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| Field Crop Advisory Team Alert newsletter | |
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| Vol. 23, No. 1, March 20, 2008 |
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| In this issue 2008 weed control guide for field crops available online New herbicide options in corn and soybeans New weed scientist New MSU nitrogen recommendation for field corn Use your soil nutrient bank Early season fungicide use on wheat for foliar diseases Sprayer calibration is important Check your planter before you go to the field New pesticide applicator core manuals available Market Outlook and Probabilistic Price Forecasts on the Web |
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| Starting up the season Ready or not, spring is rapidly approaching and its time to start publishing the Field Crop Advisory Team Alert newsletters. This issue offers advice for getting the best from your planter and sprayer, updated recommendations for judicious use of fertilizer, and a summary of new herbicides along with label changes for existing products. Our Internet readers will want to note that beginning this month we intend to post articles throughout the week as we receive them from authors. In the past, articles were collected and then published on the web and in print once a week. We appreciate suggestions from you, our readers. Please feel free to contact Andrea Buchholz at (517) 353-4703 or email catalert@msu.edu. Internet readers can also sign up to receive a brief email when we post new issues on the Internet. Details are at: http://ipm.msu.edu/email-field.htm We look forward to joining with MSU’s faculty and educators to provide you information this season for a successful harvest. – Joy Landis, editor, and Andrea Buchholz, assistant editor. |
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2008 weed control guide for field crops available online This year there are several new glyphosate formulations that can be used in Roundup Ready (glyphosate-resistant) crops. The table on pages 138 and 139 contains a list of all products that were labeled for use in Michigan as of the printing of the 2008 Weed Control Guide. This table contains the manufacturer of the product, formulation, product equivalent rates, and whether a surfactant needs to be included for maximum weed control. |
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| New herbicide options in corn and soybeans Since the release of the 2008 Weed Control Guide for Field Crops, several new herbicides have been registered for the 2008 growing season in corn and soybean. Below is information on some of the new products you will hear about this season. New registrations or label changes that occurred prior to publishing the weed control guide can be found in the article, “2008 weed control guide for field crops available online.” Corn herbicides Laudis 3.5L (tembotrione + safener) is new active ingredient being marketed by Bayer CropSciences. Laudis at 3 fl oz/A can be applied postemergence from emergence to the V8 (8-collar) corn growth stage. Laudis needs to be applied with an adjuvant; methylated seed oil (MSO) at one percent v/v plus ammonium sulfate (AMS) at 8.5 lb/100 gal is preferred. Atrazine at 0.5 lb/A can be added to expand the spectrum of weed control, however crop oil concentrate (COC) should used instead of MSO in this tank-mixture. Laudis provides excellent control of broadleaf weeds including velvetleaf, pigweed, common ragweed, eastern black nightshade, and smartweed with the additional control of several grass species. It offers growers crop safety on field corn, sweet corn, popcorn and inbreds used in seed production. Require Q 59.19DG (rimsulfuron + dicamba + safener) is a new premix being marketed by DuPont. The typical use rate for Require Q is 4 oz/A which provides 1 oz/A of Resolve and 3.8 fl oz/A of Banvel. The added safener allows for postemergence applications of Require Q from four to 20-inch tall corn or from 2-collar (V2) to 7-collar (V7) corn, whichever is the most restrictive. The addition of non-ionic surfactant (NIS), COC, or MSO plus AMS at 2.5 lb/100 gal is needed for effective weed control. Require Q provides postemergence control of several broadleaf weeds and some residual control of grasses and pigweed. Resolve Q 22.4DG (rimsulfuron + thifensulfuron + safener) is another new premixture from DuPont. The typical use rate for Resolve Q is 1.25 oz/A which contains 0.9 oz/A of Resolve and 0.1 oz/A of Harmony SG. The added safener allows for postemergence applications from emergence to V7 (7-collar) or 20” tall corn, whichever is most restrictive. The use of a NIS, COC, or MSO + AMS at 2.5 lb/100 gal is required. Resolve Q can be applied alone or tank-mixed with other postemergence corn herbicides. Resolve Q provides postemergence and residual control of certain weed species Soybean herbicides Authority Assist 4L is a new premixture of Spartan (sulfentrazone) and Pursuit (imazethapyr) being marketed by FMC Corporation. Authority Assist can be applied early preplant, preplant, or preemergence. The application rate of Authority Assist depends on its intended use. Authority Assist can be used from 4 to 6 fl oz/A as a foundation treatment prior to glyphosate in glyphosate-resistant soybean or at higher rates up to 12 fl oz/A for longer residual weed control. At the higher rates, chances of soybean injury are greater and certain soybean varieties have been found to be sensitive to the active ingredients in Authority Assist. Consult your local seed provider about varietal sensitivities. Authority Assist at the 5 fl oz/A rate contains 4.16 fl oz/A of Spartan 4L and 0.6 oz/A of Pursuit DG. Authority Assist will provide control of some winter annual weeds and provides residual control of common lambsquarters, eastern black nightshade, pigweeds, smartweed, and velvetleaf. Do not apply Authority Assist more than three days after planting or soybean injury may occur. Do not use on coarse textured soils classified as sands with less than one percent organic matter. Rotation restrictions and precautions for Authority Assist are similar to restrictions for Spartan and Pursuit. |
