Host Range Profile of Stagonosporopsis citrulli (IIHR-GSB27): The Muskmelon Gummy Stem Blight Pathogen

AbstractGummy stem blight (GSB) is an emerging disease of muskmelon (Cucumis melo L.) in India. This study documents the experimental host range of Stagonosporopsis citrulli isolate IIHR-GSB27. Host range assessment was conducted through detached leaf inoculation on 23 cucurbit crops and collar inoculation on 19 cucurbit crops commonly cultivated in India. Muskmelon and watermelon consistently exhibited very high disease severity in both assays, confirming high aggressiveness of the isolate. Several crops, including summer squash, winter squash, oriental pickling melon, snap melon, long melon and sambar cucumber, showed moderate to high susceptibility. In contrast, pumpkin, bottle gourd and bitter gourd showed low to no disease development in both assays. Correlation analysis showed a strong and significant positive relationship between disease severities recorded in detached leaf and collar inoculation assays, indicating good agreement between the two methods. These findings underscore the epidemiological significance of collateral cucurbit hosts in pathogen survival and spread, highlighting the need to incorporate host range information into crop rotation, cropping sequence and integrated disease management strategies for sustainable control of gummy stem blight in muskmelon-based production systems in India.