In general, the 2000-01 Indiana wheat crop went into dormancy in good condition. The November and December temperatures were lower than normal, which resulted in very few fields with excessive top growth. In mid December, snow fall of 1 inch or more was recorded across the entire state and remained for about one month. This snow cover was sufficient to protect the wheat crop from the sub zero temperatures that occurred during the last two weeks of December. Since the snow has melted, temperatures have dipped to single digits on only two or three occasions. In the Lafayette area, the wheat crop looks good but temperatures have not yet been warm enough for wheat to break dormancy and begin to grow. In the southern one-third of Indiana, temperatures have warmed to the point where some fields have broken dormancy and are beginning to grow very slowly.
If you are curious whether your wheat has broken dormancy, there are two ways of making this determination when examining wheat plants. First, carefully wash the roots of a wheat plant and look for new root growth from the crown area of the plant. These roots should be snow white and may be very short (1/4 to 1/2 inch) if the plant has just broken dormancy. Secondly, look closely at the top two leaves of the plant. You should be able to see a line across the leaf at the point where the leaf was covered by the leaf sheath. The area below the line is the new growth and can be characterized by a brighter or shiny appearance when compared with the area above the line.
To date, it is our opinion that the Indiana wheat crop has not suffered any injury. However, each time wheat breaks dormancy and grows for a short period of time before re-entering dormancy, root reserves are lowered and therefore the vigor of the plant declines making it vulnerable to winter decline and perhaps death as a result of Rhizoctonia. The intermittent freezing and thawing that has occurred the past week can result in severe heaving of the plants on wet, poorly drained or heavy soils.
As the wheat begins to break dormancy, it is time to top-dress with nitrogen as soon as soil conditions permit. Assuming that 20 pounds of nitrogen were applied at seeding time, the rate of top-dress nitrogen is directly related to yield potential. With a yield potential of 50 bushels per acre, we recommend 40 lbs. of N as a top- dress, at 70 bu/ac we recommend 60 lbs. of N and at 90 bu/ac, 90 lbs. of N. On soils with a cation exchange capacity less than 10, the N rate may need to be increased by 10-15 lbs./ac. When top dressing, we recommend the use of dry materials or the use of streamer bars when using liquid materials. Every effort should be made to keep as much of the nitrogen fertilizer off the wheat leaves as possible. Nitrogen fertilizer applied to a plant with lowered vigor and dead leaf tissue could cause a significant Rhizoctonia problem.
For other
information about corn, take a look at the Corn Growers Guidebook on the World
Wide Web at http://www.kingcorn.org