Ascochyta blight of lentil

Pathogen and disease type
Ascochyta blight of lentil is caused by the fungal pathogen Ascochyta lentis. It is a significant foliar and seed-borne disease that can jeopardize lentil production worldwide. The pathogen remains viable in infected crop debris and seeds, making it a persistent threat that can initiate new outbreaks every season if left unmanaged.

Susceptible crops
The primary host for Ascochyta lentis is the cultivated lentil (Lens culinaris). While some related legume species might harbor the fungus, the commercial lentil crop is the most susceptible and suffers the most substantial economic losses from this specific pathogen during periods of favorable environmental conditions.

Symptoms and signs
Infection begins as small, irregular or circular spots on the leaflets, which later extend to stems and pods. These spots are characterized by a light tan center surrounded by a dark brown margin. The presence of dark, pycnidia arranged in circles within these spots is a diagnostic sign of the disease, which eventually leads to blighting of plant parts and reduced seed fill.

Conditions for development and severity
The disease thrives in cool, wet weather, particularly when frequent rain splashes spores from infected debris onto the lower canopy. High humidity is essential for infection. The damage is severe, resulting not only in reduced total grain yield but also in the degradation of grain quality due to unsightly lesions, which can significantly lower the market value of the harvested produce.

Control and prevention measures

• Use of pathogen-free and fungicide-treated seeds to eliminate primary inoculum.
• Implementation of crop rotation cycles, ideally with a break of at least 3 years before planting lentils again.
• Removal or deep burial of infected stubble to accelerate the decay of the fungus.
• Application of foliar fungicides during the critical stages, especially before rain events and during pod formation.
• Selection and planting of lentil cultivars with demonstrated resistance or tolerance to Ascochyta lentis.