I guess you've never heard of Aster Yellows virus. I'd bet money that this is the problem with your plants. Control is very easy...pull up all of the plants and dispose of them. Do not plant them again.

I've heard of it, all right, but not seen it. I did some on-line research after your post, and I'm not sold on CD having that. Every site I read mentions a few other symptoms, such as yellowing leaves with green veins, reddish colored leaves, twisted petals - the normal blooming flowers DO have twisted petals, but they are supposed to in this variety, tiny twisted leaf-like clusters coming out of the flowers,stunted growth, among other things. My plant has none of these, just healthy looking centers with no petals on some of the flower heads.

I'm sixty this year and have seen a lot of weird things through my years of gardening. One year, I bought some echinacea seeds on ebay that were opened pollinated varieties of the some of the early-newer varieties being introduced. Art's Pride was one, and there were others that I never see mentioned or sold anymore. A friend who has a green house started them for me and gave back the seedlings, which I potted up. When they bloomed, there were some really odd looking flowers. I had some with centers and no petals, some with tightly quilled petals that never opened up - I know, they sell one like this now!, and some with teeny tiny petals around a large center. I figured that the genetics of these echies were causing the different looking flowers. The brother of another gardening friend took them and has been growing them now. I've not talked to him in a while, and I wonder if he is still growing them. Anyway, this is the first time I've seen a healthy looking Shasta Daisy put out normal flowers and flowers with normal looking centers with no petals. I guess I was wondering if there could be a genetic issue here too. If it is indeed Aster Yellows, I'd like to be sure, and I'd then destroy the plant. I have no problem doing that.

My painted daisy is doing this. But when I purchased the plant, the blooms were beautiful. Nothing else in this garden has suffered.