EN
The aim of the research was to determine the influence of date of protective treatment with fungicides on infection of winter oilseed rape by Sclerotinia sclerotiorum in dependence on weather conditions. Field experiments were carried out in 2004/2005–2008/2009 in Agricultural Experimental Station IPP – NRI in Winna Góra (Western region of Wielkopolska). Two cultivars of oilseed rape – Lisek and Kaszub were examined. Fungicidal protection was performed at three phases of plant development: green bud, yellow bud, full flowering. Significant differences in weight of thousand grains, per cent of infected plants and level of yield were observed in studied cultivars after fungicidal treatment. Fungicides applied in the phase of full flowering were the most effective in reducing of infection by S. sclerotiorum and increasing weight of thousand grains. Seed yield was negatively correlated with average per cent of infected plants. The infection of oilseed rape by S. sclerotiorum was in a high degree dependent on air humidity.