I have read in some other orchid forums a spray of Listerine, the original formulation, can be used too. Then plant has to be kept dry to recover.
One of my noid Phals, also had something similar when I got it as a gift, but I did not do any spraying on it, just kept it drier than most. It took awhile to recover, seems really nothing was happening, but those blackened spots did not spread nor further hurt the plant. A new leaf has now grown, so I am reassured plant is recovering. Still keeping my watering at root zone level, nothing on the leaves. I have all my Phals indoors. I am waiting for the plant to just naturally drop the leaf. It is on the lower part, so am sure it will do it pretty soon.
