This is definitely something for Ray.
In the meantime, maybe you can take a look at the following text by Sue Bottom:
http://www.phelpsfarm.com/OrchidPestsandDiseases.pdf
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Sorry to bother you all with these ugly leaves. Hoping for advice on what these ailments are and hopefully one treatment for them all
The first two pics on my vanda types, second cattleya and last oncidium.
This is definitely something for Ray.
In the meantime, maybe you can take a look at the following text by Sue Bottom:
http://www.phelpsfarm.com/OrchidPestsandDiseases.pdf
Hah! I was going to refer you to that, as well, although at the St. Augustine Orchid Society website.
My take would be acidovorax, which is a pseudomonas infection. Sue Bottom’s article recommends Physan or a copper compound, but I’d recommend the latter - Southern Ag Liquid Copper, Phyton 27, or others - as Physan is a topical treatment only, so won’t actually cure internal infections.
Such bacteria are ubiquitous, and there is little one can do to eliminate them in the growing environment. In the greenhouse, I periodically wetted-down the structure, floor, and benches with Physan or bleach to knock down the population, but I have found that regular use of plant probiotic products (live, beneficial microbes) to be a boon for preventing such infections.
I currently use Quantum-Total (also sold as the privately-labeled “Quantum Orchid” at a much higher price) and am quite pleased with the results. Not only am I seeing virtually no rots or disease symptoms on my orchids (growing on my deck for the summer, since I have no greenhouse here in NC), but the same is true for bedding plants, tomatoes, vegetables, etc. This year is supposedly a bad one for rust on figs, but I have not seen a trace of it on mine.
Take a look at What Do Plant Probiotics Do.
Quantum is a plant probiotic. It does not contain copper, but it contains live microbes that predate pathogens, among other benefits.
We relocated permanently to NC just shy of 5 years ago.