Number 325 November 10, 2011

Transcription

1 Number 325 November 10, What to look for in fall wheat growth and development 1 2. Chloride and sulfur as topdressing nutrients for wheat 3 3. New herbicide-resistant crops under development 6 4. Comparative Vegetation Condition Report: October 25 November What to look for in fall wheat growth and development Generally speaking, wheat in most of Kansas got off to a slow start this year. This would be a good time to take a close look at your wheat, and see how well it has developed so far. You ll want to look at not just the topgrowth, but at the root systems. This plant has two tillers and one main stem. It is growing well. But look at the root system. It is not well enough developed to be grazed, and may be susceptible to nutrient deficiencies or desiccation damage over the winter if the crown roots do not get more developed. Photos by Jim Shroyer, K-State Research and Extension. You can see a small tangle of roots 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. These roots take up most of the water and nutrients the plant will need, and 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 1

2 the soil. This may be a common situation this year, especially with wheat that either came up late or did not receive moisture until recently. The photos below illustrate various degrees of what you d like to see when you examine your wheat this fall. In this photo, some of the crown roots are over an inch long. If the weather is mild for a couple more weeks, the roots should grow even more, which would be desirable. This is what you re looking for and hoping to see as the wheat crop heads into winter. The crown roots are now fully developed and able to provide water and nutrients to the plant. 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 2

3 2. Chloride and sulfur as topdressing nutrients for wheat With wheat topdressing season soon approaching, producers may be wondering if it would pay to add chloride or sulfur to their topdressing blend this year. Both are highly mobile nutrients in soils so split or topdress application may be beneficial, especially in regions of sufficient precipitation or with coarse texture soils that may cause leaching. Chloride One of the main benefits from good chloride (Cl) nutrition is the improvement in overall disease resistance in wheat. Wheat response to chloride is usually expressed in improved color, suppression of fungal diseases, and increased yield. It is difficult to predict whether chloride would significantly increase wheat yields unless there has been a recent soil test analysis for this nutrient. Chloride fertilization based on soil testing is slowly becoming more common in Kansas. As with nitrate and sulfate, chloride soil testing is recommended using a 0-24" profile sample. More field testing is needed, particularly in western Kansas, to determine the extent of the chloride-deficient areas, and to improve soil test correlations and calibrations. But based on current data, the probability of a response to Cl in dryland wheat production in northeast and central Kansas seems higher than in western Kansas. The interpretation of the Cl test and corresponding fertilizer recommendations for wheat are given in the table below. Chloride fertilizer is recommended when the soil test is below 6 ppm, or 45 pounds soil chloride in the 24-inch sample depth. Potassium chloride (potash) and ammonium chloride are the most commonly available and widely used fertilizer products, though other products such as calcium, magnesium and sodium chloride can also be used. Soil Test Chloride Interpretations for Wheat in Kansas Soil Chloride in a 0-24 inch sample 3 Chloride Recommended Category lbs/acre ppm lbs Cl/acre Low <30 <4 20 Medium High >45 >6 0 Deficiency symptoms appear as leaf spotting and are referred to as physiological leaf spot. K-State has done considerable research on Cl applications to wheat since the early 1980 s, mostly in the eastern half of the state. Results have varied, but there have been economic yield responses in almost all cases where soil test Cl levels have been less than 30 lbs/acre. Deficiencies were most likely to be found on fields with no history of potash (KCl) applications. Early studies showed that there are variety differences in response to Cl, but no recent studies have been done on this. Reports on the majority of these studies can be found in the Kansas Fertilizer Research Reports, published annually and available on-line at For more information, see Chloride in Kansas: Plant, Soil, and Fertilizer Considerations, MF2570:

4 Sulfur Sulfur (S) deficiency on growing crops is often mistaken for nitrogen (N) deficiency. With S deficiency, wheat becomes uniformly chlorotic. Like N, deficiencies normally occur in patches in the field -- especially areas where erosion has occurred, soil organic matter is reduced, or leaching is more pronounced. The pale yellow symptom of S deficiency often appears first on the younger or uppermost leaves, while N deficiency initially appears on the older, lower leaves. Deficiencies of S are often difficult to identify because the paling in crop color is not always obvious. Crops lacking S also may be stunted, thin-stemmed, and spindly. In the case of wheat and other cereal grains, maturity is delayed. Sulfur-deficient wheat in the early spring. Photo by Jim Shroyer, K-State Research and Extension. Sulfur is usually present in relatively small amounts in soils, and a majority is in organic forms. Sulfur-deficient soils are often low in organic matter, coarse-textured, well-drained, and subject to leaching. In recent years, an increasing number of finer-textured soils have shown S deficiency, however. A soil test for available sulfate-s in the soil profile is useful and should be done prior to planting. For proper interpretation of this test, soil organic matter, soil texture, the crop to be grown, and the expected yield level also need to be factored in to accurately assess S needs. Since sulfate-s is mobile, sampling to a 24-inch depth is important. Accurate estimates of S needs cannot be made from a surface sample alone. 4

