Cochliobolus sativus

Cochliobolus sativus is a destructive fungal pathogen belonging to the Ascomycota phylum. Its anamorphic state, Bipolaris sorokiniana, is globally recognized as the primary cause of common root rot, sub-crown internode rot, and spot blotch in cereals, particularly wheat, barley, and triticale.

The fungus affects various plant organs throughout the entire growing season. Initial symptoms typically appear as browning and necrotic lesions on seedlings and roots. As the disease progresses, it causes characteristic dark brown spots on leaves, sheaths, and heads, leading to premature leaf senescence and overall plant decline.

The biology and lifecycle of Cochliobolus sativus are largely driven by the production of abundant conidia. These spores survive in soil debris, seeds, and on alternative grass hosts. Under favorable conditions—high humidity and warm temperatures (20–30°C)—the conidia germinate and infect the plant tissue, repeating the infection cycle multiple times during the season.

Economic damage caused by this pathogen is significant, as it leads to reduced plant vigor, poor stand establishment, and reduced kernel weight. In severe cases, yield losses can range from 10% to 50%. Moreover, infected grain often exhibits "black point" symptoms, which significantly reduce market grade and seed viability.

Effective management requires an integrated approach to mitigate the inoculum levels. Key strategies include:

• Crop rotation with non-host broadleaf crops;
• Use of disease-free, fungicide-treated seeds;
• Implementation of tillage practices that promote the decomposition of infected crop residue;
• Application of foliar fungicides during the booting and heading stages to protect against secondary spread.