OK.
Virginia Cooperative Extension Service - a good source of photos of the symptoms.
- ditto, with a brief list of controls
and so on...
Just about any rose cultivar can harbor the disease. There are online references showing Gloire de Dijon with the disease and Knockout with it. There are online stories of major parts of rose gardens knocked out by the disease. There is no known cure for the disease and only recently has its cause been positively identified as being viral in nature. I understand that rosa multiflora is considered a reservoir for the disease in the wild. It is one wild rose that does not resist the disease. And there are bajillions of multiflora roses in the wild. Furthermore, there is a
suggestion at the ARS rose site that some of these wild multiflora roses were purposefully infected in order to kill the multiflora roses, now considered in many states to be noxious weeds. I understand R. setigera, by contrast, does seem to repel the mites that spread the disease.
What I do not understand is why an uninfected multiflora rose is any more danger to a garden than, say, and uninfected Gloire de Dijon or Knockout rose. The reason that, say, Gloire de Dijon is not a reservoir for the disease in the wilds of Nebraska, Pennsylvania, or Iowa is that it could not survive for one year in the wild. R. multiflora, by contrast can. And it can survive for six or seven years infected with the disease. There are essentially no Gloire de Dijon roses in the wild to serve as reservoirs. This does not mean that Gloire de Dijon is any less of a danger as a host plant to rose rosette disease within a southern garden than is R. multiflora. The reason multiflora is a reservoir is that there are lots of them. And perhaps some of them have been purposefully infected.
I guess cows have a whole different set of pathologies.