5 Significant amounts of plant-available sulfate-s can be added to the soil through irrigation water. In Kansas, the S content of irrigation water varies, but in some cases enough S could be added through irrigation to meet crop needs. The S content of irrigation water should be determined by testing and factored into S applications. The timing of irrigation may not coincide with plant S needs, however. If it is well into the growing season before the first irrigation is made, the plant may be S deficient early, even though more than enough S will eventually be applied during the growing season. There are many S-containing fertilizer materials available. Several dry materials are available which can be blended with dry phosphorus or nitrogen fertilizers for preplant or winter/spring topdressing. Ammonium sulfate ( S) is a dry material that is a good source of both N and S, but has high acid-forming potential, and soil ph should be monitored. * Elemental S (typically percent S) is a dry material marketed by several manufacturers. Before it becomes available for plant uptake, elemental S must first be oxidized by soil microorganisms to sulfate-s and this can be a slow process when surface-applied. So it is probably best suited for preplant applications. * Gypsum (analysis varies) is calcium sulfate, and is commonly available in a hydrated form containing 18.6 percent S. This material is commonly available in a granulated form that can be blended with other materials. Since it is a sulfate source, it would be immediately available, and is suitable for spring topdressing. There are also liquid sources of sulfur fertilizers available. * Ammonium thiosulfate ( S) is the most popular S-containing product used in the fluid fertilizer industry, as it is compatible with N solutions and other complete liquid products. * Potassium thiosulfate ( S) is a clear liquid. Potassium thiosulfate (KTS) can be mixed with other liquid fertilizers. Application guidelines supplied by the manufacturers of both products caution that these products should not be applied directly to seed, by in-furrow or pop-up application, due to germination and seedling injury concerns. They also caution that these products should not be applied in a foliar application or as foliar sprays to growing plants. Topdressing with thiosulfate and UAN can be done early, before Feekes 5, and at temperatures below 70 degrees. But some burn can be expected, especially with KTS. For more information see Sulfur in Kansas For estimations of required application rates of S see Soil Test Interpretation and Fertilizer Recommendations -- Dorivar Ruiz Diaz, Nutrient Management Specialist ruizdiaz@ksu.edu -- Dave Mengel, Soil Fertility Specialist dmengel@ksu.edu 5

6 3. New herbicide-resistant crops under development There has been a lot of interest in the development of new crop cultivars with resistance to a wider range of herbicides than is currently available. Here is a quick summary of what is in the pipeline, and when these new crops might reach the market. * ALS-resistant grain sorghum. K-State has released to sorghum breeding programs a line of grain sorghum that is resistant to ALS herbicides. DuPont is developing the ALS herbicide for these new ALS-resistant grain sorghum hybrids. Currently, residue work must be completed before the herbicide can be registered. When commercial hybrids with this herbicide-resistant trait are on the market producers will have new opportunities for postemergence grass weed control. It is very unlikely that this technology will be available during the next 2 years. * DHT corn, soybeans, and cotton. DHT traits are being developed by Dow AgroSciences that confers resistance to both 2,4-D and aryloxyfenoxypropionate (the fop grass herbicides) in corn, and 2,4-D resistance in soybeans and cotton. Provided the new low volatility formulation of 2,4-D herbicide under development receives registration, a limited amount of DHT corn could potentially be available for the 2013 growing season. DHT soybeans and cotton are targeted for release in 2014 or DHT soybeans and cotton could be treated with 2,4-D for weed control, and could alleviate concerns about herbicide drift onto the crop from adjacent applications of 2,4-D. * Dicamba-resistant soybeans and cotton. This new GMO technology, being developed by Monsanto Company, would allow direct application of dicamba to soybeans and cotton to help address glyphosate-resistant weeds, as well as alleviate concerns about dicamba drift onto this new type of soybean and cotton. Dicamba-resistant soybeans could be available as early as Dicamba and 2,4-D resistant soybeans and cotton are not cross-resistant, so application of dicamba on DHT crops or 2,4-D on dicamba-resistant crops would still result in severe injury or plant death. As mentioned above, new formulations of dicamba and 2,4-D are being developed with reduced volatility, but spray drift will still be a concern onto susceptible or non-resistant crops. * HPPD resistant soybeans. GMO soybeans with resistance to the HPPD-inhibiting class of herbicides are also in development. No HPPD herbicides are currently available for use in soybeans, so this would provide a new mode of action and allow for greater diversification of weed control options to help manage herbicide resistant weeds. HPPD-resistant soybeans likely will not be available before 2015 at the earliest. -- Dallas Peterson, Weed Management Specialist dpeterso@ksu.edu -- Curtis Thompson, Weed Management Specialist cthompso@ksu.edu 6

