Do not put in the compost pile. Spraying sulfur controls rust. Leaf spot causes angular grayish spots scattered over the leaf. The dead tissue falls out leaving holes. Remove and destroy plant cuttings at the end of the season.
Powdery mildew covers the leaves with white powder growth.
Applications of benomyl or sulfur control the disease. Make sure that you properly identify the insect or disease before using any chemicals or they can harm your plant. Also, make sure to follow the pesticide label instructions carefully.