Hi, 

This does not appear to be aster yellows. It looks like the petals were chewed off by any number of insects. Beetles, slugs, snails, grasshoppers, earwigs etc - many different things could have eat the petals. 

They look healthy otherwise. You could leave them still for the pollen and seed heads for beneficial insects and birds. 

If you notice different symptoms, feel free to send in additional photos. 

Emily