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Evaluation of Ergosterol as an Indicator of Infestation of Barley Seed by Drechslera graminea. T. R. Gordon, Department of Plant Pathology, University of California, Davis 95616; R. K. Webster, Department of Plant Pathology, University of California, Davis 95616. Phytopathology 74:1125-1127. Accepted for publication 26 April 1984. Copyright 1984 The American Phytopathological Society. DOI: 10.1094/Phyto-74-1125.

Twelve seed lots of barley were examined for the presence of Drechslera graminea, the cause of barley stripe. The level of infestation by D. graminea was estimated by each of the following methods: plating seed on barley leaf pieces set on water agar and identifying infested seed by the growth and sporulation of D. graminea; growing plants from seed under greenhouse conditions conducive to disease development and rating plants for the occurrence of barley stripe; and quantifying the concentration of ergosterol extracted from surface-sterilized seed after incubation for 46 hr. Infestation levels as low as 1% could be detected by all three methods. The grow-out method provided the most accurate estimate of the level of infestation by D. graminea but at least 6 wk were required to obtain results. Infestation levels indicated by the seed-plating method correlated well with the grow-out data, and results were available after 7 days. The concentration of ergosterol extractable from a seed sample was porportional to the infestation level indicated by the grow-out data, and the ergosterol assay gave results within 48 hr.

Additional keywords: Hordeum vulgare.