I think "Safer's" makes a spray fungicide that uses sulfur as the
active ingredient.

Many years ago, I used some Frasch sulfur from my rock collection
to clear up mildew that had absolutely covered the medium in which I was
growing at the time (tree fern- circa 1985). It worked very well, and had
no discernable negative impact on the phal seedlings.

The address in the header doesn't work. Send no email there.

-AJHicks
Chandler, AZ