Etiology and Pathogenicity of Fusarium Species Associated with Corm Rot Disease of Gladiolus in Floricultural Production

Abstract

Corm rot disease of gladiolus represents a major constraint in floricultural production, leading to significant losses in corm quality, plant vigor, and flower yield. The present study investigates the etiology and pathogenicity of Fusarium species associated with diseased gladiolus corms collected from commercial cultivation systems. Symptomatic corms exhibited soft rot, vascular discoloration, and extensive tissue decay. Fungal isolates obtained on selective media consistently yielded colonies characteristic of Fusarium, with variation in pigmentation and colony morphology among isolates. Microscopic examination revealed the presence of sickle-shaped macroconidia, septate hyphae, and microconidia typical of Fusarium complexes. Molecular identification using ITS and TEF-1α gene sequencing confirmed the presence of multiple species, predominantly within the Fusarium oxysporum and Fusarium solani species complexes. Phylogenetic analysis demonstrated genetic divergence among isolates, indicating the coexistence of distinct pathogenic lineages in gladiolus production systems. Pathogenicity tests conducted on healthy corms under controlled conditions reproduced typical rot symptoms, fulfilling Koch’s postulates and confirming the pathogenic nature of the isolates. Virulence assays revealed significant differences in aggressiveness among isolates, suggesting strain-dependent disease severity. Disease development was favored by warm temperatures and high soil moisture, which enhanced fungal proliferation and corm infection. The study highlights the complex etiology of gladiolus corm rot involving multiple Fusarium species and underscores the need for integrated disease management strategies. Recommended approaches include the use of pathogen-free planting material, soil disinfection, resistant cultivars, and appropriate fungicidal treatments. Overall, the findings contribute to a better understanding of Fusarium-induced corm rot epidemiology and provide a foundation for developing effective management strategies in floricultural systems.