Bipolaris leaf spot of millet

Bipolaris leaf spot of millet is a fungal disease caused by the pathogen Bipolaris panici-miliacei. This fungus is a destructive parasite that specifically infects proso millet, leading to significant physiological stress in plants and reducing the overall grain yield and quality.

The primary host for this fungus is common millet (Panicum miliaceum). The pathogen attacks the leaves, stems, leaf sheaths, and panicles of the plant. If the infection reaches the panicle, it may result in discolored or shriveled grains, directly impacting the marketable harvest and seed viability for future seasons.

Symptoms typically manifest as small, brown, or dark-colored lesions that enlarge over time to form elongated spots with necrotic centers. Under high humidity, a dark, velvety layer of conidia and conidiophores becomes visible on the surface of these spots. Severe infection causes extensive leaf chlorosis and premature senescence of the foliage.

Development of the disease is highly dependent on environmental conditions, particularly high humidity, frequent rainfall, and moderate temperatures. The fungus overwinters in infested crop residues remaining in the soil and can also be seed-borne. Wind-blown spores and rain splashes are the primary mechanisms for disease dissemination throughout the field.

Integrated pest management (IPM) is essential for controlling this disease. Key strategies include using fungicide-treated seeds, implementing a sound crop rotation plan (at least 3 years without millet), and conducting deep tillage to bury infected stubble. Foliar fungicides are recommended if environmental conditions favor rapid disease spread during the critical growth stages.

• Use of disease-free, certified seeds.
• Seed treatment with appropriate systemic fungicides.
• Removal of infected crop debris through deep plowing.
• Crop rotation to break the pathogen's life cycle.