Infected leaves are picked off and burned. No chemical control is listed. Leaf spots can be caused by various fungi. These are usually not serious and no chemical control is listed.
Powdery mildew causes forms a white coating on the leaves.
This disease is controlled with applications of benomyl of sulfur. 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.