Histopathology and isolation of Rhynchosporium secalis from infected barley seed

Rhynchosporium secalis-infected barley seeds collected during 1996 and 1997 were examined. The scald symptoms were distributed over the lemmas, paleas , awns, glumes and rachises, but were more common on glumes and awns. Funga l growth consisting of hyphae and spores was mostly present on the inner su rfaces of lemmas, paleas and glumes in masses surrounded by what appeared t o be mucilaginous material. Hyphae and spores along with mucilaginous mater ial were also observed on the outer surfaces of the awns and rachises. Lemm as and paleas with lesions were incubated for various periods in sterile di stilled water amended with streptomycin and the scald pathogen was successf ully isolated using a streaking method. By this method, number of seeds, le mmas and paleas from which gave rise to scald fungus colonies, did not vary much for different incubation periods. However, as the incubation time was increased, contaminants often overwhelmed the scald colonies. Therefore, e ither no incubation or an incubation period of 12 hr was suitable for isola ting the scald fungus using the streaking method. This appears to be the fi rst report on successful isolation of the scald fungus from infected barley seed.