Hypericum Rust.
Hypericum Rust H. calycinum is the tougher and shorter of the two but H.Hidcote has a sterile flower so produces flowers over a longer period. If you are looking for rust resistance, then H.Mystical TM Series has a new line of four rust resistant varieties.The best way to hinder the rust develoment is to shear back in the spring (especially in the case of H. calycinum) so that new growth is encouraged.Remove any clippings and burn.The rust, although unsightly is ususally not serious.