University of Nebraska-Lincoln Extension, Institute of Agriculture and Natural Resources

April 7, 2006

Herbicide treatment window in wheat narrows

Correctly determining plant growth stage can help ensure you get the results you intended from pesticides. Generally growth regulator herbicides, such as 2,4-D and dicamba, are applied to wheat before it reaches the jointing stage. After jointing, the risk of injury from applying herbicides increases with the amount of time that has passed.

“Jointing” is when the wheat head begins to come up above ground. As it moves up the stem, it forms nodes or joints. You can feel the stem to identify these joints. Wheat in eastern Nebraska is nearing or has already entered the jointing stage while wheat in the Panhandle is 7-10 days from jointing.

Applying growth regulator herbicides – often the most common and most effective against a broad spectrum of broadleaf weeds – after jointing can cause wheat heads to become trapped in the boot, reducing the plant’s ability to pollinate and yield well. The farther up the stem the head is when growth hormone herbicides are applied, the greater the risk for injury.

Other herbicides can be used after jointing, but producers may pay more and get a narrower range of control.

Growth stage illustration representative of a wheat variety grown in the Midwest using Feekes scale with the appropriate Zadoks stage below. The specific time between stages, the number of leaves, and plant height may vary among varieties, environments, locations, planting dates, and planting patterns.

Resources

For further information on wheat growth stages and wheat production in Nebraska, check the online UNL resource, Wheat Notebook.

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Copyright 2006 by the University of Nebraska Board of Regents. All rights reserved.
Published by University of Nebraska-Lincoln Extension in the Institute of Agriculture and Natural Resources Cooperating with the counties and the U.S. Department of Agriculture.
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