Oh darn. Well I'm pinning some hopes on a new fungicide I'm trying - a biologic called Actinovate rated organic and even safe to use on food. So I've sprayed my daylilies, plumeria, cannas and my fig tree. We shall see! The UF boffins who tested it had "miraculous" results against both powdery mildew and rust.
Also trying it on my orchids . . . who knows, it may be the silver bullet for the black spot diseases.