A ribbon-shaped stem (probably formed of multiple stems fusing together) is called fasciation. Branches off a fasciated stem will form abnormal patterns. It is just a birth defect that originated in the growth bud for that stem and not a symptom of Rosette disease.

THANK YOU SO MUCH! Oh, I could just reach through this computer and hug you! I have been so depressed this morning, wondering what fate may come to my precious roses (not just this particular plant).

That makes sense, since it doesn't have the red growth that is usually present in the RRD pictures that I've seen, but it was so odd - I've never seen anything like it before.

Thank you again! You have just made my day!
:)

I'm watching several mass plantings of Knockout and the plants with RRD don't have fasciation.

Thank you for showing the blooms at the end of the cane; when I've had roses with fasciation, they didn't manage a bloom. (When I cut the fasciated cane off, that bush never produced another fasciated cane, FWIW.)

Thank you, Ann.

It didn't look like the RRD pictures I've seen, but I have to admit, I was so very worried. I just don't know how people can live through an outbreak of RRD in their gardens. Just this odd growth was so emotionally draining on me.

I'm so thankful I decided to ask the experts here. I learned something new, and if I ever see fasciation again, I'll recognize it.

We just had another thread on the Antiques forum about fasciation. It's doesn't happen a lot but it's definitely not unheard of or cause for concern about the plant. It's just another kind of genetic mutation like a sport or a vegetative center. And some roses are more prone to those kinds of genetic mishaps than others.

I put a link to the other thread here.

Here is a link that might be useful: Odd cane growth

Thanks. I had not read that thread before. Interesting to think that our strange weather may have something to do with it.