I discovered a Cat. a couple of months ago that had two of these lesions on one leaf. They appeared to be Bacterial Soft Rot. They were evident only on the top of the leaf. The bottom-side looked fine. I dabbed hydrogen peroxide on the lesions, repeated the application the next day, and then sprinkled cinnamon over the area. I did not cut away any tissue. The lesions now appear about the same, but are "drier-looking". They did not spread (a yellow hallo around the lesions never has formed) and the bottom of the leaf still looks normal. I have this particular orchid out front and on a lower shelf so that I have to look at it every time I visit the greenhouse.
