Welcome to NGA,
@discoflowers. It would be helpful to (at least) include your location. You can do this by going to your "Profile" and giving that information so that it'll show on all your posts.
If you only have a few plumeria, you can control, and sometimes even eliminate rust. Daconil works about as well as other fungicides and isn't terribly expensive. For best results, when you see rust on your leaves, clip those leaves off and trash them. Good luck!
