Rose Rosette Disease (rose rosette virus)
Rose rosette disease is caused by a virus known as Rose Rosette Virus. It is a devastating disease of roses — particularly since all cultivars are susceptible, including Knock Out roses and wild multiflora roses (Rosa multifora).
Symptoms produced by rose rosette disease are highly variable, depending on the cultivar or species of the rose and the plant’s age. Several different types of symptoms have been reported on infected roses, but some of the more recognizable symptoms of rose rosette disease include “witch’s broom”, excessive thorniness, thickened new canes and abnormal discoloration or excess reddening of new foliage.
Information and photos courtesy LSU AgCenter.