Could you supply some pics? That would help a lot in the diagnosis.

Kate

Yes- pictures please.

Knock Out and family are very resistant to black spot. They are susceptible to other diseases and essentially in the same boat with other roses when it comes to attacks from insects and mites.

Would aphids do this? Shortly after I posted my message I took another look and I saw two aphids, but had not seen any before. Meanwhile I'm going to use soapy water. Sorry, I don't know how to post a picture. But I will get some help re: this. Thanks.

Stems would have to be totally encrusted with aphids for a week to cause any noticeable damage to the subsequent flower.

Freezing can cause a pebbly texture to petals, but that's impossible in midsummer.

I would dismantle the buds and look with a magnifier for small critters. This doesn't sound like damage from flower thrips, but maybe so.