Symptom: Witches Broom. Witches broom is a dense mass of shoots growing from a single point, with the resulting structure resembling a broom or a birds nest.
Symptom: Excessive Thorns. In normal roses, thorns are spaced along the stem. Rose plants infected with Rose Rosette Disease exhibit excessive thorns, clustered closely together; sometimes on just one or two shoots.
Symptom: Excessive Lateral Shoots. Abnormal growth such as excessive lateral shoots is another symptom of Rose Rosette Disease. This growth is often thin, weak and spindly; it may feel rubbery and bend without breaking.
Symptom: Malformed Leaves. Roses suffering from Rose Rosette Disease will have leaves that don't completely open or are stunted. Red coloration of leaves is normal in the spring, but not at other times of the year.
Symptom: Red Stems and Leaves. While red stems and leaves are a symptom of Rose Rosette Disease, do not confuse this with the red stems and leaves on new growth.
Symptom: Rapid Stem Elongation: Rapid stem elongation is a symptom of Rose Rosette Disease, but this often occurs with new growth or with hard pruning as well. Look for other symptoms to support a diagnosis of Rose Rosette Disease.
Symptom: Malformed Buds: Malformed buds will often grow in clusters, may remain closed, or appear an off color, often lacking pigment.
Just because you see a symptom that may appear to be Rose Rosette Disease, it doesn't always mean that your plant is infected. Some of the symptoms may be caused by other factors. For instance, insects such as thrips or spider mites may cause malformed buds and deformed leaves. Products containing glysophates and other herbicides may produce symptoms that mimic Rose Rosette Disease.
Experts agree that it's best to look for multiple symptoms before diagnosing Rose Rosette Disease.
The virus lives and multiplies in the Eriophyid mite, which then carries the virus to the rose plant. The virus becomes systemic within the plant, and then disrupts the DNA of new growth. Research has shown that plants can become infected with the virus but not show symptoms as much as 18 months after infection. During this incubation period, the infected, asymptomatic plants can transmit the disease to other roses via the mites. This new information is discouraging because it makes managing the spread of the disease very difficult. It also helps to explain why the disease has become so pervasive in Collin County.
So what do you do if you are convinced that your plant is infected? The infected plant(s) must be removed, including the roots. Removal helps prevent the spread of Rose Rosette Disease. There is no known cure for infected plants and there are no known resistant varieties of roses. Removing symptomatic stems will not cure the plant and there is no available product to kill or control the virus.