Gibberella fujikuroi

Systematic position and nature of the pathogen: Gibberella fujikuroi is an ascomycete fungus belonging to the Nectriaceae family. Its asexual stage is identified as Fusarium fujikuroi. It is a significant plant pathogen known for its ability to produce secondary metabolites, including plant growth regulators, which interfere with the host plant's hormonal balance.

Diseases and host crops: The most significant disease attributed to this pathogen is 'bakanae' (foolish seedling disease) in rice, characterized by excessive elongation of stems. Furthermore, it is a key pathogen responsible for ear and stalk rot in maize. These infections pose a severe threat to global cereal production by reducing stand density and overall grain quality.

Biology and life cycle: The pathogen thrives by producing conidia and ascospores, which act as primary inoculum. These spores are disseminated through wind, water, and infected seeds. The fungus overwinters as mycelium or chlamydospores in soil debris or inside dormant seeds, initiating new infections during favorable germination conditions for the host plant.

Conditions for development and harmfulness: The fungus prefers humid conditions with temperatures ranging from 20°C to 30°C. Harmfulness is observed in seedling blight, chlorosis, and the characteristic abnormal elongation of rice plants. In maize, it leads to rotting of the ears and reduced grain yield. Significant economic losses occur when environmental conditions promote rapid fungal colonization.

Protection and control measures: Effective management of Gibberella fujikuroi requires an integrated pest management (IPM) approach:

• Rigorous seed treatment with systemic fungicides to eliminate seed-borne pathogens.
• Selection of resistant or tolerant crop cultivars.
• Implementation of crop rotation programs to break the pathogen's life cycle.
• Proper disposal of crop residues to reduce primary inoculum levels in the soil.