Disease Note.

First Reports of Agropyron Mosaic Virus in Wheat and Mixed Infection with Wheat Streak Mosaic virus in Oklahoma.. J. R. Montana, Department of Plant Pathology, Oklahoma State University, Stillwater 74078-9947. J. L. Jacobs, R. M. Hunger, and J. L. Sherwood, Department of Plant Pathology, Oklahoma State University, Stillwater 74078-9947. Plant Dis. 78:432. Accepted for publication 27 December 1993. Copyright 1994 The American Phytopathological Society. DOI: 10.1094/PD-78-0432D.

In June 1993, a mixed infection of agropyron mosaic virus (AgMV) and wheat streak mosaic virus (WSMV) was identified by direct antigen plating (DAP)-ELISA (AgMV polyclonal antisera provided by D. Seifers, Fort Hays Experiment Station, Kansas State University) in hard red winter wheat (Triticum aestivum L.) in Harper county in northwestern Oklahoma The estimated yield loss in marketable grain was 80-85% in this field. Symptoms similar to those seen in the field were observed when both viruses were transmitted from infected to healthy wheat by mechanical inoculation. Symptoms developed approximately 2 wk after inoculation. The viral isolates were separated by mechanical inoculation to A vena sativa L. as the exclusive host for WSMV, and to Elymus smithii Rydb. Gould, exclusive host for AgMV. Isolate separation was verified by DAP-ELISA. In July 1993, other possible host grasses were collected at random from the periphery of the field. Four of 14 grass samples (E. smithii, Bothriochloa laguroides DC, Aristida sp., and Sorghastrum nutans L. Nash) tested positive for AgMV and Setaria viridus (L.) P. Beauv. tested positive for WSMV by DAP-ELISA. This is the first report of AgMV and the first report of a mixed infection by AgMV and WSMV of wheat in Oklahoma.