Abstract

Potato common scab is a widespread soil-borne disease that severely reduces tuber quality and marketability in major potato-growing regions worldwide. Streptomyces scabies is considered as the key pathogen in alkaline soils of Pakistan. There is a lack of reliable information regarding the incidence of common scab and the scab index in potato-growing areas of Punjab. To address this, a survey was conducted across three major potato-growing districts of Punjab, namely Okara, Sahiwal and Pakpattan to assess disease incidence, severity and established baseline data. A total of 77 representative samples were collected from these three districts and tubers were evaluated using a standardized scab indexing scale. Disease severity varied among the districts. The maximum mean scab index of 58% was found in district Okara, with consistently high severity levels, indicating strong disease pressure under intensive cultivation systems. In Sahiwal, the scab index was 51%. Pakpattan showed a comparatively lower mean scab index of 46%, although localized hotspots with severe disease were also observed, reflecting strong site-specific influences. Genetic resistance variability of the cultivar strongly influenced disease severity, with Mozika and Sante showing high susceptibility, while Lady Rosetta (LR) and Asterix exhibited comparatively lower scab intensity. This study provides the first georeferenced baseline of potato common scab distribution in Punjab and highlights the critical role of cultivar selection in disease management. The baseline data offer a foundation for targeted control strategies and future risk assessment and spatial epidemiological studies of potato common scab in Pakistan.