The movement of plant pathogens between cultivated and natural host communities can result in lost agricultural production and altered microbial or plant biodiversity. Fusarium graminearum incidence was studied in wild grass hosts for 3 years to better understand the ecology of this plant pathogen at the interface of crop fields and nonagricultural environments. Research sites (n = 23) were spread between regions of high and low agricultural production and included both agricultural and nonagricultural fields. Pathogen incidence in living grass spikes and senesced, overwintered stems varied between regions of New York and was lowest in a region with sparser agricultural production (P = 0.001). However, pathogen incidence within regions was similar at both agricultural and nonagricultural sites. The groundcover of crop and wild hosts within 1 km of sample sites were equally effective predictors of pathogen incidence, indicating either host group may drive pathogen spread. Rainfall in the 8 weeks preceding sample collection was strongly correlated with F. graminearum incidence in grasses, as well as an increased prevalence of F. graminearum in Fusarium spp. communities (P = 0.001). Grass species diversity was not associated with a reduction in pathogen incidence, and F. graminearum incidence did not vary among the most well-sampled grasses. These results indicate the pathogen colonizes and spreads in noncultivated grasses in a manner consistent with existing concepts of pathogen epidemiology in cereal crops. Increasing host acreage, whether cultivated or not, could drive the colonization of grasses in remote or protected environments, potentially altering their microbial communities.