Downy mildew of chickpea

Downy mildew of chickpea is a significant fungal disease caused by the oomycete Peronospora ciceris. This pathogen is known for its ability to rapidly compromise the health of chickpea crops, particularly in regions where environmental conditions favor the development of oomycetes.

The primary host for this disease is the chickpea plant (Cicer arietinum). Given its host specificity, Peronospora ciceris cycles primarily within fields sown with chickpea, utilizing the host tissue to complete its reproductive cycle during the growing season.

Symptoms typically begin with the appearance of pale green or yellow chlorotic lesions on the adaxial leaf surface. In humid conditions, a characteristic greyish to violet mycelial growth appears on the abaxial side of the leaves, indicating the production of spores. Eventually, the infected leaf tissues become necrotic and wither away.

The progression and spread of this disease are driven by specific environmental factors, most notably cool temperatures (15–20°C) combined with high humidity. Rainfall and dew are critical, as they provide the necessary water for the motility of zoospores and facilitate the spread of the pathogen from infected leaves to healthy foliage.

The economic impact of downy mildew is significant, leading to defoliation, which hampers the plant's ability to produce robust pods and high-quality seeds. To manage this disease, farmers should employ strategies such as crop rotation, selecting resistant or tolerant varieties, managing plant debris, and utilizing appropriate fungicide programs when infection risk is high.