Hello,

Your daisies may be getting too much water. With the ample supply of water received recently in Southeast Michigan, that could be affecting your plants. Ensure that they are not waterlogged.

Be sure that they are getting plenty of sunlight and air flow as well. They may need be moved to a sunnier, dryer location, or perhaps even divide them if this is a large clump.

A similar question about Shasta Daisies also offers some additional insight:

“Some common diseases that affect shasta daisies (Leucanthemum x superbum) are alternaria leaf spot, septoria leaf spot, botrytis, powdery mildew, The treatment for any of these is the same.

Below are some cultural tips to help reduce fungal disease:

• Remove and destroy diseased leaves and plants at the end of the growing season.
• Keep plant tops as dry as possible by applying water to soil, not sprinkling over plants.
• Rotate planting beds.

It is difficult to properly identify the pathogen causing leaf spots. If you experience persistent problems (year after year) with the same type of leaf spot, it may be beneficial to contact your local extension agent and/or submit samples to a diagnostic clinic for diagnosis (http://www.pestid.msu.edu/). Once the pathogen has been identified, you can determine if control strategies are necessary.”

you're very welcome