Increase in wheat streak mosaic virus in North Dakota, USA
Date:09-08-2009
The North Dakota State University [NDSU] Diagnostic Lab and field scouts are reporting an increase in wheat streak mosaic virus (WSMV) this year [2009]. This disease has been reported statewide in winter and spring wheat, plus durum. The levels of severity range from slight to severe.
To reduce the risk of carrying this disease into winter wheat this fall and subsequent spring crops next year, management steps must be taken now to break the green bridge that allows the mites and virus to survive, according to Joel Ransom and Marcia McMullen, NDSU. They say the late harvesting of wheat and corn this year may perpetuate the risk of the mites and virus surviving along the green bridge. It is essential that growers do the best job possible in controlling volunteers and following the winter wheat planting date recommendations.
Research shows the risk of mite dispersal and virus spread tends to follow an oval-shaped pattern extending from the northwest to the southeast according to prevailing winds. If mite populations at the source are high and the mite source is large, the mites and virus will be spread across entire fields. The highest risk for WSMV is planting winter wheat into a field with remaining green wheat volunteers or some grassy weed hosts. Barley and oats, although not commonly thought of as good hosts, also may harbor the disease, so these volunteers also should be controlled.
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