Etiology of Soybean Severe Stunt and Some Properties of the Causal Virus. T. Weldekidan, Former Graduate Assistant, Delaware Agricultural Experiment Station, Department of Plant and Soil Sciences, College of Agricultural Sciences, University of Delaware, Newark 19711. T. A. Evans, R. B. Carroll, and R. P. Mulrooney. Assistant Professor, Professor, and Extension Plant Pathologist, Delaware Agricultural Experiment Station, Department of Plant and Soil Sciences, College of Agricultural Sciences, University of Delaware, Newark 19711. Plant Dis. 76:747-750. Accepted for publication 11 February 1992. Copyright 1992 The American Phytopathological Society. DOI: 10.1094/PD-76-0747.

Soybean severe stunt, caused by soybean severe stunt virus (SSSV), is a new virus disease affecting Delaware soybeans (Glycine max). Symptoms occur on the first true leaves, and infected plants have shortened internodes resulting in severe stunting, thickened dark green leaves, superficial stem lesions, and reduced number of flowers and pods. Soybean severe stunt occurred in 30 of 50 soybean fields surveyed in Delaware, all in Sussex County, and has not been reported elsewhere. Butanol clarification and differential centrifugation were used to purify SSSV from systemically infected leaves of soybean cv. Essex plants inoculated in the greenhouse, and Essex plants inoculated in the greenhouse with sap or purified preparations of the virus showed typical field symptoms. The isometric, multicomponent virus is approximately 29 nm in diameter and has a longevity in vitro of 12–24 hr, dilution end point of 10^–3, and thermal inactivation of 55 C. The disease is transmitted via soil, and the dagger nematode (Xiphinema americanum) is strongly associated with the occurrence of the disease in the field. Antiserum to 20 isometric plant viruses has failed to react with SSSV.