Cercospora leaf spot of bird's-foot trefoil

Cercospora loti is a fungal pathogen responsible for causing leaf spot disease specifically on species of Lotus, primarily affecting Lotus corniculatus (bird's-foot trefoil). This pathogen is categorized as an imperfect fungus that targets the foliage of host plants during the active growing season.

The primary crop affected is bird's-foot trefoil, an important legume used for forage and fodder. The disease is frequently observed in agricultural settings where moisture levels remain high within the canopy, creating a favorable environment for fungal colonization of the leaves and stems.

Symptoms typically appear as small, angular or circular spots on the leaflets, which often display a dark brown or greyish center surrounded by a darker margin. Under conditions of high relative humidity, a soft, olive-grey mold can be observed on the underside of the leaves, consisting of the pathogen's conidia.

Environmental conditions such as frequent rainfall and temperatures between 20°C and 25°C significantly accelerate the development and spread of Cercospora loti. The fungus survives unfavorable conditions as mycelium or spores on crop debris, which acts as the primary inoculum source for the next growing cycle.

The economic impact of the disease is associated with premature leaf senescence and defoliation, which reduces both the biomass yield and the nutritional quality of the forage. Severe infections can lead to significant economic losses, especially in high-density forage fields intended for hay production.

• Selecting resistant varieties of bird's-foot trefoil.
• Implementing proper crop rotation to break the pathogen's life cycle.
• Removing and burying crop residues to minimize initial inoculum.
• Ensuring optimal plant spacing to promote air circulation.
• Applying preventive or curative fungicides if disease pressure is high.