Pathogenicity of Streptomyces scabies and identification of tolerant potato cultivars for scab-prone regions.

Potato (Solanum tuberosum L.) is a crop of global significance, with significant production in Pakistan, Egypt, etc. it is quite vulnerable to Streptomyces scabies, which causes common scab., leading to substantial yield and economic losses. Conventional control methods, including soil pH adjustment and chemical treatments, are often inconsistent and expensive, necessitating the development of resistant cultivars. This study isolated and purified S. scabies from infected tubers using yeast malt extract agar (YMA). The isolates were confirmed as pathogenic through hypersensitivity tests on Nicotiana tabacum. Ten potato cultivars were screened for resistance under greenhouse conditions using soil inoculated with two virulent S. scabies strains (ENC-2 and AQAB-1). Scab incidence and severity were assessed using a standard scab index. The cultivars showed varying susceptibility levels to S. scabies. Cardinal and Sarpomira exhibited the least susceptibility with scab indices of 10.67 and 12.50, respectively, and disease incidences below 60%. In contrast, Bartina and Desiree were highly susceptible, with scab indices of 24.54 and 24.88 and incidences of 86% and 72.72%. Cardinal and Sarpomira demonstrated as potential least susceptible cultivars against common scab, making them suitable for cultivation in scab-prone regions. Further research should focus on breeding resistant cultivars and exploring integrated management strategies to mitigate common scab in diverse potato-growing environments.