Investigations on foot rot disease of muskmelon caused by Agroathelia rolfsii – A new record from India

Abstract

A significant disease occurrence of foot rot in muskmelon was observed from February to July 2025 in major muskmelon growing regions of the Chamarajanagar district, Karnataka, India. The incidence of the disease ranged between 5% and 23% as recorded across an area of about 10 ha. Initial symptoms appeared as brown sunken lesions at the infected site, followed by the growth of mycelia, yellowing, and quick wilting of the entire plant. Ten fungal isolates were isolated from the infected plants. These isolates were similar in morphology, with white, fluffy aerial mycelia along with many reddish brown sclerotia after 8–10 days on the PDA medium. The ITS region and TEF-1α were amplified from the genomic DNA of two isolates and sequenced. The BLASTn analysis showed a high sequence similarity with Agroathelia rolfsii sequences available in the GenBank database. The phylogenetic analysis based on ITS and TEF-1α further established the identity of the A. rolfsii isolates. Pathogenicity tests exhibited symptom development between 3 and 4 days after inoculation and the pathogen was subsequently re-isolated and identified, thereby fulfilling Koch's postulates. Based on the cultural, morphological, molecular, phylogenetic, and pathogenicity analyses, the isolated pathogen is identified as A. rolfsii, the etiological agent of foot rot in muskmelon. Based on the available scientific literature and databases, there are currently no reports of A. rolfsii causing foot rot disease in muskmelon in India; thus, this study represents the first documented report of muskmelon foot rot caused by A. rolfsii in India.