I sort of freaked out. It could be the normal aging when old leaves die, but what if it is not. Orchid forum members pointed out that bark pieces used for potting are too large and maybe they don't retain enough moisture. Also maybe roots are dead and rotted?
To check the roots I pulled my oncidium from the pot:
Well, they are not the best but also not all dead and have plenty of new growing points.
I was also worried about Psychopsis that is potted into same large bark, so I pulled it out too:
Psychopsis roots seem to be fine also.
So I just picked the large pieces of bark out from medium and added a handful of coconut husk chips to the mix instead:
Then I potted both plants into their clay pots with new mix. Hope it will help to retain more moisture. I am not sure if I should remove yellow leaves or just let them be and they wll dry out and fall off at some point.
