On another forum, a member posted a link to a German orchid website that has a section about diseases that affect orchids. The section explains each disease, whether its bacteria or fungus, also viruses, and non-pathogen related damage and symtoms, and also how to control pathogens. Most have photos of the symptoms in various orchids. I found it to be excellent and helpful, and I hope you do too. Here's the link:
http://www.hark-orchideen.de/Pflanze...ng=en&navID=99