Phal Disease Spreading Fast: Virus, Fungus, or Bacteria?

[mbentley]

Dear Orchid Board Community,
I have a dear collection of many different types of orchids in my home, and recently, all of my Phals have started developing an unsightly yellowing (and then browning and cell collapse) in the foliage. The blight is spreading quickly. They have all succumbed within about 3-4 weeks. I have noticed one of my paphs is also displaying some yellowing, although it does not appear as dire.

I'm concerned that it is one of the dreaded viruses that plague orchids and that I will loose much of my collection. I have started preemptively treating with physan, just in case it is a fungus or bacteria. I have not done any pruning or cutting recently of any of the orchids, nor do I recall adding any new orchids to this particular table in the last few months. I'm attaching some photos representative of various stages of this ailment. I hope folks in the forum can help me identify what is killing my orchids.

Many thanks!
Merideth