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| New weed scientist I would like to introduce myself for those who have not heard of or met me yet. I am Wesley Everman, the new Extension weed specialist at MSU and I joined the Department of Crop and Soil Sciences January 1, 2008. I will be covering weed management in corn, forages and potatoes. As for a bit of my background, I am originally from northeast Iowa, however, I went to Purdue University where I received my B.S. in Agronomic Business and Marketing. During my undergraduate career, I had four internships with three agriculture chemical companies. Due to the interest created in the internships, I stayed at Purdue and received my M.S. in weed science looking at using remote sensing technology to detect herbicide applications in crops. I then went to North Carolina State University to study weed biology, competition, physiology and management. While obtaining my Ph.D., I worked on several studies using precision application and mapping systems as well as several on-farm trials mapping the frequency and distribution of several weed species. I plan to utilize the various skills I have obtained to add to the solid weed management group already at Michigan State. I feel my broad background will allow me to address the unique issues facing producers in Michigan. I am ready to help address any weed management or herbicide issues and approach questions and research opportunities with an open mind. Although I just started at the beginning of the year, I have already been alerted to several areas needing research in the weed science arena and plan to take action. We have several research projects investigating weed control issues in potatoes and alfalfa, and have identified areas of interest in corn as well. This is an exciting time to be in weed science due to discovery of new resistant weed species around the country and the renewed interest in herbicide discovery. These developments will hopefully mean new herbicides for growers in the next few years. There are several new compounds that I will be investigating for weed control in corn and potato. I plan to work with researchers in other disciplines to develop integrated pest management (IPM) approaches in all the crops I cover. I believe working with researchers in all aspects of crop production will be essential to identify problems as they arise and will lead to the development of management strategies in a timely manner. I also have an interest in the use of cover crops for weed suppression and as green manure. With increased interest in these practices, the interaction of cover crops with weed species will be important to investigate, as will the effects of various green fertilizers on weed – crop competition dynamics. It will be important to determine the impact weeds have on fertilizer utilization, regardless of the source, as fertilizer input costs continue to increase. I hope to be involved in many areas of weed management and contribute to improving the efficiency of crop production wherever I can. I am open to cooperative research and hope you will contact me as you encounter weed control issues, herbicide tolerance concerns, or any other topics you would like to discuss. Feel free to contact me by phone at 517-355-0271 ext. 1223 or by email at everman@msu.edu
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| New MSU nitrogen recommendation for field corn Nitrogen plays a significant role in the growth, development and yield of corn. From the mid-1900s until present time, supplemental inputs of nitrogen through various nitrogen sources, especially legumes and manufactured nitrogen fertilizers, have contributed greatly to improvement in corn yields in Michigan. The first increments of nitrogen additions result in large increases in grain yield, but with each succeeding increment added the increase in grain yield becomes less until no further increase in yield occurs from additional nitrogen. The nitrogen recommendation for corn is based on this principle. Many field studies have been conducted over the years to establish the nature of the relationship between corn grain yield and nitrogen addition. For many years, MSU’s nitrogen recommendations for corn were provided in tabular form based on the yield potential of the soil. More was recommended for soils with higher yield potentials. Studies indicated that, on average, 1.1 to 1.2 pounds of nitrogen was required to produce one bushel of corn. In the 1970s, the tabular information was used to create a linear nitrogen recommendation equation based on yield potential. This equation indicates that the amount of nitrogen required is related to the yield potential of the soil. However, the equation may give the mistaken impression that yield can be increased without limit by applying more nitrogen. This relation only applies within the bounds of the yield potential of the soil. Corn yield response data collected over the last 10 years show that new corn hybrids are more effective in utilizing nitrogen for producing grain. One bushel of corn is being produced, on average, with 0.8 lb of nitogen. Summarization of corn yield response to data in Michigan and other North Central corn producing states shows that the economic optimum nitrogen rate (EONR) is similar across a range of yield potentials. Many states have now adopted the maximum return to nitrogen (MRTN) approach to determine the appropriate amount of nitrogen to apply for corn. The cost of nitrogen increases linearly with rate whereas the increase in corn grain yield plateaus (Figure 1). Where the difference between the two lines is greatest is the MRTN nitrogen rate. The MRTN nitrogen rate is higher for corn after corn than for corn after soybeans, due to nitrogen benefit from the soybeans. The MRTN rate will also vary with the productivity or yield potential of the soil. The recommended amount of nitrogen varies with the nitrogen-to-corn price ratio. At a nitrogen-to-corn price ratio of 