7 4. Comparative Vegetation Condition Report: October 25 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. Two short videos of Dr. Kevin Price explaining the development of these maps can be viewed on YouTube at: The objective of these reports is to provide users with a means of assessing the relative condition of crops and grassland. The maps can be used to assess current plant growth rates, as well as comparisons to the previous year and relative to the 21-year average. The report is used by individual farmers and ranchers, the commodities market, and political leaders for assessing factors such as production potential and drought impact across their state. The maps below show the current vegetation conditions in Kansas, the Corn Belt, and the continental U.S, with comments from Mary Knapp, state climatologist: 7

8 Map 1. The Vegetation Condition Report for Kansas for October 25 November 7 from K-State s Ecology and Agriculture Spatial Analysis Laboratory shows that some snow fell over the western portions of the state. Generally, the level of photosynthetic activity has slowed, as would be expected as we move into the winter. Benefits from the moisture this week won t be apparent until the next period. 8

9 Map 2. Compared to the previous year at this time for Kansas, the current Vegetation Condition Report for October 25 November 7 from K-State s Ecology and Agriculture Spatial Analysis Laboratory shows that the level of photosynthetic activity is lower this year, with the exception of Greeley and Wichita counties in west central Kansas. The decrease is particularly noticeable in the eastern third of the state, as drought impacts in this region deepen. 9

10 Map 3. Compared to the 22-year average at this time for Kansas, this year s Vegetation Condition Report for October 25 November 7 from K-State s Ecology and Agriculture Spatial Analysis Laboratory shows that aboveaverage photosynthetic activity is present in a small portion of west central Kansas, as well as parts of central Kansas. Warmer-than-average temperatures in October have allowed for more photosynthetic activity than average. 10

11 Map 4. The Vegetation Condition Report for the Corn Belt for October 25 November 7 from K-State s Ecology and Agriculture Spatial Analysis Laboratory shows that photosynthetic activity has been reduced in all except the southern regions of the area, and upper Minnesota through upper Wisconsin and the Upper Peninsula of Michigan. In these northern regions, warmer-than-average temperatures have favored biomass production. Snow was a feature in the western portions of the Corn Belt, with some areas receiving as much as a foot. Snow cover did not persist. 11

12 Map 5. The comparison to last year in the Corn Belt for the period October 25 November 7 from K-State s Ecology and Agriculture Spatial Analysis Laboratory shows that the impact of drought conditions are particularly evident in eastern Kansas and northern Missouri. In contrast, the lingering high level of soil moisture in the eastern part of the Corn Belt is also evident. 12

13 Map 6. Compared to the 22-year average at this time for the Corn Belt, this year s Vegetation Condition Report for October 25 November 7 from K-State s Ecology and Agriculture Spatial Analysis Laboratory shows the northern regions have the biggest increase in photosynthetic activity. This region has averaged much-abovenormal temperatures for the period. This favored more biomass production than is typical at this time of the year. North Dakota temperatures average 4 to 6 degrees above normal, while temperatures in Minnesota average 6 to 8 degrees above normal. 13

14 Map 7. The Vegetation Condition Report for the U.S. for October 25 November 7 from K-State s Ecology and Agriculture Spatial Analysis Laboratory shows that both the Inter Mountain West and the East Coast had snow during the period. While this is typical in the West, it was unusually early for the East Coast. The area of greatest photosynthetic activity is in the Southeastern U.S., where the growing season is still in place. 14

15 Map 8. The U.S. comparison to last year at this time for the period October 25 November 7 from K-State s Ecology and Agriculture Spatial Analysis Laboratory shows that the biggest increase in photosynthetic activity is in Idaho and western Wyoming. Noteworthy is the decreased photosynthetic activity in eastern Kansas and northern Missouri, as the southern drought begins to influence these regions. 15

16 Map 9. The U.S. comparison to the 22-year average for the period October 25 November 7 from K-State s Ecology and Agriculture Spatial Analysis Laboratory shows that much of the country has greater photosynthetic activity than average. Texas continues to show below-average productivity, as recent rains have had only marginal impact on the long-term drought conditions. Central Oklahoma has experienced more benefit from the recent rains. Note to readers: The maps above represent a subset of the maps available from the EASAL group. If you d like digital copies of the entire map series please contact us at kpprice@ksu.edu and we can place you on our list to receive the entire dataset each week as they are produced. The maps are normally first available on Wednesday of each week, unless there is a delay in the posting of the data by EROS Data Center where we obtain the raw data used to make the maps. These maps are provided for free as a service of the Department of Agronomy and K-State Research and Extension. -- 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 16