Stemphylium blight

Stemphylium blight is a fungal disease caused by the pathogen Stemphylium sarciniforme. It is recognized as a significant constraint in legume production, particularly affecting crops such as chickpeas and lentils, causing severe foliage damage and reducing overall yields in sensitive varieties across various agricultural regions.

The pathogen is known for its ability to attack all aerial parts of the host plant, including leaves, stems, and seed pods. By causing premature defoliation and tissue necrosis, the fungus significantly disrupts the plant's metabolic processes during the crucial stages of flowering and pod filling, leading to decreased seed size and weight.

Symptoms typically manifest as small, irregular, water-soaked spots that progressively enlarge into brown or grayish-black necrotic lesions. These spots often develop a distinct target-like appearance. Under conditions of high humidity, the lesions become covered with a velvety, olive-brown to black sporulating mass, which acts as the primary inoculum for further spread.

The development of the disease is strictly linked to environmental conditions, specifically prolonged periods of leaf wetness and moderate temperatures ranging from 18°C to 25°C. The fungus survives as mycelia or conidia in crop debris and contaminated seeds, which allows it to persist in the field and initiate new infections as soon as the host crops emerge.

Effective management requires an integrated pest management (IPM) strategy. This includes planting certified pathogen-free seeds, implementing at least a three-year rotation cycle, and ensuring proper soil drainage. The application of foliar fungicides, particularly those containing triazoles or strobilurins, is recommended when environmental conditions are conducive to disease outbreaks to prevent major economic losses.