Number 271 November 12, 2010

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1 Number 271 November 12, Poor root growth seen in wheat crop 1 2. What to look for in fall wheat growth and development 3 3. Comparative Vegetation Condition Report: October 26 November Poor root growth seen in wheat crop Wheat in many areas of Kansas this fall has been under stress. The field in the photos below, taken in south central Kansas on November 9, shows a general yellowing. Soil conditions were very dry at the time of the photo. Pulling up some of the plants revealed that the root system was underdeveloped, even though the plants had one or two tillers. These roots have been unable to grow and take up the nitrogen and other nutrients the plants need, either because of dry soil conditions or aluminum toxicity (low ph), or a combination of both factors, The result is that the plants are chlorotic. This field should be not grazed until conditions improve since the cattle could easily pull the plants out of the ground. Yellow wheat under very dry soil conditions in Reno County, November 9, Photos by Jim Shroyer, K- State Research and Extension. 1

2 The wheat shows classic symptoms of nitrogen deficiency, with lower leaves showing the most yellowing. Some purpling was also evident, which could be due to either aluminum toxicity or phosphorus deficiency. The nitrogen deficiency was not due to a lack of nitrogen in the soil. Rather, the dry soil conditions had caused the root system to be severely underdeveloped, with only a short, stubby primary root present on most plants. When moisture conditions improve, the plants should develop a more extensive root system (unless aluminum toxicity is also a problem), and the plants should begin to green up. 2

3 If this field gets some moisture yet this fall, the root system should be able to develop more fully, which should help the plants regain their normal color and vigor. If it rains but the plants do not regain their vigor, there are other problems in the field such as aluminum toxicity or lack of nitrogen. If a field such as this remains dry and the roots do not develop further before winter, the crop will be at risk of winterkill or severe stress from desiccation. -- Jim Shroyer, Extension Agronomy State Leader jshroyer@ksu.edu 2. What to look for in fall wheat growth and development Wherever wheat has below-average development this fall, producers may be wondering whether there is still time for the wheat to develop a good root system this fall and what, exactly, the root system should look like going into winter. Let s take a look at how a slow-starting wheat plant during a dry fall can recover if it receives good rains in November. This plant has two tillers and one main stem, similar to the wheat in the Reno County field from this year featured in the article above. It is growing well, except its root system is not well developed. The reason for this is the lack of rain. Photos by Jim Shroyer, K-State Research and Extension. You can see some roots that are coming out from the seed in the photo above. These roots are called seminal roots, which means they come out from the seed. 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 do all the work. In addition, there are several small protrusions coming out of the white area about an inch above the seed. Those are crown roots starting to grow, but they are having a hard time because it is so dry. These roots take up most of the water and nutrients from the soil, so they are very important for the plant to survive the winter. If a cow were grazing on this wheat, she would probably pull the plant out of the ground as she is eating the leaves. There aren t many roots holding the plant in the soil. Now, let s suppose this field gets a nice soaking rain in mid-november. That was the scenario several years ago, and the progress of the crop was photographed so that you can see how the 3

4 plants developed during November. Hopefully, this is how things will occur again this year in dry areas that get a good soaking rain this week, or soon. Despite the slow start, the crown roots starts growing several days after a rain in November. This can be expected unless dry soils alone were not the sole cause of the poor root growth. In this photo, some of the crown roots are now over an inch long. You can see the mud sticking to the roots. If the weather is mild for a couple more weeks, the roots should grow even more. Within a couple weeks after a rain, the plants that had looked yellowish begin to green up and start putting on a little more topgrowth to match the improved root development. There are more leaves and tillers than when the soil was dry and the root system was stunted. 4

