Possible Rose Rosette Disease – Request for Diagnosis - Ask Extension
I have a mature rose bush that has recently developed unusual growth. Some sections have very red, distorted and curled leaves, along with stems that ...
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Possible Rose Rosette Disease – Request for Diagnosis #945800
Asked September 24, 2026, 3:24 PM EDT
I have a mature rose bush that has recently developed unusual growth. Some sections have very red, distorted and curled leaves, along with stems that appear to have an unusually high number of small thorns/prickles. Other parts of the same plant still look healthy and are flowering normally.
A plant identification app suggested Rose Rosette Disease (RRD), but before removing the rose, I would really appreciate an expert opinion. Could this be RRD, or could it be normal new growth, herbicide injury, mites, or another problem?
I’ve attached close-up photos of the affected growth
Thank you very much for your help.
Montgomery County Maryland
Expert Response
The growths pictured don't have clear indications of Rose Rosette Disease yet, which can be subtle until the infection is more advanced. My overall impression from the images is that the odd growths are a bit suspect but not blatantly RRD.
Red young growth by itself isn't a reliable symptom, as leaf pigmentation is influenced by several factors, including tissue age and weather conditions. Distorted leaves can be caused by pesticide exposure (such as herbicide drift, if anything was applied in your yard or close by), a different virus, or the feeding of certain mites (not necessarily those transmitting RRD). Excessive thorniness is a trait of RRD, but isn't always prominent, and might be triggered by genetic mutations or infection by another type of virus. When symptoms like these overlap and begin on isolated parts of the plant (not more uniformly distributed on several branches), that lends more weight to RRD being suspect, but it's still not conclusive.
Only a virus lab test would potentially confirm RRD (even then, a false negative is possible). Testing could be expensive (at least compared to the typical cost of a replacement rose), and not all plant diagnostic labs carry the testing materials for every plant virus.
For now, all that can be done is to monitor the plant for more distinctive or severe symptoms, or you can decide to replace it out of caution. Since there's no treatment for RRD and no feasible way to keep the mites contained or suppressed, there's unfortunately little recourse aside from waiting longer or disposing of the plant. Due to the lateness of the season, the plant probably won't produce much new growth at this point, which may delay narrowing-down the diagnosis until spring growth resumes.
Miri
Red young growth by itself isn't a reliable symptom, as leaf pigmentation is influenced by several factors, including tissue age and weather conditions. Distorted leaves can be caused by pesticide exposure (such as herbicide drift, if anything was applied in your yard or close by), a different virus, or the feeding of certain mites (not necessarily those transmitting RRD). Excessive thorniness is a trait of RRD, but isn't always prominent, and might be triggered by genetic mutations or infection by another type of virus. When symptoms like these overlap and begin on isolated parts of the plant (not more uniformly distributed on several branches), that lends more weight to RRD being suspect, but it's still not conclusive.
Only a virus lab test would potentially confirm RRD (even then, a false negative is possible). Testing could be expensive (at least compared to the typical cost of a replacement rose), and not all plant diagnostic labs carry the testing materials for every plant virus.
For now, all that can be done is to monitor the plant for more distinctive or severe symptoms, or you can decide to replace it out of caution. Since there's no treatment for RRD and no feasible way to keep the mites contained or suppressed, there's unfortunately little recourse aside from waiting longer or disposing of the plant. Due to the lateness of the season, the plant probably won't produce much new growth at this point, which may delay narrowing-down the diagnosis until spring growth resumes.
Miri
