Helminthosporiosis-inducing fungi associated with black-oat (Avena strigosa Schreb.) seeds.
Fungal isolates of helminthosporiosis-inducing fungi were associated with black-oat seeds [A. nuda] in a survey in several regions of the State of Rio Grande do Sul, Brazil. Observations of morphological aspects identified the following fungal species: Bipolaris sacchari, B. cynodontis [Cochliobolus cynodontis], B. sorokiniana [C. sativus], Drechslera avenaceae [Pyrenophora chaetomioides], D. dematioidea and D. gramineae. Artificially inoculated seeds showed reduced germination. All species were pathogenic to black-oat seedlings with 20-50% mortality. B. sorokiniana was the most aggressive species. Conidia grown on agar media showed lower length than those grown on Typha leaves as substrate. This is the first report of B. cynodontis and B. sacchari associated with Avena sp. seeds.