Not sure how long it will be here...
It looks horrible. I got rid of my Harvest Moon year before last. They are very disease-prone plants. I hope your other plants are ok.
looks like mite damage. If the plant is looking okay... you could try to deal with the mites and wait until next year.
Following instructions i found online for mites.. last year i removed any buds that look clustered/damaged like yours. then in the fall, when the plant dies down, remove all leave litter and mulch/or bedding below the plant... since that is where the mites overwinter.
I did this one some of my plants and this year they are good.. though i have noticed a few clustered buds on my old standard purpureas. (which i didn't clear any mulch last year)
Now the quilled/poor formed flowers is also a part of the big sky line.
I will give that a try...I had cut off some of the damged ones already.
I have a couple of Big Sky, yellow and orange, and they do have those quills. I thought it was supposed to be that way.
It is a defect that is this particular series of plants.