Neem oil is supposed to be effective against rust.
Rust is a major problem for snapdragons but I never thought to use neem. It really does help with mildew & aphids on the roses, however. Green beans sometimes end their season because of spider mites. They usually show up on the bush beans and I am not much concerned about pulling the plants. Pole beans have a longer season or, should have.
I have kind of drifted off the subject of rust on beans. Maybe neem oil would help, '4acres.