Characterization of Monosporascus cannonballus Causing Vine Decline of Melon in Arid Agricultural Regions

Abstract

Characterization of Monosporascus cannonballus causing vine decline of melon in arid agricultural regions was undertaken to determine pathogen identity, variability, and its association with disease severity under water-limited conditions. Field surveys were conducted in melon-growing areas exhibiting typical symptoms of vine collapse, root necrosis, and sudden plant wilt during fruiting stages. Fungal isolates were obtained from infected root tissues and characterized based on colony morphology, growth rate, and formation of characteristic perithecia and ascospores on culture media. Molecular identification was performed using PCR amplification and sequencing of ITS rDNA regions, confirming the presence of M. cannonballus as the predominant causal agent. Phylogenetic analysis revealed limited but detectable genetic variation among isolates, suggesting a relatively conserved population structure across arid regions. Pathogenicity assays demonstrated significant differences in virulence, with highly aggressive isolates causing rapid root rot, reduced water uptake, and severe vine collapse. Disease expression was strongly influenced by environmental stress, particularly high soil temperature and low moisture conditions typical of arid agroecosystems. The study highlights the interaction between abiotic stress and pathogen activity in accelerating melon vine decline. These findings emphasize the need for integrated disease management strategies, including resistant rootstocks, improved irrigation scheduling, and soil health management to reduce losses caused by M. cannonballus in melon production systems.