The heredity of resistance to potato leaf roll and mosaic viruses and its relation to yield characters in potato was studied.

Simultaneously the complex infection of Potato virus Y(PVY)and Cucumber mosaic virus(CMV)is also a crucial problem to be resolved at present.

The main species of tobacco virus spread by aphids in Shaanxi included cucumber mosaic virus (CMV), tobacco etch virus (TEV) and potato Y virus (PVY);