Rose rosette disease is an increasingly common viral problem in many parts of the United States. This devastating and untreatable disease is caused by rose rosette virus, transmitted by the eriophyid mite Phyllocoptes fructiphilus. The mite becomes a carrier when it feeds on an infected wild or cultivated rose and then is blown by the wind or carried on garden tools, clothes, equipment or a nursery plant to a new location (though they do not fly and will survive off of a plant for less than a day). The primary host for the disease is wild multiflora roses (Rosa multiflora) which are considered invasive plants in much of the United States. The disease can also be transmitted when material from an infected plant comes in contact with or is grafted onto another rose. There is no cure for this disease and plants become weak and susceptible to other problems, including frost damage. The rose typically dies within several years but the easy spread of rose rosette disease makes addressing the problem quickly advisable.

As of 2023, scientific investigation of species and cultivar resistance to rose rosette disease is still in a research phase. Scientists have been able to identify some rose species and cultivars that have moderate to strong resistance to rose rosette disease, but more study is necessary and of particular importance to gardeners who already have the disease present in their garden. Current attention is focused on developing control techniques for the disease as well as understanding the mechanisms by which more-resistant roses deter disease and then genetically reproducing that resistance.

Why is more research necessary if resistant varieties of rose have already been identified? Keep in mind that resistance does not mean that the disease is not present in a plant, just that its symptoms are less likely to be expressed. No roses have been found to be immune to the disease and how and why they resist expressing symptoms is important to know.

Some of the issues that need further research involve particular varieties' methods of resistance and what that indicates about their use in the garden. For instance, if a rose is resistant to the mite that carries the disease, it may possibly still be impacted by the disease if it is present in root material in the growing area. If a plant is affected by the disease but does not express it, it may still be able to transmit the disease to other plants in its growing area if mites are present. Roses that are strongly symptom-free in a particular environment may not be as resilient in all settings. The unknowns are important and likely to take some considerable additional funding, research and trials before all the questions can be answered and the most disease-safe varieties can be developed and reproduced. 

Given that there is still a great deal of uncertainty about the genetic characteristics necessary for a rose to be rose rosette disease "safe", how can a gardener find roses that have been trialed for their own location and are currently the best of what the industry can offer? The American Rose Trials for Sustainability undertakes regional trials and has a list of the most trouble-free roses for each growing area of the United States.  You can read more about what the awards suggest about suitability and disease resistance on their website. Their lists are not specific to rose rosette disease alone and leave the unknowns unanswered. For gardeners without rose rosette disease in their garden and in low-risk areas without multiflora rose nearby, it is a reasonable way to determine suitable roses to introduce to the garden. If you are in a high-pressure area for this disease or it is already present in your garden, for now, proceed with caution and keep a close eye on your new introduction for signs of trouble.

This video interview with several of the leading plant pathologists and rose geneticists working on unlocking the secrets of rose rosette disease and breeding disease resistant varieties is very interesting.

For more information on identifying and preventing rose diseases, see our Guide to Rose Problems.

Courtesy of NYBG Plant Information Service