Urocystis alopecuri is a fungal plant pathogen in the family Urocystidiaceae. Known as 'Foxtail Smut'.
It is found on Alopecurus species; such as Alopecurus aequalis, Alopecurus arundinaceus, Alopecurus geniculatus, Alopecurus myosuroides and Alopecurus pratensis in Europe.