An External Ringspot of Potatoes.

This article cites a study that reported on a disease resembling corky ringspot of potato caused by tobacco rattle virus (TRV) in parts of the U.S. in Yorkshire, England. The ringspot symptoms were closely associated with TRV, although varietal reactions did not always correspond. Likewise, varietal reactions did not always correspond with those caused by potato mop top virus. A condition similar to the canker type of internal rust spot was present in some tubers bearing ringspots. In the test reported in this paper, the control cultivar was changed from Pentland Dell to Pentland Ivory because of the susceptibility to tuber blight in the former.