See:
Note: There are many fungal and bacterial leaf spots of orchid but samples sent to the OSU Plant Clinic have mostly had abiotic brown leaf spots.
Epiphyllum sp. (orchid cactus) with oedema - an abiotic problem where subepidermal cells expand and protrude through the leaf surface.
OSU Plant Clinic image, 2010.
See:
Note: There are many fungal and bacterial leaf spots of orchid but samples sent to the OSU Plant Clinic have mostly had abiotic brown leaf spots.