Is this herbicide damage or RRD?
I noticed this ugly growth on one of my pillar roses, A Shropshire Lad, this morning. Last weekend, it was rather breezy and my husband was spraying herbicide on the Creeping Charley so I am hoping it's herbicide damage and not RRD, which I haven't had in my garden yet. The damage, though, seems limited to one cane. On the other hand, not all the growth on that cane looks like this. Higher up on the pillar everything is normal. Nearby roses also look normal.
Thanks for your help.