New problems have occurred within the potato mosaic viruses, particularly the potato virus Y complex which is now made up of not only the PVYo (ordinary strain), but also includes the PVYn (tobacco veinal necrosis strain) and the PVYntn (potato tuber necrotic strain) variants. Because of the discovery of new strains of potato mosaic virus, some with the ability to induce tuber necrotic symptoms, and the nearly constant occurrence of recombinants with unknown capabilities, the PVY mosaic complex is slated for research emphasis.
