Epichloe clarkii

Epichloe clarkii is a fungal pathogen responsible for causing a condition commonly known as "choke disease" in various grass species. This fungus belongs to the family Clavicipitaceae and is known for its complex life cycle, which involves a systemic infection of the host plant's tissues, eventually manifesting in the reproductive structures.

The primary hosts of this pathogen include various wild and cultivated grass species, particularly those within the genera Festuca and Agrostis. The fungus acts as a systemic endophyte, colonizing the intercellular spaces of the plant and moving towards the growing points, where it exerts its most significant pathological effects.

The diagnostic symptom of E. clarkii infection is the development of a white to creamy-colored fungal stroma that wraps tightly around the stem below the inflorescence. This physical constriction prevents the proper emergence of the seed head, effectively choking the plant and leading to total reproductive failure of the infected tillers.

The environmental factors critical for the development of this disease include high humidity and moderate temperatures during the grass's flowering phase. The fungus utilizes these conditions to produce spores, which are then disseminated via wind or insect vectors, facilitating the spread of the infection to neighboring healthy plants.

Management of Epichloe clarkii focuses on prevention rather than chemical treatment, as established systemic infections are difficult to eradicate.

• Use of certified, disease-free seed.
• Elimination of infected host grasses in the vicinity.
• Maintaining optimal soil and plant health to minimize stress.
• Regular field scouting to identify and remove symptomatic tillers early.