Emerging Threat of Cucumber Mosaic Virus: A Case Study from Biswanath, Assam, India

Introduction: Cucurbit mosaic disease is one of the most destructive diseases of cucurbits worldwide. Problem: It can cause up to 100 per cent yield loss in severe condition. Aims: The study focused to record the symptomatology, disease incidence and further serological characterization of the virus associated with cucurbit mosaic disease in Biswanath district. Study Design: Round roving survey to record disease incidence, symptomatology and DAS- ELISA for representative samples Place and Duration of Study: Biswanath, Assam, India (2022-2024). Methodology: The study was conducted in five sites of Biswanath district, viz.; Garehagi, Kamalia No. 5, Kamalia No. 4, Pabhoi and Experimental plot, BNCA during September 2023 to November 2024 to identify symptoms, collect cucumber samples for serological diagnosis to assess the incidence of cucurbit mosaic disease through a roving survey across farmers' fields. Leaf samples from different growth stages were tested using DAS-ELISA for presence of cucurbit mosaic virus (CMV). Infection severity was classified as severe (>75 per cent), moderate (>50 per cent), or mild (<50 per cent). Results: Various symptoms were observed; viz., mosaic patterns, leaf roughness, curling, yellowing, mottling, vein clearing, and deformed leaves at both the Kamalia villages and Pabhoi; along with deformed fruits in the experimental plot at Biswanath College of Agriculture. Garehagi showed mosaic patterns, leaf curling, mottling, chlorosis, and deformed leaves. The highest disease incidence of 89.23 per cent was observed at No. 4 Kamalia; followed by 50.84 per cent in Garehagi; 45.13 per cent in the Experimental plot; 43.33 per cent in Pabhoi and 38.09 per cent in No. 5 Kamalia village. Novelty: This is the first extensive survey report from cucurbit growing areas of Biswanath. Conclusion: The widespread occurrence of cucurbit mosaic disease in this region has been a major reason for yield losses, causing a serious threat to farmers' economic and agricultural sustainability.