Published on Friday, April 24, 2015
With the cold temperatures we experienced last week, I wanted to share some key points on the effects of freezing temperatures on wheat. Some of this information is courtesy of our regional product specialist in Ohio, Mark Apelt.
Early-planted wheat, (prior to 10/15/14) looks very good, has a good nodal root system that has developed, and is at a more advanced growth stage than late-planted wheat (after 10/15/14).
The early-planted wheat that is in good/excellent condition is approaching, or has reached, the Jointing stage (Feekes 6-7: Stem Elongation, at this point you can feel at least a node on the stem.)
The cold night temperatures we have gotten in the last couple evenings should not have a major impact on survival of early-planted wheat, however, it is a plant stressor. Wheat likes dry spring conditions with consistently warming temps, not large warm-cold temperature swings.
According to Purdue University research, it takes two hours of ~25°F temps for wheat in the Jointing stage to have growing points die. Leaves may turn slightly yellow and the effect on yield would be considered moderate to severe. We did not get this cold across the geography I cover on wheat that was in the Jointing stage, so most should be fine, with only the most advanced fields at risk for plant stress.
The chart below depicts the level of resistance wheat has to freeze injury. However, keep in mind that most wheat is somewhat behind the growth stage “calendar” that is depicted below.
Wheat resistance to freeze injury (courtesy, AG Experimental Station & Cooperative Extension Services, Kansas State University, Manhattan, KA; adapted from A.W. Pauli)
Killing off an Existing Wheat Stand
If you are thinking about killing off an existing stand of wheat, don’t wait too long to decide. The longer you wait, the tougher it is to kill.
Also, don't reduce glyphosate rates when killing off an existing stand of wheat! Use a glyphosate rate of 1.5 ae (acid equivalent)/A. It would probably be good to throw in some 2,4-D for glyphosate resistant lambsquarter and marestail control. It is best to wait until temperatures are consistently above 50°F for optimum control.
To improve control if rotating to corn, do not mix glyphosate with 28%. Also, use AMS to improve control, especially if you are using hard water.
Gramoxone® + 2,4-D + atrazine (1.5 ae/A) is more expensive than glyphosate + 2,4-D but may be quicker and less sensitive to temperature.
Gramoxone® is a registered trademark of a Syngenta Group Company
Author: Chad Kalaher
Categories: Agronomy, NE Illinois, NW Indiana
Tags: Beck's Blog, AgTalk, Chad Kalaher, Agronomy, Agronomy Update, agronomist, Beck's Agronomist, indiana agronomy, wheat fields, Illinois wheat, Indiana wheat, Illinois agornomy
Beck’s Hybrids team sales agronomist for 22 counties in NE ¼ of IL and 7 counties in NW IN. Raised on grain and livestock farm in southern IL. B.S. Agronomy 1995 – University of Illinois, M.S. Weed Science 1997 – North Carolina State University. Previous positions in seed industry as researc
Beck’s Hybrids team sales agronomist for 22 counties in NE ¼ of IL and 7 counties in NW IN. Raised on grain and livestock farm in southern IL. B.S. Agronomy 1995 – University of Illinois, M.S. Weed Science 1997 – North Carolina State University. Previous positions in seed industry as research agronomist, district, and regional sales manager.
Beck's Hybrids seed company provides high yield corn, soybeans, wheat and elite alfalfa. All seed products are protected by the Escalate™ yield enhancement system delivering higher yields, insect protection, improved stand, and seedling health. We give you access to every major supplier in the world, so you get the genetic diversity and trait protection you need from one company – Beck’s. A heritage built upon the hard work, faith and innovation of our family and family of employees.
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