Choke disease of brome

Epichloe bromicola is a pathogenic fungus responsible for the systemic disease known as "choke" in various species of brome grass (Bromus). As a member of the Clavicipitaceae family, this fungus functions as a biotrophic endophyte that occupies the intercellular spaces of its host grass throughout its life cycle.

The host range is predominantly limited to brome species. The fungus is highly adapted to these grasses, maintaining a parasitic relationship where it benefits from the host's nutrients while significantly altering its reproductive capability. The infection is often transmitted through infected seeds or via spore dispersal between neighboring plants.

The primary symptom, which gives the disease its common name, is the formation of a conspicuous white to yellowish fungal stroma that wraps tightly around the stem. This "choke" layer effectively traps the developing inflorescence inside the leaf sheath, preventing it from emerging properly and rendering the plant sterile.

Environmental conditions play a crucial role in the manifestation of Epichloe bromicola. High humidity and mild temperatures during the spring season facilitate the emergence of the fungal stroma and the subsequent production of ascospores. These spores are easily disseminated by wind or splashing rain, ensuring the spread of the pathogen within the meadow or seed field.

The economic impact of this disease is significant for forage and seed production industries, as it directly reduces seed yield and can compromise the longevity of perennial grass stands. Management strategies focus on preventive measures, including the selection of pathogen-free seeds, maintaining proper field hygiene, and minimizing the density of susceptible wild host plants in close proximity to cultivated areas.