This is a new one to me, I have no idea if it would work with violets. The 'magic ingredient' I believe you are referring to is phosphorus.

Barbara

Sorry for the typo, should have been fosfor, phosphorus in English. Yes I'm sure that that is the idea but truthfully, I don't dare to do it with av's unless someone backs up this option.

Milli

Hunh. I've never heard of this. I do know you can use sulphur as an anti-fungal, so maybe that's it?

Good air circulation and an as-needed hit of Lysol can do the job too.

Korina

Mildew is airborne, not in the soil. So I don't see how that would work.

Neglected to mention -- even if the head of the match is aboveground, volatilization of the chemicals is nil to none.