Since late 2013, severe infestations of grain sorghum (Sorghum bicolor) by Melanaphis sacchari were observed in several southern states (Arkansas, Louisiana, Mississippi, Oklahoma and Texas) and also more recently in southern Florida, USA. In summer 2015, numerous aphids (>100 individuals per leaf) were seen on plants in 2 grain sorghum trials at Belle Glade, near sugarcane fields and Columbus grass (Sorghum almum). From September to December 2015, a total of 229 symptomatic (exhibiting yellowing of the lower surface of the leaf midvein and necrosis starting from the leaf tip) and asymptomatic stalks of S. bicolor cv. REV RV9782 were collected from these trials and tested for the presence of viruses. The causal pathogen was isolated and identified as Sugarcane yellow leaf virus (SCYLV) based on various molecular analyses. This is thought to be the first report of grain sorghum as a natural host for SCYLV.