Ventenata dubia (African wiregrass), a winter annual weed, is a non-native species invading grasslands, rangelands and pastures throughout the USA. Limited information is available on its suitability as a host to pathogens and insects in its invaded range. The barley/cereal yellow dwarf virus (B/CYDV) complex occurs ubiquitously in Poaceae species. In non-managed grasslands, BYDV infection influences competitive dynamics between native and invasive grasses and facilitates invasion by non-native annual weeds. The Palouse prairie of south-eastern Washington and northern Idaho, USA, is an endangered ecosystem. Surveys of V. dubia in Palouse prairie and neighbouring Conservation Reserve Program (CRP) habitats were conducted to determine whether B/CYDV viral species are present. Laboratory tests examined the suitability of V. dubia to host BYDV-PAV and serve as an inoculum source. Plant growth and weight parameters were measured to gauge the impact of BYDV-PAV on V. dubia. Infection of V. dubia in Palouse prairie and CRP habitats with two species of BYDV, PAV and SGV, was detected for the first time. The ability of BYDV-PAV to infect V. dubia in the laboratory and transmission from infected V. dubia to barley were demonstrated. BYDV-PAV-infected V. dubia showed reductions in plant height, number of leaves and tillers per plant, and above-ground dry weight, suggesting that V. dubia is sensitive to BYDV. Results demonstrate that V. dubia is a host to BYDV and may serve as a virus inoculum source with potential implications for its management, competitive dynamics between invasive and native grasses and future conservation of endangered grasslands.