tuber (Solanum tuberosum) yield quality and resistance against Streptomyces scabies; the bacterial effect was attributed to reduced soil pH. So far, no information has been available about the influence of S, Mg and supply of micronutrients on bacterial and fungal diseases of potato plants. Field trials performed in a split-plot design with varied fertilization treatments (NPK with/without S and Mg and microelements B, Zn, Mn, Cu fertilization) including three potato cultivars were conducted in the south eastern region (near Zamość) of Poland in 2004-2006. The application of S and Mg and micronutrients decreased the tuber infection rate and severity of Streptomyces scabies and Rhizoctonia solani, while increasing potato tuber yield. Generally, tuber yield and wholesomeness were mostly related to a genotype (cultivar), mineral fertilization treatments and their interaction with a cultivar.