Epichloe choke of Elymus

Epichloe elymi is a fungal pathogen belonging to the Clavicipitaceae family, recognized for causing "choke disease" in various grass species. This fungus functions as a systemic endophyte, establishing a long-term symbiotic or parasitic relationship with the host plant throughout its vegetative life cycle.

The primary hosts for this pathogen are grasses belonging to the genus Elymus (wild rye). The fungus resides within the intercellular spaces of the plant tissues, growing alongside the developing shoots without causing significant visible damage until the reproductive phase begins.

The characteristic symptom of Epichloe elymi is the formation of a dense, white-to-yellow fungal stroma that wraps around the developing inflorescence. This physical constraint prevents the emerging head (spike) from exiting the leaf sheath, effectively "choking" the plant and rendering it sterile, which prevents the production of viable seeds.

Development and dissemination of the disease are heavily influenced by environmental factors, particularly cool and humid conditions during the spring growth period. The fungus spreads vertically through infected seeds, where the mycelium remains dormant, and horizontally via wind-dispersed or insect-vectored ascospores that infect healthy neighboring grasses during flowering.

The impact of this disease is most severe in seed production fields where the infection significantly reduces yields and compromises seed quality. Integrated disease management strategies are essential, focusing on the use of pathogen-free seeds, routine monitoring of grass stands, and the destruction of symptomatic plants to prevent the further spread of spores within the field.

• Use of certified endophyte-free seed batches.
• Implementation of spatial isolation for seed-producing plots.
• Regular field scouting to identify and remove infected plants.
• Application of systemic fungicides during the early boot stage of development.