Rose Rosette is a viral disease of roses. It is spread by feeding of the tiny eriophyid mite Phyllocoptes fructiphilus and is very common on Knockout roses. Unfortunately, there are no chemical controls for this type of mite available to consumers.
When a rose shrub contracts Rose Rosette, highly unusual symptoms develop in the plant.
- Stem bunching or clustering, causing a "witches broom" appearance.
- Bright red leaves and stems.
- Leaves are distorted and twisted.
- The stems grow slowly and produce excessive thorns.
Currently there is no known cure for Rose Rosette. If a rose is exhibiting symptoms, the recommended method is to remove and destroy the plant immediately. Other roses can contract it from the infected plant. For more information, visit the American Rose Society (Rose Rosette Disease).