Cool insight about the epsom salt. But using it straight is a bad idea to begin with. Just sits there waiting to burn unsuspecting roots. Watered-in or diluted and sprayed is a much better idea.
On my roses I used to use the...what is it...? Black mold spray, I think. But I live in the desert, and don't that problem any more. :thumbsup:
I think if we can identify and correct what's ailing his NL, any additional spraying would be unnecessary. Plus, spraying unnecessarily might cause more heartache than relief, ya know...?

It might be that in the long run, mold or mildew spraying is necessary. But unless it's an emergency, I'd rather see him fix the problem rather than masking it up. :thumbsup: