Sometimes the best way to learn about a new plant disease is to see it for the first time in person. While passing a neighbor's rose, I noticed it had the most irregular tip growth imaginable. The unusually reddish leaves were dense, fine and the growth reminded me of a stunted witch's broom (a physiological abnormality caused by various diseases). I took a couple of photos of the strange shoots and leaves, took them home and quickly identified the problem via a basic Google search--Rose Rosette Disease (RRD).

There's a reason I didn't recognize it right away. This disease, which is thought to be caused by a virus spread by eriophyid mites, has only recently been troublesome to cultivated roses. It was originally found in 1940 on the invasive multiflora rose (Rosa multiflora), and to this species it is deadly. Data supports it is equally as deadly to garden roses--and Knock Out® roses have been shown to be particularly susceptible. As with most plant viral diseases, there is no cure for RRD.

There are lots of roses in my garden, so I'm hoping the disease won't come my way, but anything vectored by insects can't be contained forever. I wonder how much time I have?

Virginia Tech has a great write up on RRD. Give it a read.