An updated review of Alternaria blight of pigeonpea (Cajanus cajan (L.) Mill sp.)

Pigeonpea (Cajanus cajan (L.) Mill sp.) is an important food legume grown in semi-arid tropical and sub-tropical farming systems under diverse agroecological environments. Alternaria blight (Alternaria tenuissima (Kunze ex Pers.) Wiltshire) is a minor disease when the pigeonpea is sown in June-July but becomes the most serious disease in crops that are sown in mid-September in north-eastern India. Alternaria blight disease has been reported from 13.67 to 49.33% disease intensity in different climatic conditions. This disease is found on leaves, stems, and pods, and dark spots on the leaves and pods reduce the photosynthesis capacity and immature ripening, reducing the amount of quality seeds. The recurrence of the disease depends upon weather conditions, genotypes, age of plants, and virulence of the pathogen, and crop growing areas prioritized the research for developing an extensive range of Alternaria blight. Earlier workers on pathological, physiological, and biochemical characteristics of pathogen the nature of the infection process, and the genetic basis of the pathogen in variability could not clearly be reported. It is required to investigate Alternaria blight including signs, symptoms, biology, status, epidemiology, pathogenic, biochemical, and genetic variability, refinement of the resistance screening techniques, and develop integrated disease management technology of the pathogen to understand the change of disease scenario in the context of climate change. Available information on pathogen symptomatology, status, variability, source of resistance, different management options, and genetic basis of resistance have been updated and discussed with the identification of future research priorities.