Scouting wheat in November
Jim Shroyer, K-State Research and ExtensionPhoto 1. Wheat plant with only one, very short crown root on November 14, 2012 at the Agronomy North Farm near Manhattan. The crown root system should be much more fully developed by this point, but has been delayed by dry topsoil conditions. Wheat is in various stages of growth and conditions across Kansas this month, and producers should be scouting their fields to see how well the crop is developing, and whether there are any pests, weeds, or nutrient problems that could be solved later this fall or winter. Last week I found a couple of problems or abnormalities on wheat at the Agronomy North Farm north of Manhattan.
The first problem (photo 1) is poor growth of secondary roots, or crown roots. This lack of crown root development is due to dry topsoils. A wheat plant should ideally have a well-developed crown root system by now to help prepare it to survive the winter.
Jim Shroyer, K-State Research and ExtensionPhoto 2. Example of wheat with good crown root system. There are some primary roots coming out from the seed, although they cannot be seen in this photo. These roots are used to take up water and nutrients throughout the whole growing season, but there aren’t very many of these roots so that can’t support a plant with one or two tillers for very long. The crown root system is, or should be, much more extensive than the primary root system.
In photo 1 there is a small whitish protrusion angling out of the crown area about an inch above the seed. This is a crown root starting to grow. Crown roots take up most of the water and nutrients from the soil, so they are very important for the plant to survive the winter. By this point in the season, there should be a much more extensive crown root system than what I found on this plant. All we need is some moisture in the soil and these roots would quickly begin developing.
Photo 3. After another month’s growth, wheat from the same field as in photo 2 above has crown roots 9 to 10 inches long. This is what you’d like to see. The crown roots in these two photos (2 and 3), taken a few years ago, got off to a slow start due to dry soils (similar to this year), but grew quickly once the wheat received some moisture. In contrast to this, you can see what a well-developed crown root system looks like in photo 2, taken in early December a few years ago. This is what you’d like to see in your wheat crop before it goes into the winter. With all these roots the plant should be well anchored so that if cows were grazing the wheat they couldn’t pull the plants out of the ground.
Another thing I’ve seen this week at the North Farm is wheat with yellow banding on leaves due to cold temperatures (Photo 4). When temperatures are quite cold at the time tillers emerge, it can result in yellow banding on the leaves. If this is the cause of the yellowing, symptoms should eventually fade away. click image to zoomJim Shroyer, K-State Research and ExtensionPhoto 4. Yellow banding on leaves caused by cold temperatures when the leaves first emerged. This will fade away with time.