"It's just a little yellowing of the leaf," some will say. "What's so bad about that?" Diseases like stripe rust affect wheat from time to time. While it may look like just a little bit of yellow or brown of the leaf, such diseases can cut yields by almost half.
You see, the first leaf to come out on a wheat plant is called the flag leaf, and the flag leaf is responsible for making the wheat head. If the leaf is compromised or even destroyed, that head will be small and stunted.
You can see the difference in the photo below. The first set of wheat stalks has been treated with fungicide. The flag leaf is fat, green, and upright. You can see the kernels at the top of the plant. They are vigorous and plump. As long as that flag leaf stays green and healthy, the wheat heads will continue to fill.
The second and third groups of stalks, from different fields, have not fared so well. The flag leaf is shriveled and brown. There won't be any more filling of those wheat heads. The wheat kernels in these stalks don't look nearly as appealing.
When you see this the difference up close, then you realize why a little leaf could be so important! ... See moreSee less