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Evaluation of Inoculation Methods for Inducing Common Smut on Corn Ears. D. D. Pope, Assistant professor, Department of Plant Pathology, University of Georgia, Athens 30602; S. M. McCarter, Professor, Department of Plant Pathology, University of Georgia, Athens 30602. Phytopathology 82:950-955. Accepted for publication 5 June 1992. Copyright 1992 The American Phytopathological Society. DOI: 10.1094/Phyto-82-950.

Tests were conducted in the mountain, piedmont, and coastal plain areas of Georgia to develop a reliable inoculation method for inducing a high incidence and high severity of common smut of corn caused by Ustilago maydis. Inoculum, consisting of six mixed sporidial lines at 10⁶ cells per milliliter, was applied (3 ml per ear) to unwounded silks, to silks wounded by partial or complete removal with pruning shears, or to the exposed ends of ears from which 1.5–2.0 cm of cob was removed with pruning shears, or it was injected through the husk into the cob. Inoculation of unwounded or partially removed silks resulted in little or no disease. Inoculation of the ear tips from which silks were totally removed or where 1.5–2.0 cm of cob was removed was moderately successful. The cob injection and tip injection methods consistently resulted in the highest incidence (as high as 97%) and the highest severity of disease. Certain pairwise combinations of compatible sporidial lines were more effective than others in inducing galls. Ear-injection inoculation methods should be further evaluated for usefulness in producing smutted ears for disease screening and food purposes.