Scottish raspberry leaf curl disease is shown to be etiologically distinct from the analogous American raspberry leaf curl diseases and to be caused by a number of differing viruses which are sap-transmissible from infected raspberry to a variety of plants including weeds and sugar beet. Similar viruses have been isolated from diseased raspberry plants from England, and all caused local lesions and systemic symptoms on Hyoscyamus, Datura, Petunia, French bean and Nicotiana spp. The viruses isolated from raspberry grown in different localities often differed widely. Similar viruses have been isolated from weeds and sugar beet growing near infected raspberries, but none of these has been shown to cause leaf curl.
Both raspberry and sugar beet plants became infected at all times of the growing season, raspberry plants sometimes within 5 weeks of planting. Experiments showed that sugar beet and probably raspberries became infected only when their roots were in contact with soil on which ringspot infected plants had grown. An aerial vector of these ringspot viruses seems improbable and a soil-living vector likely.