Turnip Mosaic Virus in the Illinois Horseradish Germ Plasm Collection. D. K. Horwitz, Research Assistant, Department of Horticulture, University of Illinois, Urbana 61801. Jacqueline Fletcher, Assistant Professor, Department of Plant Pathology, Oklahoma State University, Stillwater 74078; and Cleora J. D’Arcy, Associate Professor, Department of Plant Pathology, and A. M. Rhodes, Professor Emeritus, Department of Horticulture, University of Illinois, Urbana 61801. Plant Dis. 69:246-248. Accepted for publication 14 September 1984. Copyright 1985 The American Phytopathological Society. DOI: 10.1094/PD-69-246.

In fall 1982, turnip mosaic virus (TuMV) was detected by enzyme-linked immunosorbent assay (ELISA) in 92% (136/148) of the horseradish clones in the Illinois germ plasm collection. Sap extraction from mature symptomatic leaves was more sensitive than leaf disks for detecting TuMV by ELISA. TuMV was detected by symptomatology and by ELISA in the highest percentage of clones during cool spring or fall weather. No horseradish clone remained both symptomless and negative by ELISA throughout the 2 yr of this study.