Lindsay, it sounds to me like the only thing that stops the spread of the disease once it's got a hold is removing every bit of affected tissue you can, then keeping the areas where it was dry, dry, dry after that.Systemics will help keep the healthy tissue from infection, but won't cure it once it's going. I'm thinking the cinnamon treatment worked for me because it's applied dry. The others are all either sprayed or doused on with water and any more water was the last thing I wanted to put on my sickly plants.
Just a thought, since there's no sign of black spots on the leaves, and there is healthy looking new growth, what about re-potting? Getting rid of as much diseased tissue as possible must be a good thing, right? Take it 'way down the far end of your garden (downwind of any other orchids, preferably) and removing the plant from the pot, you might spot any more blackened areas such as roots, and be able to excise them, too. Get rid of the old medium that could be holding spores of the fungus - put all the diseased plant stuff and medium in a sealed plastic bag in the trash. Douse the naked plant with whichever fungicide you get, then dust every part of the lower portion of the plant especially the cuts with cinnamon, and re-pot with new (dry?) medium and a sterile pot. Then let it dry out for a week, maybe?
What do you think, experts?? Is drastic action justified here?
