Sorry you've seen leaf drop; usually too little moisture and too little humidity will do it for brassavola. Mounted, it's almost impossible to overwater them; provided you let the roots dry between waterings (they'll become white aside from the green/reddish growing root tips). Good culture on these; as noted above, mount bare (unless they have no roots when mounting them up, then use a sparse sphagnum pad), 45-70% rh, good airflow and high light (Laelia/cymbidium level; though you'll need to reacclimate your plant). Contrary to the others, I would not split the rhizome; like cattleyas, they are capable of throwing roots and budding vegetatively from damaged rhizomatic growth.


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That is one of the other reasons I put everything in red lava rock or have them mounted...I am not a fan of re-potting (that and I can kill anything in bark). :|

---------- Post added at 03:06 PM ---------- Previous post was at 02:54 PM ----------

It sounded like something systemic. This past autumn, I had something like this in my nodosa and split it to ensure that I would not lose the entire thing (did not want to spray Captan in the home). The one half continued to lose leaves and died while the other has continued growing well and will soon be blooming. I was concerned that the OP had the same issue.

I'm probably amiss in my thinking, but if it were systemic, I'd guess that the entire plant would continue to progress negatively even after the division was made. The exception, I believe, being newly developing growth--this is the reason you can replicate virus free clones via meristem from virus infected plants.

I've seen infections that seem to move from one pseudobulb to another of a Cattleya and saved orchids by removing the infected section...and lost them when I didn't. No idea. Just observation.