FUNGI INFECTING ORNAMENTAL GRASSES AND THE PATHOGENICITY OF Fusarium culmorum (WGSm.) Sacc. AND Fusarium equiseti (Corda) Sacc. TO SELECTED SPECIES

One of the reasons lowering the esthetic appearance of a lawn are diseases caused by fungi. The study on seed material of 11 ornamental grass species was carried out in 2009 and 2010. 681 fungi isolates belonging to 22 species and non-sporulating forms were obtained over the two year study period. Among fungi pathogenic to grasses, species of the genus Fusarium were obtained especially in 2010. In that year, isolates of these fungi constituted 29.94% of all isolated colonies. Colonies of Alternaria alternata were also frequently isolated from the analyzed seed material of the ornamental grasses; in 2009 and 2010 its isolates accounted for respectively 25.36 and 12.57% of all isolates. The study on the health of ornamental grasses conducted in field conditions revealed the occurrence of plants with necrosis of the roots and lower stem internodes. The percentage of such plants ranged from 12% for Coix lacryma-jobi to 69% in the case of Festuca ovina. The mean values of the diseases indices were from 2.6 in the case of Coix lacryma-jobi to 39.6 for Lagurus ovatus and they differed significantly. From the infected plants mainly species of genus Fusarium were obtained. Majority of isolates consisted F. oxysporum and also F. culmorum, F. crookwellense, F. graminearum, F. solani, F. avenaceum, F. sporotrichioides and species Bipolaris sorokiniana and Exserohilum pedicellatunz were obtained. Studies on susceptibility of the seedlings of seven ornamental grass species to infection by Fusarium culmorum No. 34 and F. equiseti No. 62 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 species in the case of F. culmorum and in 5 species in the experimental combination with F. equiseti. Strain Fusarium culmorum No. 34 proved to be the most pathogenic towards Festuca glauca (98.25), and F. equiseti No. 62 towards Phalaris canariensis (89.5).