sick dendrobium
 

I would appreciate help identifying a disease on my dendrobium. It had been healthy till a few brown scale made a home on the canes last spring. I removed the insects and it has been bug-free since, but I noticed some molting (light green discoloration) on some of the leaves. It recently bloomed, then once all the blooms were opened for a couple of days, they started turning white/clear and falling off. Then some of the molted leaves started turning yellow and falling off. One other dendrobium next to it has also started to exhibit these issues. I have been spraying it with Physan 20.
Is this bacterial, fungal, or viral?
How else should I treat it?
Thanks for your help,
Jeff