Garden Pests and Diseases: What is wrong with my client's peonies?, 5 by DonnaMack

DonnaMack wrote:
I have a client who has a lot of identical peonies (it's very popular with some people - landscapers install them). Some of them are beautiful and health, and right next to them are horrible looking flowers. I've had thrips and there is some minor damage but this is major. The leaves, by the way, are all healthy.

Can you identify this disease/condition for me? If I know what it is I can find a preventative, because in my experience disease in peonies has to be prevented.

Thank you.