Stems and leaves are attacked. Yellow or orange spots develop on the leaves then gray pustules form on the undersides of the spots. The pustules may be gray under some conditions. The leaves may develop holes when the pustules drop off. The fungus overwinters on the basal leaves and old stems.
Control includes good sanitation.
Clean up the old leaves and remove infected leaves as they are noticed. Cut back the plants immediately after flowering. Chemical control is achieved with sulfur. Visuals associated with this text. This information is for educational purposes only.