Switchgrass (Panicum virgatum) is a perennial biobased economic crop used for forage, phytoremediation, as an ornamental, and as a model biomass crop with significant cellulosic biofuel potential. In May 2016, mosaic-like leaf patterns of light and dark green areas were observed on a cultivar Purple Breeze switchgrass clone imported into the USDA-APHIS Plant Germplasm Quarantine Programme facilities from the Netherlands. Symptomatic leaf tissue was collected. Based on the results of RNA sequencing and nucleoside sequence comparisons, the causal agent was identified as Barley virus G (BVG; genus Polerovirus; family Luteoviridae). This virus was recently discovered in Korea and has been reported in barley (Hordeum vulgare), foxtail millet (Setaria italica), and proso millet (Panicum miliaceum). This is thought to be the first report of BVG in P. virgatum.