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Smutting Patterns in Barley and Some Plant Growth Effects Caused by Ustilago hordei. J. V. Groth, Assistant Professor, Department of Plant Pathology, University of Minnesota, St. Paul, MN 55108; C. O. Person, professor, Department of Botany, University of British Columbia, Vancouver, Canada. Phytopathology 68:477-483. Accepted for publication 31 August 1977. Copyright © 1978 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-68-477.

Barley plants (Hordeum vulgare ‘Hannchen’) inoculated with Ustilago hordei were observed to determine the position of smutted and nonsmutted spikes within the plant as well as the effect of inoculation and smutting on plant growth. Distribution of smutted (77%) and healthy (23%) heads on smutted plants was nonrandom according to position. Tillers arising from a single node of the principal culm (tiller families) tended to be either all smutted or all healthy. When families were differentially smutted, older tillers were most frequently nonsmutted. Older families contained one or more smutted tillers less frequently than did younger families. The principal culm, which always was oldest, did not fit this age-frequency pattern; it was frequently smutted. Irrespective of the subsequent occurrence of smut in a plant, inoculation caused reduction of tillering, and changed the pattern of tillering such that inoculated plants produced lateral tillers from nodes higher up on the principal culm.