The leaves turn brown in spots and the upper leaf surfaces stay green or turn purplish brown. Young stems and flower stalks are infected and killed. Use sprays of benomyl or sulfur. Rust causes rusty brown pustules on the leaves. The pustules are most noticeable on the undersides of leaves.
Infected leaves dry up and become brittle.
Sprays of sulfur control rust. This information is for educational purposes only. References to commercial products or trade names does not imply endorsement by MSU Extension or bias against those not mentioned. This information becomes public property upon publication and may be printed verbatim with credit to MSU Extension. Reprinting cannot be used to endorse or advertise a commercial product or company.