Wheat streak mosaic virus has been confirmed in southern Illinois, says University of Illinois Extension Plant Pathologist Carl Bradley, noting that he has received several reports of similar symptoms in wheat fields across the state.
Symptoms of wheat streak mosaic appear on the leaves as mottling or yellow streaks that run parallel with the veins. General yellowing and stunting may also occur in plants affected by wheat streak mosaic. "This virus is transmitted by the wheat curl mite, and infection likely occurred last fall," says Bradley
Symptoms of wheat streak mosaic could easily be confused with another disease known as bacterial mosaic, caused by the bacterial pathogen Clavibacter michiganense subsp. tessellarius. Bradley says bacterial mosaic has been observed in Illinois in past seasons, but no confirmations of that disease have been reported for 2011.
Bradley reminds producers that the only way virus diseases can be properly diagnosed is by a laboratory that can run specific tests using ELISA (enzyme linked immunosorbent assay) or PCR (polymerase chain reaction). As part of a funded research project, Bradley's laboratory is conducting a wheat virus survey for Illinois. Growers interested in being a part of this survey should send symptomatic leaf samples (approximately 30 leaves) to be included as part of the survey.
Samples must be sent overnight to Bradley's lab immediately after collecting them. Samples should be in a sealed plastic bag, and the county and date of collection must be included along with the contact information of the submitter.
Send samples to: Dr. Carl Bradley, Department of Crop Sciences, University of Illinois, 1102 S. Goodwin Ave., Urbana, IL 61801. Results of any samples submitted will not be available immediately, Bradley says.