Seed and root inoculations of Agrostis tenuis, Festuca rubra, and Poa pratensis with Bipolaris sorokiniana resulted in increased seed and plant mortality and reduced rate of seed germination, and influenced the development of leaf lesions.  Seed inoculation had a negligible effect on A. tenuis, markedly slowed the germination of P. pratensis, and severely reduced germination of F. rubra.  Inoculation of uninjured roots caused no mortality among any of the grass species; inoculation of injured roots caused some mortality in A. tenuis and severely reduced the stand of P. pratensis, but had no effect on F. rubra.  The incidence of leaf lesions increased on all plants growing in B. sorokiniana-infested soil, but was most severe on root-inoculated plants with injured root systems.

Additional key words: Helminthosporium sorokinianum, H. sativum, injury, epiphytology, leaf lesion.