Until recently, triticale was considered to be a species of low disease susceptibility. Research results indicate, however, that it is more and more frequently infected by stem-base, leaf, and spike diseases, and the loses caused by disease occurrence may reach 1/3 of yield. The aim of the study was the determination of leaf and spike disease occurrence in winter triticale protected with fungicides, in the conditions of diversified nitrogen fertilization doses. Study material was winter triticale plants cultivar Gniewko, obtained from a three-year-long (2009-2011) filed experiment at the Production and Experimental Station in Bałcyny near Ostróda. First factor was nitrogen fertilization: 30, 60, 90, 120, and 150 kg·ha^-1. Second factor was the level of protection against fungal diseases: seed dressing, seed dressing and one on-leaf treatment, and seed dressing and two on-leaf treatments. Weather conditions in the study years significantly differentiated the intensity of disease symptoms. Nitrogen fertilization significantly affected winter triticale wholesomeness and caused a decrease in flag leaf infection by Rhynchosporium secalis only in the second research year. However, in the case of chaff septoriosis, an increase in infection was noted under the effect of increasing nitrogen doses. The applied fungicides effectively inhibited the development of flag and sub-flag leaves (leaf septoriosis, brown rust, powdery mildew) and spikes (chaff septoriosis and powdery mildew). Significant inhibition in fungal disease intensity was noted only after the application of two on-leaf treatments.

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