ISSUE 2 May 20, 2010
North Central ND
We have continued to see fields of winter wheat and spring wheat volunteers with wheat streak mosaic virus. The recent warm weather has the potential to exacerbate the situation. Mite reproduction is at its peak when temperatures are in the 70ís with a complete life cycle occurring in as little as seven days. Iíve had several questions from producers about what crop to follow up with in infected fields. Avoid winter and spring wheat, durum, corn, barley, oats, and rye as these can be hosts for the wheat curl mite that transmits the virus. Green foxtail and barnyard grass can also be hosts for the mite and virus, so control of these weeds is important. Sunflower, canola, soybeans, pulse crops, and flax are not hosts and are good options depending on cropping history in a particular field. In addition to wheat streak mosaic virus, tan spot has begun showing up in winter wheat fields in the days following the last system of wet weather. Wheat on wheat fields are particularly at risk for this fungal disease. Numerous systemic fungicides effectively control this disease. Please refer to the field crop fungicide guide (http://www.ag.ndsu.edu/extplantpath/fungicide.html) for specific information.
We have begun catching flea beetles in canola fields at the North Central Research and Extension Center and in northeastern McKenzie County. Some of the Canadian canola growers are experiencing a shift from the predominate crucifer flea beetle to increasing proportions of the striped flea beetle, which has historically been a minority species. Canadian researchers believe this shift is occurring because the striped flea beetle is not controlled as well as the crucifer flea beetle by insecticide seed treatments. A study is currently underway to determine if this species shift is occurring in canola growing areas of North Dakota.
Crop Protection Specialist
North Central Res. Ext. Center