Arrhenia

Arrhenia (lat. Arrhenia) is a genus of fungi containing several species that act as pathogens on various turfgrasses. These basidiomycetes are known to cause patch-like damage, often being misidentified or associated with environmental stress conditions that lead to severe thinning of the lawn canopy.

The primary hosts of Arrhenia are cool-season grasses, including species of Festuca, Poa, and Agrostis. The pathogen thrives in dense, undisturbed turf environments where moisture persists for extended periods, providing the necessary substrate for the fungus to colonize the leaf blades and crowns.

Symptoms typically manifest as small, circular or irregular discolored patches in the turf. As the infection progresses, the foliage loses its color, turning yellow or light brown, and in high-humidity conditions, a fine, thread-like mycelium may be visible, ultimately leading to the decay of the plant tissues.

The development and spread of the disease are highly dependent on the microclimate. Cool, wet weather conditions facilitate the rapid germination of spores and the spread of mycelium. Poor drainage and lack of sunlight are critical environmental factors that significantly increase the risk of an outbreak in professional and home lawns.

The economic impact of Arrhenia is mainly related to the degradation of turf quality, which is crucial for golf courses and sports fields. Effective management is essential to prevent large-scale turf loss, as recovery from such fungal infections can be slow and requires both cultural and chemical interventions.

• Improve surface and subsurface drainage to reduce humidity.
• Implement regular aeration to promote air circulation.
• Avoid over-fertilization, especially with nitrogen during late autumn.
• Apply preventative fungicides based on professional guidance.
• Manage thatch accumulation to eliminate fungus hiding places.