0.10, the MRTN for corn after soybean in Michigan and Minnesota is near 100 and 115 lbs nitrogen/a for medium/low productivity soils and high productivity soils, respectively. In Wisconsin, the similar values are 60 and 115 lbs nitrogen/a. For corn following corn, the nitrogen recommendations are near 135 and 150 for Michigan and Minnesota. For Wisconsin, the recommendations are 105 for medium/low productivity soils and 135 for high productivity soils. The range of nitrogen recommendation for ± $1.00 of the MRTN is approximately ± 15 lbs nitrogen /acre. As the nitrogen-to-corn price ratio increases, the MRTN recommended nitrogen rate decreases. Suggested nitrogen rates for corn grown in Michigan based on recent nitrogen response data and using the MRTN approach are given in Table 1. The more productive soils have soil conditions that are more favorable for root development and mineralization of nitrogen. Hence, higher yields can be attained in high productivity soils with only slightly more nitrogen fertilizer than in low to medium productive soils. These recommendations are significantly lower than previous nitrogen recommendations. Farmers may be hesitant to make a complete shift to these recommendations, but rather moderate their nitrogen rates based on a better nitrogen efficiency of new corn hybrids (0.8 lbs N/bu than the previous 1.1). To test the new recommendations, farmers should put in strips with the new nitrogen recommendation in comparison to their standard rate and compare yields and economic return. Research data indicates there is very good confidence the new recommendations will provide the best economic return on investment in nitrogen.
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| Use your soil nutrient bank With the significant increases in costs of phosphate and potash fertilizers since last season and with tight supplies, some reflection on recommended rates is in order. MSU’s recommendations for phosphate (P2O5) and potash (K2O) are based on the buildup and maintenance approach. In this approach, the most important soil test value is the critical value (CV). On average, when the soil test value is at the CV, there is sufficient P or K available in the soil to produce 95 plus % of maximum yield. This is usually very close to the point of maximum economic return. For P, the CV varies by crop. For corn, soybeans and most other field crops it is 15 ppm, and for wheat, alfalfa and other forage crops, it is 25 ppm. For K, the CV varies with the cation exchange capacity of the soil. At this point, applying more fertilizer will usually not improve yield, but if no P or K is added, the available level in the soil will decline. An adequate soil test or maintenance range has been established over which an amount of P or K equal to crop removal is recommend. For phosphorus, this range is 15 ppm beyond the CV and for K it is 20 ppm. When the soil test value is beyond the maintenance range, there is no need to apply addition P or K. For most field crops no P is necessary when the soil test value is over 30 ppm, and for wheat and forage crops this value is 40 ppm. With K, the soil test value above, which no K is needed, will range from 105 to 140 ppm depending on soil texture, sandy to clayey. When the P or K soil test value is below the CV, the recommended amount of that nutrient will include an amount to build up the soil test value to the CV over a four-year period, plus an amount equal to crop removal (maintenance). Crop removal information is available in the Nutrient Recommendations for Field Crops in Michigan bulletin E-2904, page 8. Due to higher prices and limited supplies, farmers should consider applying no more than crop removal. This will provide an adequate amount for top yields and maintain the current available P or K level in the soil. Over 75 percent of all Michigan soils used for crop production have more than adequate amounts of P. In many situations no or only a small amount of phosphorus in the planting time fertilizer is needed. Make use of the P in your soil bank. There is a greater potential for benefit from applying potassium (K) than for P. Only 25 to 30 percent of field crop soils contain more than adequate available K. With limited supplies of potash this year decisions may need to be made on how to allocate the potash you can get. Including 20 to 25 lbs K2O in planting time fertilizer can give improved early growth and K use efficiency, especially in reduced tillage or no-till systems, and allow a reduction in the amount being broadcast. Due to the nature of the yield response to applied K, it is best to apply a reduced amount (e.g. 75 to 80 percent of recommended amount) to all fields needing K rather than applying the full amount to some fields and a small amount to other fields. Soil test results provide a good guide for how best to allocate available fertilizer resources. Those that have soil test information from the past year or two are in a good position to fertilizer allocation decisions. There is still time before planting time to collect soil samples and get the soil test information for fields not recently tested. |
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| Early season fungicide use on wheat for foliar diseases With the current prices for wheat, there is interest in looking at all options to increase yield. The use of including early season fungicide applications and their possible contributions to yield has been a hot topic for discussion lately. However, it’s important to remember that fungicides work mainly to protect the yield potential that is already present. Fields with the highest yield potential stand to gain the most from a timely application of fungicide to manage specific foliar diseases that are present. The information in this article summarizes the results of a number of University research trials around the country. Early applications of fungicide applied at jointing (Feekes 5-6) are often made as a combined treatment with herbicides. The majority of university based research that looked at early season reduced rate