The sad part is there is no known cure or preventative yet. I had to dig up and burn my old heirloom white ground cover rose! I am praying it does not spread to my Peggy Martin Rose (left). I propagate and sell that one in my little backyard nursery, Mimi's Greenhouse
The picture at the top of this post is the weird growth habbit that was a dead givaway for me when I saw it on my rose. If you see this growth on any of your roses you probably have it. Rose Rosetta spreads via the wind. A tiny mite no bigger than the end of a pencil lead is the carrier. Please read this PDF by Ann Peck, a renounded Rose Specialist from Tennessee about this disease.
Let's be viligant and not spread this to our other roses or our neighbors plants either. Here in Tennessee we are at a definate disadvantage because of the wild mulit-flora roses that grow in pastures and fallow farm land all around us. If you, like me, cultivated one of those wild roses, it's time to get rid of it! If you can burn it after digging it up do so. If that is not permitted where you live, wrap it in several layers of paper or plastic and dispose of it. Do not bury it or compost it - this will only spread the virus.
Please pass this information on to any of your friends who may be growing roses in their yards and gardens.