Brown spot of sugarcane

Cercospora longipes is a fungal phytopathogen classified within the kingdom Fungi, phylum Ascomycota, and genus Cercospora. It is recognized as the causal agent of the brown spot disease in sugarcane. As a major pathogen, it affects the foliage of the crop, negatively impacting the plant's overall photosynthetic capacity and sugar accumulation.

The disease is characterized by the appearance of small, distinct spots on the leaves. These spots typically start as yellowish or reddish flecks that expand into elongated lesions with a dark brown center and a surrounding yellow halo. As the infection progresses, these lesions merge, leading to extensive tissue necrosis, which can result in the premature death of leaves and reduced yields.

The pathogen's life cycle is tied to the survival of the fungus in infected plant debris. During the dormant season, the fungus persists as mycelium and stromata on fallen leaves and stubble. When environmental conditions become favorable, it produces conidia, which are disseminated by wind currents, splashing rain, or contact with agricultural tools and machinery.

Development and spread of Cercospora longipes are strongly favored by high humidity and moderate to warm temperatures, typically ranging from 20°C to 30°C. Prolonged periods of leaf wetness, such as those caused by persistent rain or heavy dew, are essential for successful spore germination and infection. Dense planting, which reduces airflow, further exacerbates the disease incidence.

Integrated pest management strategies for controlling this pathogen include:

• Planting resistant or tolerant sugarcane cultivars as a primary defense.
• Sanitation practices, such as removing or burning crop residues to reduce the inoculum load.
• Maintaining proper spacing to ensure adequate aeration within the canopy.
• The use of preventive or curative fungicide applications when disease thresholds are reached.
• Balancing nutrient management to maintain plant vigor and natural resilience against infections.