RRD (Rose rosette disease) is not transferrable to clematis so no worries there. Without a close-up photo to convince me otherwise, that looks like just the very active new growth of an otherwise quite robust and healthy clematis vine. I think you may be worrying unnecessarily.

Did you fertilize this spring and if so, with what?

I have two clematis growing on this cattle panel, one is already blooming, but this is later. I have never fertilized either of them.

The one shown grew up into a nearby apple tree and almost blocked the gate into the chicken yards last year.

I hope you are right; time will tell. If it blooms a normal bloom I will assume it is just because we have been getting abnormal amounts of rain....almost daily. It may be Polish Spirit.

Glad to hear nothing else gets RRD. I have lost quite a few roses to that disease.

Thanks for your reply.

Wow! I wish mine were that robust! And you say you never have fertilized them?! Wow!

How did you get such lush growth? Mine struggle along even with organics and fertilizing! :)

I agree that it is just lush new growth and the extra rain could be the cause.