I missed the original post but it seems to have something to do with
mildew forming on indoor plants.

FWIW, I have had some success with powdery mildew (outdoors) control on
Zucchini using Oxidate, a commercial preparation of hydrogen peroxide.
Sprayed on the plants at a concentration of 0.1 to 0.3% it kills powdery
mildew if it hasn't completely covered the plant. Heavy infestations may
take two applications. Grocery store hydrogen peroxide is generally
around 3% concentration, so dilute it 10:1.

I've tried it on shower curtains also, but with less success. However at
the 0.1-0.3% level I haven't observed any harm to plants.