Ecological consequences of pathogen accumulation on an invasive grass

Abstract

Release from natural enemies can contribute to the success of biological invasions. However, the advantage gained through enemy release may diminish over time as pathogens, parasites, or herbivores accumulate on invasive species. Pathogen accumulation may result from the development of novel host-pathogen interactions in the invasive range or the introduction of pathogens from the invader's home range or other areas. Previous studies suggest that pathogen accumulation may reduce the performance of invasive species but experimental demonstrations are lacking. Microstegium vimineum is a highly invasive annual grass with an expanding distribution in eastern North America. Bipolaris species and other fungal pathogens have recently been shown to cause foliar blight on invasive populations of Microstegium. Here we used experimental inoculations in controlled laboratory and greenhouse conditions and fungicide applications in the field to evaluate host relations of pathogens infecting invasive Microstegium and th...