VIEW ARTICLE

Discussion: Fastidious Prokaryotes as Plant Pathogens

Brittle Root of Horseradish in Illinois and the Distribution of Spiroplasma citri in the United States. Jacqueline Fletcher, Department of Plant Pathology, University of Illinois, Urbana 61801; Phytopathology 73:354-357. Accepted for publication 29 July 1982. Copyright 1983 The American Phytopathological Society. DOI: 10.1094/Phyto-73-354.

The known distribution of Spiroplasma citri has been greatly expanded by the finding that this organism is the causal agent of brittle root disease of horseradish in Illinois and Maryland. Prior to the late 1970s, S. citri was known to occur in the United States only in the hot, dry regions of southern California and Arizona, where it causes citrus stubborn disease. One of the vectors of S. citri, Circulifer tenellus, has been collected from Illinois horseradish during most epidemic years. The wide host and geographical ranges of S. citri have prompted a reevaluation of the potential threat of this organism to agriculture in the midwestern U.S. and elsewhere and in crops other than citrus.