Choke

Choke (Epichloe typhina) is an endophytic and pathogenic fungus in the family Clavicipitaceae, phylum Ascomycota, that colonises the tissues of various cool-season grasses (Poaceae) across Europe and North America. The name refers to the disease it causes — infected grass tillers are typically 'choked' (prevented from flowering) when the fungus produces a dense, white to cream-coloured, stromata (a compact fungal structure) that surrounds the flowering stem before it can emerge, suppressing seed production. Epichloe species exist along a mutualism-parasitism continuum; some strains are biotrophic endophytes living almost entirely within grass tissues without obvious symptoms and conferring benefits to the host such as increased drought resistance and deterrence of herbivores through alkaloid production, while others — including E. typhina — are more parasitic in nature, sterilising infected host tillers. The fungus spreads via airborne ascospores produced on its stroma that infect new host plants. Related Epichloe/Neotyphodium endophytes are of great practical importance to agriculture as they produce ergot alkaloids and other compounds that can cause toxicosis in livestock grazing infected pasture grasses. As a fungal pathogen/endophyte rather than a wildlife species, it is Not Evaluated by the IUCN.