn to me. My guess would be some kind of brown rot fungus or bacteria. I would cut it off, well into the healthy tissue. If you're lucky, it may not spread to the rest of the plant. Then give the plant some TLC and see what happens. Good luck.

Thank you sooooo much for the response. I will try your recommendation. I appreciate your diagnosis.