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In this Issue: May 3, 2004 |
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Wheat Disease Update |
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Wheat Disease Update Powdery mildew continues to dominate the concerns of most producers throughout the eastern two thirds of Kansas. Maturity of the crop ranges from flag leaves just emerging in the northern counties to heading in the southern counties. Risk of yield to powdery mildew is a function of the severity of disease, the susceptibility of the variety, the value of the crop (seed production and high yield potential fields), and the weather conditions. If mildew severity is high, the flag leaves are emerging, the value of the crop is high (seed production and/or greater that 45 bu/ac yield potential), and weather conditions remain favorable, then a fungicide application will likely be profitable. Several products are available and effective. Most have an application window that closes at flowering; check the label. We are now receiving samples with virus symptoms from several areas of the state. Most appear to be Wheat Streak Mosaic Virus. This is not surprising in light of the magnitude of volunteer wheat that was not managed this past year. A virus screen is underway (check next week’s Alert for results). Leaf rust is becoming more prevalent in central Kansas on lower leaves at low severity (one to a few pustules per leaf). We have had a few unconfirmed reports of stripe rust in southwest Kansas (low incidence). Several fields are showing effects of poor root development, probably resulting from conditions last fall or late winter/early spring. At least one field in central Kansas is severely affected by Take all. A predictive model (80% accuracy) for Fusarium head blight (also known as scab) has been developed by Penn State University and Ohio State University. It provides risk assessments for most states east of the Rockies. According to that model, this week the risk for Kansas is predicted to be low throughout the state except for two small areas; the risk is medium in southwestern Sedgewick County as well as in northwestern and southwestern Sumner County. If the weather pattern continues to provide cool to moderate temperatures (65-85 F) and wetness from rain or dews, then fields that are flowering are at risk. If the field is in an area that experienced head blight in past years and the above conditions exist, then a fungicide application may be necessary to protect the crop. (Stack) |
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Web updated 9/01/06 |