Brown spots on leafs and spreading

[Lahra]

On the under-side of my Phals small dark brown spots started appearing. The spots make the tissue of the leaf collapse, they grow and later appear on the top of the leaf too. It looks like something is eating the leafs from the inside out. The roots are healthy. They start out looking as a sunburn, but they're not exposed to direct sunlight so that's ruled out and it's definitely not from over watering either.
By the time I noticed this it spread to the neighboring plants. They're all quarantined now.
Can someone please tell me what is this disease?
Can they be saved or should I just get rid of them?
Thank you.

[Eyebabe]

This is likely a fungus.
Most leaf spot fungi can be killed with a treatment of Cleary 3336.

[Lahra]

Thank you for the tip.
Here is my follow up:
Cleary 3336 >>> I could not get it locally. Neither Lowes, and Home Depot nor the local garden center carries it. I looked it up online ... $65/gal (I found it expensive)
I bought EcoSmart Garden Fungicide (at Lowes) -> did not help. 7 days later I throw out 7 plants.
I have 3 more plants that are slightly infected>>> treating them with Physan (since I have it available) before I invest into Cleary 3336
I'll keep you posted.
If you have an affordable source for Cleary 3336, please let me know.
Thank you very much.

Lahra

[Eyebabe]

I got mine from rosemania.com
Zyban fungicide has the same spectrum as Cleary 3336; it is a copper base broad fungicide.
With the rapidity of spreading, this could also be bacterial.
Pseudomonas is a bacterial infection that can spread quite rapidly. You can treat that with Phytan 27 which is worth a shot imo especially if the fungicides are not working
Keep us posted.

[Lahra]

Due to my busy schedule at work I wasn't able to spray the remaining orchids regularly with Physan, so this disease was spreading - at a much slower rate though. 3 weeks later, I noticed some similar spots on my small avocado tree and my desert rose and I through them out immediately.
I only have 2 more orchids that are still slightly infected.
I'm concerned about the environment when using Physan, so I thought I'll try something less harmful. Spraying my orchids with silver solution and rubbed iodine over the brown spots on the leaves.
I'll keep you posted on how this works.

[Zoi2]

Just my 2 cents worth: keeping the leaves wet without good air circulation will cause this.
Joann