A new leaf spot disease of banana cultivar Nendran caused by Alternaria alternata

A foliar disease was observed on banana cultivar Nendran grown in Thalikulam area of Thrissur district, Kerala during the survey conducted in 2017. The symptom appeared as light to dark brown circular, 1.2 to 2.5 × 1.2 to 2 cm sized lesions with concentric zonations on the upper surface of the leaves. Based on the cultural and morphological characters the pathogen isolated from infected leaves was identified as Alternaria alternata. The identity of the pathogen was further confirmed through ITS-rDNAsequencing. The BLASTn analysis of the sequence on NCBI database revealed 99% sequence homology to Alternaria alternata. The pathogenicity of the isolate was confirmed through Koch’s postulates. Thus, the identity of the pathogen associated with the leaf spot on French plantain cultivar Nendran (AAB) was confirmed as Alternaria alternata (Fr.) Keissler.