Q: I would love to know what happened to this poor rose bush I planted last year. It bloomed last year but this year it looks like this. What happened?
A: As glyphosate (Roundup, etc) has become more and more commonly used, more accidents happen. While damage from some herbicides is hard to diagnose, glyphosate damage is classic.
In fact, it looks just like what you see on your rose: tiny leaves clustered along a stem.
I don’t know how your rose was sprayed; it could have been from an unwashed sprayer or just from drift on a windy day.
In any case, my guess is that the rose will die and you’ll get a chance to plant another one.