Subdue maxx (fungicide)

[nancy]

Well, my friend ponied up close to $300 for a quart of this, and gave me a couple of ounces. I have downloaded a copy of the label, and the usage rate is about 15 drops per gallon (or about 5 drops for my little pressure sprayer).
Has anyone used this on orchids? Specifically I want to treat Guignardia Leaf Spot caused by Guignardia species on vandaceous orchids.
Most of us in the deep south, especially along the Gulf and Florida coasts, are familiar with this apparently airborne fungus that has our foliage resembling the texture and color of an emery board after awhile...every time a hurricane blows through, this fungus seems to come with it.
So, my questions: did you use a buffer/spreader to adjust pH? I had planned to spray the affected foliage only, and also saturate the roots, since I believe this is at least slightly systemic.
Any tips very gratefully solicited. Or any thoughts.
Regards - Nancy, queen of the unsightly fungus