Rose rosette is a fairly common disease of roses that can cause significant damage. Although more commonly known on weedy multiflora roses, we have received several samples of cultivated roses showing symptoms typical of this disease.
Symptoms of rose rosette can vary greatly but typically include rapid growth of shoots, "witches' brooms" (tufts of branches growing close together), development of tufts of small, deformed, reddish leaves, and excessive thorniness. Affected plants typically decline over time and eventually die within one or two years. The deformation of leaves caused by rose rosette can be similar to the results of herbicide injury.
The cause of rose rosette disease has not been determined. It is suspected to be caused by a virus, and is transmitted from plant to plant by tiny eriophyid mites. We do not know if other insects, such as aphids, may also be able to transmit the disease. Because we do not know the exact cause of rose rosette, it is impossible to confirm a diagnosis of this disease, and diagnoses are based solely on visual symptoms.
Unfortunately, a rose plant with rose rosette cannot be cured. Infected plants should be removed to prevent spread of the disease in the landscape.