Agronomy Talk

Agronomy Talk: SPRING FREEZE DAMAGE TO WINTER WHEAT

Published on Tuesday, April 09, 2019

CLICK HERE FOR A DOWNLOADABLE VERSION OF THIS AGRONOMY TALK UPDATE

 

Cold weather prevents wheat plants from breaking dormancy, so in cold springs, wheat crops may be slow to greenup. Delayed greenup is less concerning than cold damage to the wheat crop.

Chilling injury is only one part of the evaluation of winter wheat in the spring. If the fall was wet and challenging, there could be stand establishment concerns. In some low areas, the seed may have rotted in the fall. If the plant has fewer than three developed leaves going into the winter, it is more prone to injury as the crown is underdeveloped.

Shallow-planted wheat is vulnerable to heaving as the freezing and thawing of the ground pushes the seed or the crown of the root out of the soil, exposing the roots. Some of these plants could survive and produce adequate yield, but they will be very susceptible to the weather.

Late Cold Weather on Wheat:

Cold weather late in the spring can cause yield damage to wheat. Knowing how to properly growth stage your crop can help you determine if the cold weather caused any permanent damage.

At the Feekes 5 growth stage, the wheat plants are safe from cold weather damage but at the Feekes 6 growth stage, they are vulnerable.

The easiest way to stage your wheat crop is by pinching your fingers at the bottom of the stem and pulling up, feeling
for a bump. If you find one, that is the growing point or joint, meaning that the plant has reached the Feekes 6 growth
stage. Right above the joint is the developing head of the plant. If you have not applied nitrogen yet, work to make sure applications are made before the plant reaches Feekes 6 if possible.

The wheat head inside the leaf sheath is susceptible to cold damage. The extent of damage is a function of how cold the air temperature was and the period of time the plant was exposed to the cold temperature.

Carefully split open a wheat plant to see if the cold weather has damaged the head. If the head is white or green and
solid, it most likely has not been damaged. If it is yellow and soft, damage has been done. Most of this damage will be difficult to see until the weather warms up and the plants start to grow. Damage at the Feekes 6 growth stage will be sporadic throughout the field, depending on how the far temperatures dropped in relation to landscape position.

Wheat is a tough plant and you will be amazed at how well many fields will handle a cold spell. The extent of damage is not visible until a week or two after the cold snap, so be patient.

Management Moving Forward

  • Evaluate wheat stands for cold weather injury once the weather has warmed and the plants have resumed growth.
  • Be sure to evaluate the main stem; it has higher yield potential and will be further developed than the tillers.
  • Tillers will compensate for injury or loss of the main stem; damage to the main stem does not condemn the whole crop.
  • Apply spring nitrogen before the Feekes 6 growth stage to avoid the plants becoming rank.

 

CLICK HERE FOR A DOWNLOADABLE VERSION OF THIS AGRONOMY TALK UPDATE

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