Studies on management and variability of Scelrotium rolfsii causing Fruit rot in Sponge gourd

Abstract

Sponge gourd (Luffa aegyptiaca) is an economically important vegetable crop in Asia, especially India, valued for its nutritional young fruits and fibrous mature forms with industrial applications. However, its cultivation could face a significant threat from Sclerotium rolfsii, a soil-borne fungus causing fruit and stem rot. Fruit rot is a newly emerged disease of sponge gourd. It causes considerable yield loss. This study investigated the variability, pathogenicity, and management strategies of S. rolfsii. The variability of S. rolfsii was studied with five different cucurbitaceous hosts. The five isolates showed marked morphological and cultural diversity in colony growth, sclerotia number, size, and shape, with SR1 (Sponge gourd isolate) being the most aggressive and virulent isolate. Molecular identification using ITS-rDNA analysis confirmed all isolates as Athelia rolfsii. Pathogenicity tests revealed sponge gourd as the most susceptible host, especially in its young fruit stage. Cultural studies showed optimal mycelial development at 30°C and pH 6.0, with oat meal agar supporting maximum growth and sclerotia production. Among the tested fungicides, systemic triazoles (Hexaconazole, Propiconazole, Tebuconazole + Trifloxystrobin) exhibited complete inhibition of fungal growth in vitro, while contact fungicides were less effective. Biological control assays identified Trichoderma harzianum (TH3) and Bacillus safensis as the most potent antagonists against S. rolfsii. The findings highlight significant pathogen variability and underscore the potential of integrated management strategies, combining effective fungicides and biological agents, for sustainable sponge gourd cultivation. newline