No. 2/April 7, 1997
Wheat Crop Off to a Good Start
The wheat crop made only average or slightly below average growth last fall, but moderate winter weather was good for the crop. Survival and early spring growth are very good in most places, though some fields that were planted very late are only now starting to grow, and tillering in such fields will be limited. The early start to spring growth we had this year is generally favorable because heading early allows the crop to take advantage of more favorable growing conditions in May and usually means earlier harvest. One drawback to early growth is greater susceptibility to freezing that can occur later in the month of April.
One of the problems this spring has been the difficulty of getting nitrogen (N) on the crop in time. Farmers have adapted well, with many using "nontraditional" means of getting N on the crop. What if there is still no N on a field? Although the ability of topdressed N to increase tiller number has probably been lost by the time upright growth begins (as it has in the most of the state), tiller numbers may be adequate, especially if the wheat has not shown N-deficiency symptoms. Research has shown that it is beneficial to apply N all the way up to heading, though less N should be used as application is delayed. We don't have very good guidelines on how much to reduce N rates as application is delayed, but decreasing the intended rate by 10 pounds per week of delay from April 1 up to heading is a reasonable approach. Any form of N will work; uniformity of application and mechanical ability to get N spread soon should be primary concerns at this point. There is a potential for leaf burn from UAN solutions, but little solution tends to stay on the leaves if it is applied while leaves are upright, and cool weather tends to decrease injury. Not more than 50 to 60 pounds per acre should be applied as UAN on actively growing wheat, and only 40 to 50 pounds once the tip of the flag leaf emerges.
Emerson D. Nafziger, Department of Crop Sciences, (217)333-4424