METHOD: Both ELISA and Visual Examination CONDITIONS: Green House - 18-22C with light intensity of 3-5Klux METHOD NARR: A large number of accessions were tested by mechanical inoculation with PVY n,o,and c. These preliminary rescreening of accessions that appeared to be resistant to the virus including top-graft inoculation via infected Nicotiana. In all cases virus titre was verified by ELISA and in some cases by tobacco-bioassay and dot-immunobined as diagnostic hosts were tested for susceptibility to PVA, PVM, PVS, and PVX. RESULTS NARR: Two accessions of sto were found to be immune to PVYn. Chc 472819 can be used to identify PVYn and PVYo strains. AUTHOR EXPLANATions useful as indicator plants and the particular symptoms they differed by, were presented.