One of the reasons lowering the esthetic appearance of a lawn are diseases caused by fungi. Studies were conducted on the sowing material of fifteen turfgrasses belonging to five species. Samples of seeds of the studied cultivars were from the harvest of 2007 and 2008. 573 fungi isolates belonging to 28 species and non-sporulating forms were obtained as a result of the mycological analysis during the two years of the experiment. In each year of studies, the greatest number of colonies belonging to Alternaria alternata. Within the group of pathogenic fungi: Fusarium culmorum, F. avenaceum, F.  equiseti, F. solani, F. crookwellense, F. graminearum F. sporotrichioides, B. sorokiniana, D. siccans and Rhizoctonia solani were obtained. Studies on susceptibility of the seedlings of 8 cultivars of 4 grass species to infection by D. avenae No. 2, D. siccans No. 8 and B. sorokiniana No. 69 were conducted in a growth chamber. The statistical analysis of disease indexes for plants that grew in the experimental combination with artificial infection of the subsoil with above-mentioned strains as compared to the control indicated significant differences in all studied cultivars. Strain D. siccans No. 8 proved to be the most pathogenic towards cultivar Info of perennial ryegrass (92.20), and B. sorokiniana No. 69 towards wood bluegrass Pinokio cultivar (97.75). In the experimental combination with D. avenae the mean values of disease index ranged from 12.25 (Pinia) to 84.00 (Info).

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