Roses can be the most noticeable and beautiful plant in the landscape! There are some issues roses can have though. Rose rosette is a more destructive disease than rose mosaic virus. It is a serious problem in Kansas on wild roses (Rosa multiflora) in pastures and hedges. It is also found in domestic rose plantings. Infection is thought to start with rapid elongation of a new shoot. The rapid shoot growth may continue for several weeks to a length of two to three feet. Following shoot elongation, a witches’ broom or clustering of small branches occurs. The stems develop excessive thorniness and produce small, deformed leaves with a reddish-purple pigmentation. Stems and petioles of Rosa multiflora plants may have reddish blotches or streaks.
Rose plants infected with the rose rosette virus die rapidly, usually within one to two years. Rose rosette is caused by a Emaravirus species. Transmission of the disease has been shown experimentally through grafting and is also thought to be spread by mites.
Though KnockOut roses are resistant to many diseases, they are susceptible to this one. The disease can also be transmitted by pruning shears. Therefore, disinfect the shears when moving from one plant to another by using rubbing alcohol or a disinfectant such as Lysol.
Recommendations: There is no effective control measure for rose rosette-infected plants. In garden settings, infected plants and roots should be removed and destroyed. Do not replant immediately as any infected roots left behind by the infected rose may root graft to the recently planted rose and cause infection.
K-State Research & Extension
Harvey County, Courthouse
PO Box 583, Newton, KS 67114-0583