5 This is what you re looking for and hoping to see as the wheat crop heads into winter. The crown roots that were just starting to grow after the November rains are now more fully developed and able to provide water and nutrients to the plant. This plant is in good shape for 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. -- Jim Shroyer, Extension Agronomy State Leader jshroyer@ksu.edu 3. Comparative Vegetation Condition Report: October 26 November 7 K-State s Ecology and Agriculture Spatial Analysis Laboratory (EASAL) produces weekly Vegetation Condition Report maps. These maps can be a valuable tool for making crop selection and marketing decisions. During the growing season, we have been including maps for Kansas, the Corn Belt, and the U.S. that show the difference between current vegetation conditions and the 21-year average for vegetation conditions. That allows you to see whether a given area is either more or less green than average in terms of biomass condition. As we move into the dormant season in most areas of the country, there will be fewer and fewer instances where an area of the country is either more or less green than average, simply because most vegetation is either harvested or dormant during the winter every year. During the late fall and winter months, therefore, we will be presenting maps that show the current vegetation conditions, rather than maps that show only the differences between current conditions and the long-term average. In this issue, we ll start out with (A) the maps that we ve been using throughout the growing season comparing current conditions to the long-term average. Then immediately following will be (B) the new current conditions maps (along with the map of Kansas comparing current conditions to last year s conditions). Starting next week, we ll present only the current conditions maps through the remaining fall and winter months, then convert back to the comparison maps. 5

6 A. The most recent VCR maps from EASAL comparing current conditions to the long-term average are below: Map 1. Compared to the 21-year average at this time, this year s Vegetation Condition Report for October 26 November 7, from K-State s Ecology and Agriculture Spatial Analysis Laboratory shows greener-thannormal conditions. Much of this is due to the later-than-average date of the first frost. Many locations didn t experience the first freeze until after October 23. 6

7 Map 2. The U.S. Corn Belt comparison to the 21-year average shows greater-than-normal biomass production through most of the Corn Belt. The exception is the continued drought stress seen in the northern part of Kentucky. 7

8 Map 3. During this period compared to the 21-year average, the Vegetative Condition Comparison shows greater-than-average biomass production across the country. B. The most recent VCR maps from EASAL showing current conditions are below: 8

9 Map 4. The Vegetation Condition Report for Kansas for October 26 November 7, from K-State s Ecology and Agriculture Spatial Analysis Laboratory shows, as would be expected, little active biomass production. Most of the biomass production is confined to the eastern areas of the state. The areas of low biomass in west central Kansas coincide closely with areas that have been identified as in moderate drought status in the latest U.S. Drought Monitor. 9

10 Map 5. Compared to last year at this time, this year s Vegetation Condition Report for October 26 November 7, from K-State s Ecology and Agriculture Spatial Analysis Laboratory shows greater biomass across much of the state. This is due mainly to the later frost date, and the earlier emergence of the winter wheat compared to last year when wet weather had delayed planting. As of November 7, 85 percent of the winter wheat had emerged, as compared to only 77 percent last year at this time. 10

11 Map 6. The Vegetation Condition Report for the Corn Belt for October 26 November 7, from K-State s Ecology and Agriculture Spatial Analysis Laboratory shows that only the upper Midwest, Missouri and the eastern regions of the Corn Belt have high levels of biomass still photosynthetically active. The white regions over North and South Dakota, and central Minnesota are the result of the late October snowstorm in that area. Some areas of North Dakota reported up to six inches of snow. 11

12 Map 7. The Vegetation Condition Report for the U.S. for October 26 November 7, from K-State s Ecology and Agriculture Spatial Analysis Laboratory shows areas of snow in the Cascades, the Inter Mountain West, parts of the Rockies, and in upper New England. Drought conditions are visible along the Mississippi River Valley, while neighboring areas are still seeing photosynthetically active production. -- Mary Knapp, State Climatologist mknapp@ksu.edu -- Kevin Price, Agronomy and Geography, Remote Sensing, Natural Resources, GIS kpprice@ksu.edu -- Nan An, Graduate Research Assistant, Ecology & Agriculture Spatial Analysis Laboratory (EASAL) nanan@ksu.edu These e-updates are a regular weekly item from K-State Extension Agronomy and Steve Watson, Agronomy e- Update Editor. All of the Research and Extension faculty in Agronomy will be involved as sources from time to time. If you have any questions or suggestions for topics you'd like to have us address in this weekly update, contact Steve Watson, swatson@ksu.edu, or Jim Shroyer, Research and Extension Crop Production Specialist and State Extension Agronomy Leader jshroyer@ksu.edu 12