Gummy stem blight in cucurbits: Pathogen biology, host range and management strategies

Gummy stem blight (GSB) is an emerging and serious disease affecting cucurbitaceous crops. It is caused by three closely related fungal pathogens: Stagonosporopsis cucurbitacearum, S. citruli and S. caricae. GSB has a wide host range among the cucurbitaceous family across the world. About 50-80 % yield losses were reported where the continuous cultivation of cucurbits is undertaken. Symptoms include water-soaked lesions on young leaves, chlorosis, splitting of cortical stem tissues and dark brown discoloration in mature fruits. The pathogen also forms chlamydospores-brown, unicellular and spherical in shape. Molecular techniques involving microsatellite markers and internal transcribed spacer (ITS) regions were used for molecular characterization of Stagonosporopsis spp. Management of GSB is still in a primitive stage; even when integrated methods are followed, they are still ineffective, specifically during rainy seasons. So, development of genetic resistance in the plants can be a good approach for minimal incidence. This review will provide insights on diversity, host range, life cycle and spread of Stagonosporopsis spp.; it also gives an emphasis on development of resistant cultivars. Genomic and molecular approaches (i.e., marker-assisted selection) will be the quick and accurate ways for selection and improvement of resistant lines.