Ascochyta blight of chickpea

Ascochyta blight is a devastating fungal disease caused by the pathogen Ascochyta rabiei. This disease poses a significant threat to chickpea production worldwide, capable of causing complete crop failure under conditions that favor rapid fungal development, affecting all above-ground plant parts throughout the growing season.

The fungus is highly host-specific to chickpeas, although it can survive on debris of other related legumes. The primary inoculum sources are infected seeds and diseased crop residues left on the soil surface, which allow the fungus to persist from one season to the next, serving as a reservoir for new infections.

Symptoms appear as circular or oval lesions with a dark margin on leaves, stems, and pods. As the lesions expand, small black fruiting bodies known as pycnidia develop in the centers of the spots, releasing spores. Severe infections result in stem girdling and breakage, causing the entire plant to collapse and preventing grain development.

Environmental conditions play a crucial role in disease epidemiology. High humidity, frequent rainfall, and moderate temperatures ranging from 15°C to 25°C are ideal for spore production and dispersal. Rain splash and wind-blown spores facilitate the rapid spread of the disease across the field, leading to severe outbreaks.

Integrated management is essential for successful control. This includes the use of certified, pathogen-free seeds, planting resistant cultivars, and maintaining a proper crop rotation cycle to break the disease chain. During the growing season, timely application of systemic fungicides is critical, especially when weather forecasts predict extended periods of wet conditions.

• Use of resistant or tolerant chickpea varieties.
• Seed treatment with systemic fungicides.
• Crop rotation with non-host crops.
• Application of foliar fungicides at the onset of symptoms.