Stagonosporopsis loticola leaf spot

Pathogen and disease type. The disease known as Stagonosporopsis leaf spot is caused by the fungus Stagonosporopsis loticola. This pathogen is a specific parasite that affects leguminous plants, primarily within the Lotus genus. It belongs to a group of fungi that thrive in humid environments, causing necrotic lesions that damage the photosynthetic surface of the host plant.

Affected crops. The primary host for this pathogen is the bird's-foot trefoil (Lotus corniculatus). While it is a robust forage crop, it is susceptible to this fungal infection, especially in areas with frequent rainfall or heavy dew. The disease significantly impacts the yield and quality of forage crops, making it a subject of concern for grassland management.

Symptoms and signs. The disease manifests as irregular, brown or dark-colored spots on the leaves, petioles, and stems. As the infection progresses, these spots may enlarge and coalesce, eventually killing the tissue. A key diagnostic feature is the appearance of tiny, black fruiting bodies called pycnidia on the surface of the necrotic lesions, which release spores to spread the infection.

Development and spread. Stagonosporopsis loticola thrives in conditions of high humidity and moderate temperatures. The spores are typically dispersed by rain splash and wind, facilitating rapid spread across a field. The fungus is known to overwinter in infected plant debris, which serves as the primary reservoir for infection in subsequent growing seasons.

Management and control. Effective disease management relies on integrated agricultural practices rather than intensive chemical use. Key strategies include:

• Crop rotation to break the pathogen's life cycle.
• Ensuring proper soil drainage to reduce humidity levels in the canopy.
• Timely harvesting to remove biomass before the disease spreads to the reproductive organs.
• Selection of resistant or tolerant cultivars suitable for local climate conditions.