In both ecology and medicine, we often focus our efforts on understanding the interactions between a single pathogen species and a single host species. While this simplification can be extremely useful for some questions, pathogens and their hosts often interact within a complex community of hosts, vectors, and multiple pathogenic species. In addition, host nutrition can determine the success of infection and co-infection and also can determine the disease resulting from infection. Plants can serve as a model system for studying this: they provide a unique opportunity to experimentally tease apart these multiple varying factors. I will present findings from experimental work in the field and lab to tease apart the relative importance of regional and local context, host nutrition, and host traits in determining infection and co-infection by insect-vectored viruses in grass hosts.