LAUSR

Abstract In addition to causing disease in wheat and other grain crops, Fusarium graminearum is associated with a wide range of forage, weedy and non-cultivated gramineous species.. The nature of these associations is often unclear, and interactions between F. graminearum and these hosts are not well characterized, despite their prevalence in and around cereal fields. We observed differences in the host suitability (competency) of spring wheat and six common grasses during three stages of the pathogen life cycle. Pathogen survival in artificially infested stem tissue was comparable between grasses and wheat over two years with the exception of one host. Sexual and asexual spore production on host stems under laboratory conditions varied significantly but exceeded 1 × 105 spores per dry gram of tissue for all grass species. A seedling root infection assay revealed the apparent resistance of two grasses to root rot and indicated that host preference could vary between pathogen isolates. These findings are relevant for how the role of wild grass hosts in disease epidemics of proximate crops and in pathogen evolution is viewed. Managing weedy grasses in field margins and avoiding gramineous pasture–wheat rotations may reduce local sources of F. graminearum inoculum. Changes in the relative pathogenicity of isolates depending on host species suggest that wild grasses could exert selective pressure on F. graminearum and requires further investigation.