Ascochyta blight of chickpea

The disease known as Ascochyta blight is caused by the fungus Ascochyta koolunga. This pathogen is a significant threat to pulse crops, particularly chickpea, in various geographical regions. It is characterized by its ability to survive on crop debris and infected seeds, allowing it to persist in agricultural landscapes across multiple cropping seasons.

Chickpea (Cicer arietinum) is the primary host for this pathogen. The fungus targets all aerial plant parts, including leaves, stems, petioles, and pods. When the infection spreads to the seeds, it significantly compromises seed quality, reduces germination vigor, and serves as a primary source of inoculum for subsequent plantings.

Symptoms typically appear as round or irregular lesions on leaves and stems, often characterized by a light center surrounded by a dark-brown margin. As the disease progresses, small, dark fruiting bodies called pycnidia develop within the lesions. Infected stems may become weakened, leading to lodging, stem breakage, and potentially total plant death in severe cases.

The development of Ascochyta koolunga is highly favored by cool, moist conditions. Periods of frequent rainfall and high humidity are critical for the dispersal of spores via rain splash and wind currents. The pathogen thrives when leaf surfaces remain wet for extended periods, particularly during the flowering and pod-filling stages of chickpea development.

The economic impact of this disease is substantial, often resulting in significant yield losses and poor grain quality. To mitigate the risk, farmers should employ an integrated pest management approach. This includes selecting resistant cultivars, utilizing certified disease-free seeds, implementing at least a three-year crop rotation cycle, and applying appropriate foliar fungicides to protect crops during high-risk weather conditions.