June 6, 2006
From: ProMED-mail<promed@promedmail.org>
Source: Science.monstersandcritics.com [edited] <http://science.monstersandcritics.com/news/article_1170406.php/More_than_drought_affecting_wheat_yields>


U.S. agronomists say wheat producers have more than a drought affecting their yields this year [2006], as various viruses invade crops.

Texas Agricultural Experiment Station researcher Tom Allen, a plant disease diagnostician, said he saw more than 150 wheat samples sent to the Great Plains Diagnostic Network lab this growing season, in addition to 400-plus samples the plant pathology staff gathered across the Panhandle.

Ninety-five percent of the samples were diagnosed with the wheat streak mosaic virus. The virus is vectored by the wheat curl mite, Allen said, and so far there's no treatment for either the virus or the mite.

The samples came from as far north as Nebraska and as far south as Dallas, said plant pathologist Charlie Rush, making the outbreak the most widespread in years for wheat streak mosaic damage.

"We don't have a good understanding of the wheat curl mite and its ecology," Rush said. "There are big gaps in our knowledge. But we have things working in the field that should provide answers in the next couple of years."

--
ProMED-mail
<promed@promedmail.org>

[The cereal crop plant wheat, _Triticum aestivum_ L. subsp. _aestivum_, develops symptoms of the disease wheat streak mosaic when infected by wheat streak mosaic virus (genus: _Tritimovirus_, family: _Potyviridae_, WSMV). It can also infect barley, maize, oats and rye and some pasture and weed grasses. The virus is transmitted by the eriophyid wheat curl mite (_Aceria tosichella_). WSMV causes severe disease in some winter wheat crops in the Great Plains of North America, with average losses of 3 percent. There is one report (Argentina, 20040922.2614) from South America. It occurs throughout the Mediterranean Basin at low incidence and is reported from Eastern Europe and Australia.

This report confirms the expected occurrence of WSMV in the Great Plains of North America. The incidence in the 2006 season is stated as being the most widespread in years for wheat streak mosaic damage, making this article noteworthy.

Map:
<http://encarta.msn.com/encnet/features/mapcenter/map.aspx?refid=701512694>

Pictures:
Disease cycle:
<http://ianrpubs.unl.edu/plantdisease/graphics/ec1871-6.gif>
Leaf symptoms:
<http://www2.dpi.qld.gov.au/images/8658.jpg>
Wheat curl mite vector:
<http://www.plantmanagementnetwork.org/pub/php/research/2004/wheat/image/volunteer1sm.jpg>
Links:
<http://www.ext.nodak.edu/extpubs/plantsci/smgrains/pp646w.htm>
<http://www.oznet.k-state.edu/path-ext/factSheets/Wheat/Wheat%20Streak%20Mosaic%20Virus.asp>
- Mod.JAD]

[see also in the archive:
Wheat streak mosaic virus - Australia (WA): 1st Report 20060514.1364
2005
----
Wheat streak mosaic - Australia (NSW) 20051029.3159
2004
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Wheat streak mosaic virus - Argentina: 1st report 20040922.2614
2003
----
Wheat streak mosaic - Australia (12) 20030603.1354
Wheat streak mosaic, first report - Australia (Canberra) 20030417.0941]