Rose rosette is a serious rose disease we all have to be on the lookout for. It’s a huge issue in the DFW area. We don’t want it to become so in East Texas, so it’s very important that you learn all you can about it.
The symptoms of this virus disease are quite distinct. The most noticeable sign is a deformed, dense clustered, “witches’ broom” growth habit, often with an abnormal red-orange coloration. The color alone is not totally diagnostic as many roses produce burgundy new growth. The plant basically goes crazy, as if it had been sprayed with a broadleaf herbicide. The stems might also be flattened, enlarged, or elongated, with excessive leaf growth or thorniness. The symptoms of rose rosette might only occur on a single branch or a few shoots at first. The rose may die or may linger stunted for years, spreading to other roses in the area.
Rose rosette virus spreads to other roses in two ways. In gardens it is spread by a tiny eriophyid mite that feeds on an infected live plant and then spreads it to an uninfected plant that it later feeds on. These mites are so small that they can be spread by the wind. To be on the safe side, make sure the roses are spaced so that they do not touch each other. The mite itself doesn’t cause the disease. It only spreads it. The other way of spreading this disease is through plant propagation. Any rose propagated from an infected plant will have the disease as well, as the virus is flowing through its tissue.
There is no cure for rose rosette. Pruning out the noticeably infected branches won’t cure the plant and treating the bush or soil with assorted concoctions won’t cure this disease. By the time you see the symptoms, the disease is being replicated inside the plant with no way for you to rid it. All rose cultivars to date are unfortunately susceptible.
The only option is to completely remove and dispose of the entire infected plant, roots, and all (in a sealed garbage bag), preferably at the first sign of infection. A burn pile is an option in rural areas. If you allow an infected plant to live, you are unfortunately risking the life of all your other roses along with all Tyler and East Texas roses. The disease is in infected living plants only, not the soil, so you can grow roses again in the same area.
If you suspect you have an infected rose, a sample can be sent to the Texas A&M Disease Diagnostic Laboratory. More information and submission forms can be found at plantclinic.tamu.edu. There is a fee for testing rose rosette samples.
Greg Grant is the Smith County horticulturist for the Texas A&M AgriLife Extension Service. He is the author of Texas Fruit and Vegetable Gardening, Heirloom Gardening in the South, and The Rose Rustlers. You can read his “Greg’s Ramblings” blog at arborgate.com and read his “In Greg’s Garden” in each issue of Texas Gardener magazine (texasgardener.com). More science-based lawn and gardening information from the Texas A&M AgriLife Extension Service can be found at aggieturf.tamu.edu and aggie-horticulture.tamu.edu.