Problem with Psychopsis mariposa 'Green Valley'

[Susie11]

Originally Posted by estación seca

What are your day/night temperatures, humidity? What kind of light? How are you watering?

It's out of focus, but at the base of the pseudobulb in the photo with the brown leaf - do I see white cottony material?

Sorry about the poor quality pic but that white dot is diatomaceous earth. My day temps are high right now about 34°C and night time is probably only slightly lower. Current humidity is high - ish about on average 50°C to 65°C. I grow her on a south facing window. No shade.

I have had her since 2012 so she has weathered many storms with me. She was fine, really great root system. I just can't think.