That's right, ringing a bell now. Sorry, didn't re-read the entire thread.
At one point you said said,
"Suddenly the white mildew spread on my African Violets. Someone here said it was impossible. They said that powdery mildew is different for each plant. For instance, powdery mildew on an orchid is a different species of fungus versus what could grow in the African Violets."
In hindsight I'd totally agree with CPPgardener.
I know powdery mildew, if that's what the orchid had, can be carried in soil but don't think it grows on it the way it does on leaves.
