Garden Pests and Diseases: Heliopsis Loraine Sunshine problem - black crusty centers, 1 by hollys_hints

hollys_hints wrote:
Is anyone familiar with this problem? Healthy Heliopsis - Loraine Sunshine plants had many flowers end up with crusty black centers that also resulted in preventing some of the petals from opening up. Otherwise, plants looked good & did not see any particular bug infestation on them.
Would like to find out what it may be and ways to prevent it from happening again next year. I'm in central northern Michigan -zone 4 to 5 range.
Thanks for any help.