Prevalence and Distribution of Potato Black Scurf (Rhizoctonia Solani Kühn) across Agroclimatic Zones of West Bengal, India

Black scurf of potato caused by Rhizoctonia solani Kühn is one of the most destructive soil-borne diseases affecting potato production worldwide. The disease leads to substantial yield losses and deteriorates tuber quality, thereby reducing market value. An extensive field survey was conducted during two consecutive rabi seasons (2017–18 and 2018–19) in five major potato-growing districts of West Bengal, namely Birbhum, East Bardhaman, Hooghly, Murshidabad, and Nadia, to assess disease prevalence, incidence, and severity at growing stage, harvesting stage, and market level. The results revealed that black scurf disease was prevalent in all surveyed districts, with disease prevalence ranging from 70-100%. The highest disease incidence and severity were recorded in Hooghly district, while comparatively lower disease intensity was observed in Nadia district. The disease was detected across different potato cultivars, with Kufri Pukhraj showing higher susceptibility compared to Kufri Sinduri. Symptomatological observations indicated that R. solani infected both above- and below-ground plant parts, causing stem canker, aerial tuber formation, and formation of black sclerotia on tuber surfaces. The widespread occurrence of black scurf disease across all surveyed areas highlights the importance of adopting eco-friendly disease management strategies, including the use of healthy seed tubers and resistant cultivars. The findings of the present investigation provide baseline information for effective management of potato black scurf disease in West Bengal.