Search for Genetically Conditioned Resistance to Rose Rosette Disease Among Garden Roses

Rose rosette disease (RRD) is caused by a negative-sense RNA virus (genus Emaravirus) which is transmitted by the windborne eriophyid mite (Phyllocoptes fructiphilus). This disease is fatal to members of the rose genus and is causing substantial losses of garden roses in the Midwestern to eastern portion of the United States. The few studies that have investigated resistance to RRD have identified a few North American rose species (Rosa setigera, R. palustris, R. carolina) as sources of resistance, but nothing is known about the resistance of garden rose cultivars. A survey was done to collect observational information about which rose cultivars showed or did not show RRD symptom development in regions with high RRD pressure. A total of 564 observations representing about 400 unique cultivars or rose species were obtained. Of these, about 50 garden rose cultivars and 10 species roses showed no RRD symptom development. The other 330 cultivars/rose species showed mild to severe RRD symptoms. The survey made the process of identifying roses resistant to RRD more efficient by eliminating susceptible roses from further evaluation. The next step in breeding for resistance is to develop a series of populations from crosses among RRD resistant species, potentially RRD resistant garden roses, and well-adapted commercial garden roses.