Curvularia leaf spot

The disease is caused by the fungus Curvularia senegalensis, a filamentous pathogen that belongs to the hyphomycetes group. It is classified as a necrotrophic pathogen that primarily infects the leaves and stems of host plants. The disease manifests as necrotic lesions that progressively destroy plant tissue, disrupting photosynthesis and overall growth.

Curvularia senegalensis has a wide host range, commonly affecting crops such as sorghum, maize, wheat, and various grasses. While it is more prevalent in tropical and subtropical regions, its impact on cereal crops makes it a significant concern for global agriculture, especially when environmental conditions favor fungal proliferation.

Symptoms of the infection typically appear as small, tan to brown, oval or irregular spots on the leaves. As the infection progresses, these spots expand, coalescing to form larger necrotic areas. In humid conditions, a characteristic olive-black velvet-like growth—consisting of conidia and conidiophores—is often visible on the surface of the lesions.

The development of the fungus is highly dependent on warm, humid environmental conditions. High humidity, frequent rainfall, and temperatures ranging from 25°C to 30°C provide the optimal conditions for spore germination and infection. The fungus is dispersed primarily by wind and water splashing, and it can survive on infected crop residues or within seed tissues.

Management of the disease requires an integrated strategy to minimize crop loss and prevent the buildup of inoculum:

• Using high-quality, fungicide-treated seeds to reduce initial infection levels.
• Implementing crop rotation cycles to decrease the density of soil-borne inoculum.
• Maintaining field hygiene by removing or deep-plowing crop stubble after harvest.
• Applying preventive or curative fungicides, such as triazoles or strobilurins, during the vegetative stages if environmental conditions trigger an outbreak.
• Selecting plant varieties that demonstrate resistance or tolerance to fungal leaf spots.