The infectibility of various Agropyron species (wheatgrasses) was examined with respect to three isotates of barley yellow dwarf virus (BYDV) by infesting them with appropriate vector aphids, followed by testing by enzyme-linked immunosorbent assay. Feeding behavior of the vetors Rhopalosiphum padi and Sitobion avenae was also electronically monitored to determine their ability to inoculate phloem. The results indicated that resistance to BYDV infection occurs in several Agropyron species. For most species tested. resistance seemed due to failure in virus increase. but in some species a major constraint on infection \\\u27as the inability of vectors to locate phloem. Two potential approaches to breeding for reduced BYDV in wheat by crossing with Agropyron species may thus be: incorporating factors reducing or preventing virus production and incorporating factors reducing the ability of vectors to inoculate plants successfully
