Ag Line: Color changes in wheat
By Wade Parker
County Extension Coordinator

As wheat prices continue on the uptrend, we want to make every bushel of wheat we possibly can! Wheat producers are experiencing different growth habits of their wheat this year. One of those different changes is a color difference in the plant, one from green to a brown or purple colored cast.

Why did wheat turn from green to a rusty color? There can be several explanations to the color change.

One of the possible reasons for this discoloration in the plant may be phosphorus induced. Research has demonstrated that all plants will exhibit a rusty color when phosphorus is in limited supply. Producers will need to look at their soil tests to determine if this condition exists. However, even if your soil tests are high in phosphorus, the 25-degree nights will cause phosphorus to be unavailable to the plant. The soils freeze and with that P will be tied up. That is why a starter fertilizer containing P contributes to healthy seedlings in any crop. Once the soils warm, then P will become available to plant use.

After a brief discussion with Dr. Dewey Lee, he informed me of a second possibility of wheat discoloration involving a sugar buildup in the plant. This sugar buildup contains a pigment known as anthocyanin. This pigment is a reddish to purplish colored pigment. Anthocyanin is found in most plants and is involved in color changes of plants in the fall of the year. Just like when leaves of our elm and oak trees change in the fall, anthocyanin is present in wheat leaves. When the sugars with anthocyanin present buildup in the wheat plant, we can see those same color changes in the leaves of wheat. This buildup was a direct result of a warm January, followed by a cold February. In other words, an abrupt change of temperature could cause sugars to buildup and not be metabolized in the plant.

Nevertheless, if you have not applied all of your Nitrogen, then I recommend 75-85 lbs. of N + herbicide of choice. This needs to be accomplished as soon as field conditions allow.

I feel our wheat crop has good potential, as long as the frost will stay away in the near future.