Gummy stem blight of cucurbits: pathogen biology, disease management, and host resistance

Abstract Gummy stem blight (GSB) is a devastating soil-borne fungal disease that affects a wide range of cucurbit crops, causing significant yield losses in cucumber, melon, and watermelon worldwide. Molecular phylogenetic studies have revealed that the GSB pathogen comprises three closely related species, Stagonosporopsis cucurbitacearum , S. citrulli , and S. caricae . These species share indistinguishable morphology and host range but differ in geographic distribution. The combined application of resistant cultivars, optimized agronomic practices, eco-friendly biocontrol agents, and chemical fungicides is the most effective strategy for integrated management of GSB in practice. Quantitative trait loci and genes associated with GSB resistance have been identified in cucurbits, and some have been used in breeding programs to improve GSB resistance. This review summarizes recent advances in Stagonosporopsis taxonomy, disease cycle and epidemics, cucurbit- Stagonosporopsis interactions, resistance mechanisms, and integrated strategies for disease management. It also outlines future research directions, including elucidation of pathogenicity mechanisms in Stagonosporopsis , genome-informed disease diagnostics, enhancement of cucurbit resistance through breeding, and development of climate-smart, sustainable integrated management systems for GSB in cucurbit crops.