Submitted to: Mycopathologia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 1, 2002
Publication Date: May 1, 2002
Citation: Dugan, F.M., Lupien, S.L. 2002. Filamentous fungi quiescent in seeds and culm nodes of weedy and forage grass species endemic to the palouse region of washington and idaho. Mycopathologia. 156:31-40. Interpretive Summary: This research reports on fungi that live inside healthy-appearing seeds and stems of important forage and weedy grasses in the Pacific Northwest. The fungi most commonly found were members of the genus Alternaria. Contrary to most reports, the Alternaria species most prevalent in seeds was not among those responsible for production of mycotoxins. If previous reports of Alternaria in grass or grain seed do not distinguish the toxigenic Alternaria alternata (= A. tenuis) from the much less toxigenic A. infectoria, it is possible that the strains were misidentified. Therefore, persons should be cautious about taking older literature on Alternaria in grass and grains at face value. Other prevalent fungi were identified and several new host-fungus records reported. Several well-known destructive fungi were repeatedly isolated in samples from the field, but not from seed from USDA-ARS germplasm collections.
Technical Abstract: Asymptomatic seeds of forage and weedy grasses from germplasm accessions and from uncultivated sites in eastern Washington and western Idaho were assayed for the presence of quiescent filamentous fungi. Asymptomatic culm nodes of the same species were similarly assayed. The predominant taxa isolated were strains of dematiaceous hyphomycetes, principally strains of Alternaria and Cladosporium. A. infectoria was the species most frequently isolated from seed. A. tenuissima was common and A. alternata was rare. Aspergillus, Penicillium and Fusarium were very rare or absent in stored germplasm. Pathogenic coelomycetes were common in asymptomatic node samples, occasionally present in asymptomatic field seed, but were not detected in germplasm accessions. Reports of frequent occurrence of Alternaria alternata in grass seed should be viewed with skepticism if this species is not distinguished from A. infectoria.