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Importance of Seedborne Tilletia controversa for Infection of Winter Wheat and Its Relationship to International Commerce. W. E. Grey, Research Associate, Department of Plant Pathology, Montana State University, Bozeman 59717. D. E. Mathre, Professor, Department of Plant Pathology, Montana State University, Bozeman 59717; J. A. Hoffmann, Research Plant Pathologist, USDA-ARS, Utah State University, Logan 84322; R. L. Powelson, Emeritus Professor, Department of Botany and Plant Pathology, Oregon State University, Corvallis 97331; and J. A. Fernández, Associate Professor, Division of Plant Science, University of Wyoming, Laramie 82071. Plant Dis. 70:122-125. Accepted for publication 2 July 1985. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1986. DOI: 10.1094/PD-70-122.

Samples of wheat being exported from Pacific Northwest ports in 1983 were examined for the presence of the dwarf bunt fungus, Tilletia controversa. Of 552 samples examined, 141 were free of dwarf bunt. The remaining samples, representing all classes of wheat, contained dwarf bunt teliospores, but none of these seed lots were heavily infested. Field tests were conducted in five states over 2 yr to determine if seedborne teliospores of T. controversa could induce disease. Bunted spikes resulted only when heavily infested seed (≥1 g of teliospores per kilogram of seed) was planted in disease-conducive locations. None of the 552 samples examined in 1983 had dwarf bunt infestation levels ≥1 g of teliospores per kilogram of seed (equivalent to 20,000 teliospores per seed). Therefore, in areas where this disease is not known to occur, there seems to be minimal risk that the importation of grain with low levels of infestation will result in significant development of dwarf bunt.

Keyword(s): Triticum aestivum.