Downy brome serves as an alternative host for Russian wheat aphid (RWA) in winter wheat. In field studies, downy brome infestations of 5 and 39 plants per m2 increased RWA-infested winter wheat tillers 1.4 to 2.8 times that seen in non-infested plots, respectively. RWA-infested winter wheat tillers were not reduced consistently by fertilization. Chlorpyrifos reduced the number of RWA-infested winter wheat tillers to 15 to 43% of untreated wheat. Insecticide efficacy was not influenced by downy brome infestation or by fertilizer either band- or broadcast-applied.
