Cercospora leaf spot of sesame

The causal agent of Cercospora leaf spot in sesame is the fungus Cercospora sesami. It is a major fungal disease that impacts sesame crops globally, particularly in tropical and subtropical regions where environmental conditions are favorable for fungal proliferation.

The primary symptoms manifest as small, brown-to-reddish, circular or angular spots on the leaves. As the disease develops, these lesions expand and may coalesce, leading to severe chlorosis, necrosis, and premature defoliation of the plant. This loss of foliage significantly reduces the photosynthetic area, which is vital for pod filling and seed maturity.

Disease development is heavily influenced by environmental factors such as high relative humidity, frequent rainfall, and warm temperatures ranging from 25°C to 30°C. The pathogen spreads rapidly through conidia transported by wind and splashing water. Furthermore, the fungus survives between growing seasons in infected crop debris, within the soil, and on contaminated sesame seeds.

The economic impact of this disease is considerable, often leading to reduced seed yield and lower oil content. Severely infected plants are stunted, and their overall vigor is compromised, making them more susceptible to secondary infections or environmental stress. High incidence rates can cause significant financial losses for producers, often requiring systematic intervention.

Managing Cercospora leaf spot requires an integrated approach to disease control. Key strategies include planting certified disease-free seeds, ensuring proper crop rotation to break the pathogen lifecycle, and managing irrigation to minimize leaf wetness. In cases of high disease pressure, the application of appropriate fungicides, such as copper-based formulations or systemic azoles, is recommended to protect the crop during vulnerable growth stages.