Leaf spot remedies?

[Angurek]

I grow mostly soft-leaved orchids, so this disease is a problem for me. The spots come out almost overnight, and just mar the appearance of the plant.

The zygopetalinae are prone to spotting, so I know that, to an extent, some spotting is inevitable and normal. But there are spots that are raising red flags for me. Some of them start out as black spots, but then I notice a yellow halo or ring that develops around the said spots. After a few days, the infected leaves yellow and die. Thing is, the plants are perfectly healthy otherwise. They have good root systems, and the unaffected areas are lush and green. I've tried cutting off the infected leaves, but when I do, another leaf starts to spot. Go figure.

Anyone have any natural remedies for spotting? I want to try environmentally-friendly methods before I move to hardcore fungicides.