Powdery Scab of Potato Etiology, its Management through Chemical and Biological Methods

Potato (Solanum tuberosum) production is significantly constrained by powdery scab, caused by Spongospora subterranea f. sp. subterranea (Sss), a soil-borne pathogen that also transmits Potato mop-top virus (PMTV). In Pakistan, particularly in Punjab, the disease has intensified due to the use of susceptible cultivars, limited resistant varieties, and inadequate diagnostic tools, leading to yield losses of 18–22% in severely infested fields. This study investigated the disease etiology and evaluated chemical and biological management strategies under sick-plot conditions at the Institute of Plant Pathology, University of Agriculture, Faisalabad. A Randomized Complete Block Design (RCBD) was used with five treatments: a Trichoderma consortium (T. harzianum, T. viride, T. asperellum), Bacillus subtilis, Pseudomonas spp., Mancozeb, and an untreated control. Treatments were applied through seed-tuber coating and soil drenching. Disease incidence, severity, and plant growth parameters were assessed biweekly and analyzed using ANOVA with Tukey’s HSD (p ≤ 0.05). All treatments significantly reduced disease, with the Trichoderma consortium showing the highest efficacy and simultaneously enhancing plant growth. Mancozeb provided moderate control. The persistence of Sss sporosori and reliance on latently infected seed tubers underscore the ongoing threat of powdery scab in Pakistan. The findings highlight the importance of Integrated Disease Management (IDM), combining biological agents, cultural practices, and selective chemical use. Strengthened resistance breeding and rapid diagnostic tools tailored to regional Sss populations are essential for long-term, sustainable potato production. Keywords: Spongospora subterranea f. sp. subterranea (Sss), Potato mop-top virus (PMTV), Trichoderma consortium and Integrated Disease Management (IDM).