EN
Three potato cultivars, Adam (early), Rudawa (late) and Skawa (late), were grown in a threeyear experiment in Bałcyny. The severity of late blight and early blight was evaluated using a ninedegree scale during the growing season, as dependent on applied foliar fertilizers: ADOB Mn, Basfoliar 12-4-6 and Solubor DF (applied alone and in combinations). The results, presented as the infection index, were analyzed statistically (STATISTICA ® 8.0 2007–2008). Infection degree was affected by potato cultivar and weather conditions. The highest symptoms of late blight were noted in wet seasons of 2007 and 2009, and the most affected cultivar was Adam. Early blight developed in 2008, characterized by moderate atmospheric precipitation, on late cultivars and on cv. Adam in the last two years. Foliar fertilization had no significant effect on potato infections caused by Phytophthora infestans and Alternaria spp., as confirmed by the average infection index determined for the tested cultivars in each year. The most severe symptoms of late blight were observed in the treatment with ADOB Mn in 2007, and of early blight – in the treatment with ADOB Mn and Solubor DF in 2008. The slightest symptoms of late blight were noted on non-fertilized plants in 2008, and of early blight – on plants fertilized with Basfoliar 12-4-6 in 2007.