Stagonosporopsis hortensis

Stagonosporopsis hortensis is a fungal plant pathogen belonging to the Ascomycota division. It is widely recognized as the causal agent of stagonosporosis in beans. This fungus primarily affects the aerial parts of leguminous plants, causing significant economic damage by compromising both plant health and seed quality.

The symptoms of infection include distinct necrotic spots on leaves, stems, and pods. On the leaves, these spots often have a greyish center surrounded by a dark margin. Stem infections manifest as deep, elongated lesions that can lead to damping-off in seedlings or structural failure in mature plants. Pod infection directly impacts yield by reducing the number and viability of the seeds.

The biological cycle of the fungus is characterized by its survival in infested crop residues and on seeds. The fungus produces pycnidia that release conidia under favorable moisture conditions. These spores are disseminated by rain splash and wind, facilitating the spread of the disease within the field and to neighboring plants during the growing season.

Optimal conditions for pathogen development include high humidity and temperatures between 18°C and 25°C. Prolonged wet weather significantly enhances the germination and penetration rates of the fungus into plant tissues. Poor air circulation within dense canopy structures further exacerbates the spread of the infection.

To mitigate the impact of this pathogen, integrated pest management strategies are essential:

• Sowing high-quality, disease-free, and treated seeds.
• Practicing strict crop rotation with non-host crops for at least 3 years.
• Removing and destroying infected plant debris after harvest to reduce primary inoculum.
• Application of systemic fungicides during critical growth stages when environmental conditions are conducive to infection.