Didymella rabiei

Didymella rabiei (Chickpea ascochyta blight fungus)

Didymella rabiei is a fungus responsible for causing Ascochyta blight in chickpeas (Cicer arietinum). This disease is a significant concern for chickpea producers worldwide, as it can lead to considerable yield losses. The fungus infects the stems, leaves, and pods of chickpea plants, leading to lesions, wilting, and sometimes the death of the plant. Effective management of Didymella rabiei involves an integrated approach, including the use of resistant cultivars, crop rotation, and fungicides.

Description

Didymella rabiei is characterized by its ability to produce pycnidia and pseudothecia on infected plant tissues. Pycnidia are asexual fruiting bodies that release conidia, which are asexual spores that can spread the disease under wet conditions. Pseudothecia, the sexual fruiting bodies, release ascospores that contribute to the disease's spread during cooler and moist periods. The lifecycle of Didymella rabiei includes both asexual and sexual reproduction, allowing it to survive and proliferate under a variety of environmental conditions.

Symptoms and Impact

The initial symptoms of Ascochyta blight caused by Didymella rabiei include small, dark lesions on the leaves, stems, and pods of chickpea plants. As the disease progresses, these lesions can expand and coalesce, leading to significant tissue damage. Infected pods may contain discolored or shriveled seeds, reducing the quality and quantity of the harvest. In severe cases, the disease can cause plant death, leading to total crop loss in heavily infected fields.

Management

Management of Didymella rabiei and Ascochyta blight in chickpeas involves several strategies. The use of resistant chickpea cultivars is one of the most effective means of controlling the disease. Crop rotation with non-host crops can help reduce the inoculum in the soil. Timely application of fungicides can also be effective, especially when applied at the first sign of disease and before heavy rainfalls, which can facilitate the spread of spores. Clean seed practices and the removal of infected plant debris from the field can further help in managing the disease.

Economic Importance

Didymella rabiei poses a significant threat to the global chickpea industry. Chickpeas are a crucial source of protein, especially in many developing countries where animal protein is scarce or expensive. The disease can cause substantial economic losses due to reduced yield and quality of the harvested chickpeas. Managing Ascochyta blight is therefore critical not only for the economic viability of chickpea production but also for food security in many parts of the world.

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