Switchgrass (Panicum virgatum) can be infected by the rust pathogen (Puccinia novopanici) resulting in lowering biomass yields and quality. Here, two cultivars with divergent rust resistance were used to evaluate the dynamic changes in proteomes following rust inoculation. Label-free quantitative proteomics was conducted on leaf extracts harvested from a susceptible cultivar Summer at 7, 11, and 18 DAI, and leaves collected at 18 DAI from controls and infected plants of the more resistant cultivar Kanlow.