There is something the average homeowner might not know about but that we horticulturists have been dealing with for a few years now – the rose rosette virus. As of this moment there is no cure, no real prevention and no rose proven to be immune to it. All this is true no matter what you have heard.
Rose rosette virus is a disease transmitted to your roses by the eriophyid mite. This creature balloons on wind currents and goes surprisingly, long distances. It is a disease that has shown up in all our commonly cultivated roses, according to Dr. Mark Wyndham of University of Tennessee, who is studying the disease. He says this, “All cultivated roses (shrub type, hybrid tea, floribunda, grandiflora and miniature roses) are thought to be susceptible to the disease.” Unfortunately, there is no proof that any species of rose is completely immune to the virus.
By now, I have seen plenty of rose rosette disease. The symptoms I look for include a reddening of foliage that persists through the summer (I look for this once the new spring growth is past because new spring growth is typically red). I look for reddening of stems, flattening of stems and increased thorniness. Often infected plants will present what looks like a witches’ broom. An infected plant will show distortions that are similar to herbicide injury. But if you know that no Round-up or 2,4D, etc. has been used near the plant, then suspect rose rosette virus. Roses infected with rose rosette virus will die within about 3 years after presenting symptoms and if left in the garden pose an immense threat to nearby roses.
The thing to do if you find an infected plant is to immediately “rogue” the plant. This is the fancy way to say REMOVE the plant immediately from your garden or landscape. To rogue a plant, you will essentially dig it up, chop it up, bag it and remove the bag completely from the site. You will want to disinfect your gloves or wear disposable gloves, and completely disinfect whatever tools you used to remove the plant.
When you are at the nursery or garden center looking at roses, inspect for signs of the virus. Don’t buy anything that shows signs of the virus but know that whatever rose you purchase may already have the virus.
All of the above will only slow the spread of this disease. At this point, the outlook for roses is rather dismal. Rose rosette virus is quite serious and is does threaten to wipe out our roses unless a treatment is found. A U.S. government funded grant has been allocated to a 17 member study group to help find a treatment for this terrible disease. Look for research out of Texas A & M University, as Dr. David Byrne will be heading up this group. Also, Dr. Mark Wyndham out of University of Tennessee, Knoxville, is studying the disease with help from the Research Trust of the American Rose Society and Bayer CropScience, LP.