Agronomy Talk

Agronomy Update

The Potential Effects of Hard Frost on Wheat

Published on Friday, April 24, 2015

Many areas of Ohio received record low temperatures on the morning of April 24. Temperatures dropped into the mid-20s in several areas of northern Ohio, while shattering previous lows by 5-7ºF in parts of central and southern Ohio (London for example). Many farmers may be wondering what (if any) effect will this have on their wheat crop.

The extent of damage you may see will vary based on a few factors such as: the stage of growth of your wheat crop, the variety planted, maturity, planting date, planting depth, and temperature.

Let’s discuss each of these in a little more detail.

Growth Stage: The further along the wheat crop is the less tolerant it is of freezing temperatures. The graph below from Kansas State shows the effect of freezing temperatures by growth stage. Wheat that is jointing will be more impacted than wheat at an earlier stage. Therefore wheat in southern Ohio may see more damage than wheat in northern Ohio.

(Wheat resistance to freeze injury (courtesy, AG Experimental Station & Cooperative Extension Services, Kansas State University, Manhattan, KA; adapted from A.W. Pauli))

The Variety Planted: You will see that there is a temperature range for each stage. Some varieties are more susceptible to damage than others. The relative maturity of the variety plays a role in this. Varieties with earlier maturity will come out of dormancy faster and progress through the different stages faster, so they will be further along and may incur more damage.

Planting Date: Wheat planted earlier in the fall could potentially suffer more damage. Early-planted wheat will come out of dormancy at a more advanced stage than late-planted wheat. In most cases, early planting has a big advantage because you get more fall tillers and a more developed root system to combat heaving in the spring. However this year, early maturity varieties planted in the fall will probably be at the highest risk.

Planting Depth: Planting depth may also play a role as wheat develops a nodal root system (similar to corn). If the wheat is planted shallow and the crown area (which is where the growing point is) freezes, this can cause some damage. Hopefully there are enough tillers developed which can help to protect the crown area.

The extent of damage may not be known for a few days. The plant and the leaves may turn brown but more than likely, it will survive. The growing point is what you need to check. If the growing point is still firm and green after a few days, then it will survive. If the growing point is brown and mushy, the head is probably dead.



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Mark Apelt

Mark Apelt

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