applications for diseases like powdery mildew, leaf rust and leaf spots (Septoria, Stagonospora) found no significant yield advantage to an early season reduced rate of fungicide. Applications at jointing did not result in good disease control on the flag leaf during grain fill. If high levels of leaf rust are present early in the season, or if stripe rust is present, an early application may be warranted. (Stripe rust is not an every year occurrence in Michigan.) We had more of a normal winter with respect to temperatures and amounts of snowfall, compared with the previous two years. I have heard some concern about powdery mildew at recent meetings, especially on wheat that put on considerable growth going into winter. However, powdery mildew in fall doesn’t necessarily translate into disease pressure that reaches the flag leaf and impacts yield. Studies from multiple locations found that fungicide treatments for foliar disease were most effective when applied between flag leaf emergence and flowering. In most cases, effective disease control and yield protection can be achieved with one application to protect the flag leaf and /or the developing head. When foliar diseases are present above threshold levels, fungicide applications can improve yield. There are greater yield responses when disease pressure is high than when disease pressure is low. The fact sheet, Management of Foliar Wheat Diseases available at http://fieldcrop.msu.edu/provides guidelines for scouting and disease thresholds, along with efficacy ratings for fungicides for common foliar diseases. There is no substitute for going out and scouting your fields to evaluate disease levels before making a decision to apply fungicides. |
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| Sprayer calibration is important
Although Asian soybean rust was not positively identified in Michigan in 2007, it was found in nearby Ontario. Many farmers in Michigan did spray for weeds, and possibly spider mites, soybean aphids and perhaps tank-mixed manganese. Now that spring has arrived, this is an excellent time to “tune up” field crop ground sprayers. |
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| Check your planter before you go to the field As many folks have acquired new or newer equipment this year, or are planting soybeans for the first time, here are some thoughts and suggestions on planting equipment before you go to the field. Review the operator’s manual and check the settings on your equipment. Most planters and drills have adjustments for the type and size of seed to be planted. Take for instance many of the common drills used to plant soybeans and small grains. In addition to setting the seeding rate, you must also set the feed cup gates. To plant soybeans, the seed gate at the cup must be in the proper position. If it is in position to plant smaller seeds such as wheat, it will be too close or closed and soybean seed will be damaged as it is singulated, potentially lowering germination and viability of the seed. Check the condition of bearings and drive chains. It is aggravating to have bearings go bad when they cause the machine to stop functioning. It is also aggravating to have uneven or erratic stands which reduce yield potential. Bearings that are binding or are beginning to fail affect planter performance by not allowing the shaft to turn at an even rate. Roller chain with a few frozen links or sprockets with excessively worn or missing teeth can have a similar effect by allowing the chain to jump or skip. On new planters, check for excessive paint build up on drive components that may have been overlooked when the machine was in final assembly and setup. Drive shafts should rotate smoothly and evenly to turn the singulating mechanism smoothly and evenly, thereby dropping seed at an even rate. Opener disks and press wheels should be inspected for wear on a regular basis. Opener disks that have become too small may not open the seed furrow properly and can affect seed placement in the furrow. In addition, worn opener disks can also affect the flow of crop residues through the drill as it moves across the field. Small openers may allow residue to accumulate on drill components which could result in plugging or poor depth control. Check the drill manufacturer’s recommendations for disk opener specifications. Regardless of the type or manufacturer of the machine, review the operator’s manual annually and check the performance of the machine often during planting. Mistakes made at planting will haunt you for the rest of the year |
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| New pesticide applicator core manuals available The long-awaited, newly revised and rewritten pesticide applicator core certification manuals will be available for sale through the MSUE Bulletin office and through county Extension offices by April 1. These manuals are currently being printed and delivery is expected by the end of March. Unlike the old core manual, which combined the private and commercial certification information into one, the new manuals will be sold separately. The new bulletin number for the private core manual is E3007. The new bulletin number for the commercial core manual is E3008. Both will be sold at a retail cost of $30. They both consist of a Michigan-specific addendum shrink-wrapped with the National Pesticide Applicator Certification Core Manual. The Michigan Department of Agriculture has established a cut-off date of August 1, 2008 for taking the old core exam. In the interim, applicants will be given the choice of taking the old core exam or the new core exam depending on which manual they studied. |
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| Market Outlook and Probabilistic Price Forecasts on the Web MSU ag economist Jim Hilker posts his Market Outlook and Probabilistic Price Forecasts for Grain and Livestock on the Internet at: http://www.msu.edu/~hilker/index.html These are updated regularly, so please visit his web site if you'd like the latest information. |
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