A nucleic acid vector for concurrently imparting herbicide resistance to a plant and cross protecting the plant. The vector includes sufficient potyvirus nucleic acid sequence to permit viral replication and spread. The vector further includes mutations which attenuate symptoms of viral infection in the plant and which abolish transmission of the virus by an insect vector. The vector further includes an additional nucleic acid sequence encoding a protein which imparts resistance to an herbicide when expressed in the infected plant. Further disclosed is a method of concurrently imparting herbicide resistance to a plant and cross protecting the plant against at least one potyvirus comprising inoculating at least a portion of the plant with the vector. Further disclosed are plant cells treated according to the method and virions derived from the vector.