Leaf spot diseases in the UK are primarily caused by Dreschelera spp. Leaf spot is a fungal disease, which affects cool season grasses, including perennial ryegrass (Lolium perenne) and brown- top bent (Agrostis capillaris). Leaf spot is most prevalent during warm, humid conditions. The spores are dispersed through rainfall/ irrigation and the extent of the severity of infection will depend upon the virulence of the fungus and the susceptibility of the grass plant. Leaf Spot in the UK must not be confused with Gray Leaf Spot (Pyricularia grisea), a disease which is found on both warm and cool season grasses in the USA.