Serologically related strains of potato virus y that are not mutually antagonistic in plants

Tobacco veinal necrosis virus is serologically related to potato viruses Y and C. It does not protect tobacco, Nicotiana glutinosa, or potato plants from infection by them, and tobacco and N. glutinosa plants infected with either virus Y or C are still susceptible to it. There is some evidence that it does not multiply normally in potato plants infected with virus Y and that it is sometimes suppressed in such plants. The possession of antigenic groups in common with viruses Y and C is considered to justify identifying tobacco veinal necrosis virus as a strain of virus Y, and to be of greater taxonomic significance than failure to protect plants against other strains. A further difference from other strains is that it is more virulent towards tobacco than towards potato.