Iowa State University Extension and Outreach

East-Central and Southeast Iowa Crop Information


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May 8, 2008



Alfalfa Winter-Kill


            Although winterkill is not as widespread as in NE Iowa, there are many fields along and north of Highway 30 where stands have been thinned or lost. The main culprit was probably the ice sheets that formed after the early January thaw. Hay prices are already climbing dramatically and Iíve heard some rent figures for alfalfa fields that are hard to believe, so if the stand can be thickened up with some oats or ryegrass, it might be preferable to paying the high price for hay.

            Some may consider taking one cutting and then planting the field to corn. Roundup (up to 44 oz/A of Weathermax or Powermax) can be sprayed and the field cut for hay as soon as 36 hours later, but for a better kill it would be best to wait at least 5 days after spraying before cutting. Other herbicides (like 2,4-D) CANNOT be mixed with the Roundup if the alfalfa is to be fed.




Plant Corn or Apply N?          


Some have finished with their corn planting with the 2-3 days of field work we had available this week, but others havenít started yet. Iíd lean towards getting the corn in the ground at this point and worry about getting the N on later. Unfortunately if too many people have this idea there may not be enough sidedress equipment or liquid or day materials to go around.


Another concern is how long do I have to wait after applying anhydrous before planting or tilling? As long as the anhydrous is applied 6-8Ē and the corn is planted 2Ē there shouldnít be a problem. Tilling usually isnít a concern either with shallow tillage like a field cultivator. Sometimes the zone expands more towards the surface if the seal is not good or the anhydrous isnít applied as deep as it should be which can lead to fertilizer burn on the corn seedlings. One way to reduce the impact is to apply the N at an angle to the row direction so entire rows of corn arenít taken out. John Sawyer and Roger Elmore have a nice article in the ICM News regarding these concerns at









            Certified Crop Advisors can obtain 5 hours of credit (including 2 hours of soil and water) by attending a special session in the morning followed by the afternoon tour at the ISU SE Iowa Research & Demonstration Farm near Crawfordsville on June 26. This will include a tour in the morning featuring the soil drainage research on the farm.  More details will be posted soon.



If you have any questions, please feel free to contact the Iowa State University Extension Office.

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Last Update: May 8, 2008
Contact: Jim Fawcett

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