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| Field Crop Advisory Team Alert newsletter | ||||
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| Vol. 22, No. 2, April 12, 2007 |
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| Soybean seed applied inoculation Kurt Thelen and Terry Shulz, Crop & Soil Sciences Nitrogen fixation is a result of the symbiotic relationship of Rhizobia bacteria and soybean plants. These bacteria fix atmospheric N2 into the NH4 form, which is useful to the plant. In return, the plant provides the bacteria with carbon photosynthesis products (dicarboxylic acids), which the bacteria use as food. Establishing rhizobia or inoculation in a field that has never grown soybean is needed to ensure nitrogen fixation. Elmore (1996) suggests when and how soybeans should be inoculated, and provides recommendations on inoculate type to use. Soybeans grown on soils without a rhizobia population will use available soil nitrogen, and if soil nitrogen levels are low because of soil type, soil erosion, etc., the symptoms of nitrogen deficiency may occur. |
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| Field studies in Northern Michigan showed 45 and 23 percent soybean yield increases in 2004 and 2005 where inoculant was used and fields had not seen a previous soybean crop. Soybean plant coloration differences were obvious in this study, as inoculated plots appeared much greener. On other Michigan sites with a history of soybean cropping, soybean seed inoculation increased yield by an average of 1.3 bushels, with significant increases at 6 of 14 sites from 2003 to 2005. Because most commercially available inoculant products are relatively inexpensive, the 1.3 bushel/acre expected average yield increase will generally cover application costs. Therefore, it is recommended to apply Rhizobium inoculant to soybean seed each time you plant soybeans. This is especially true on sandy soils, where it is more difficult for the Rhizobia to survive from one season to the next. Also, it is important to inoculate on any soil if soybeans are to be grown for the first time. Two types of inoculants can be used: seed-applied and soil-applied. The seed-applied inoculate is more effective when mixed with water to form a slurry that is used to coat the seed. This should be done as close to planting time as possible, preferably within several hours. The soil-applied inoculate may be easier to apply than the seed-applied inoculate, but it is more expensive on a per acre basis. Thus, seed applied inoculant is generally the method of choice for most growers. In addition to the recommended short time period between seed applied inoculant application and planting, there are other potential challenges associated with proper soybean seed inoculation. Care should be taken in applying inoculant to fungicide or insecticide treated seed. Fungicide and insecticide labeling should be checked to ensure that the particular pesticide product is compatible with Rhizobium inoculant. Potter (2004) conducted field trials to examine the effects of inoculating soybean seed with rhizobium, seed applied insecticides and fungicides, and combining bacterial inoculant, insecticidal and fungicidal products in Southwest Minnesota. For the trial, one bacterial inoculant, two insecticidal products, and two fungicidal products were used. There were 12 treatment combinations among the 5 different products tested. The results showed that crop injury was not observed with any treatment. Further, differences in root disease, soybean height, nodulation or yield were not observed among treatments. A three-year Michigan study tested the effects of combinations of seed inoculant, fungicidal seed treatment and insecticidal seed treatment. Inoculant was used alone, in combination with either Apron Maxx, Cruiser, or Gaucho, and in combination with Apron Maxx and one of the two seed applied insecticides. Results of the trial showed that in fields where soybean seed inoculation did significantly increase yields versus non-inoculated seed, the addition of insecticidal and fungicidal seed treatments did not significantly negate the observed yield increases. View chart of Results from Soybean Inoculant/Fungicide Trials, 14 Michigan sites in soybean rotation, 2003-2005. Recommendations
Beuerline, J. (2004) Soybean inoculation; its science, use, and performance. http://agcrops.osu.edu/soybean/documents/SoybeanInoculation.pdf Elmore, R. W. (1996). Soybean Inoculation—When is it necessary? University of Nebraska. [WWW document].URL: http://ianrpubs.unl.edu/fieldcrops/g737.htm Potter, B. (2004). Yield effects of seed applied fungicide, insecticide and Rhizobium inoculants on soybean. University of Minnesota. Southwest Research and Outreach Center. [WWW document]. URL: http://swroc.coafes.umn.edu/SWMNPEST/04publications/yieldeffects/innoculant.htm |
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| New soybean management resources are available online Mike Staton MSUE Van Buren County The Soybean 2010 website has been updated to include new soybean management information aimed at helping Michigan soybean producers increase soybean yields and farm profitability. The site can be found at: http://web1.msue.msu.edu/soybean2010/. Nine, new soybean fact sheets covering key management topics were developed in 2007 and are posted on the Soybean 2010 website. Four of the fact sheets are especially timely as they cover calibrating soybean drills, risks, benefits and recommendations for early-planted soybeans, soybean seed inoculants and insecticide seed treatments. Links to other useful soybean management websites have been added to the Soybean 2010 webpage. Sources include: Michigan State University, Ohio State University, Iowa State University, Purdue University, University of Missouri, USDA and the Ontario Ministry of Food and Rural Affairs. Much of the information provided at these sites is adaptable to Michigan. The results of the 2005 Soybean 2010 grower survey are also posted on the website. The survey showed that high-yield producers used key management practices more extensively and consistently than low-yield producers. Soybean growers can use the survey results to identify management areas that may be limiting their soybean yields. Soybean 2010 was developed to help Michigan growers increase soybean yields and farm profitability. Funding for Soybean 2010 is provided by MSU Extension and the Michigan Soybean Promotion Committee. |
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| Management of foliar wheat diseases, Part 1 Diane Brown-Rytlewski and Willie Kirk Plant Pathology, and Martin Nagelkirk, MSUE Sanilac County The most important leaf diseases of wheat in Michigan include powdery mildew, Stagonospora leaf and glume blotch, Septoria leaf blotch, and leaf rust. Depending on conditions, a serious level of any one of these fungal diseases can cause a significant yield loss. Part 1 of this article on wheat foliar diseases covers powdery mildew, Septoria leaf blotch, and Stagonospora leaf and glume blotch. Part 2, which will appear in the April 26 issue of the Field Crop CAT Alert, will cover leaf rust, stripe rust and fungicides for managing diseases. A fact sheet, Management of Foliar Wheat Diseases, is available at: http://fieldcrop.msu.edu/documents/wheat%20foliar%20disease-final.pdf Leaf diseases affect yield by reducing the amount of green leaf area available to capture sunlight and make carbohydrates used during grain filling. The flag leaf is the most important in determining grain yield and quality, but heavy infections as early as the fully-tillered stage have been shown to lead to modest yield declines. Varietal resistance is the first line of defense in managing foliar disease of wheat. Michigan State University’s annual variety trial results for red and white winter wheat (back to 1997) include disease resistance ratings, and can be found at the website: www.css.msu.edu/varietytrials/wheat/. Use the tables to view field trial ratings and determine variety performance with respect to susceptibility or resistance to a particular disease. Cultural practices, particularly crop rotation, can serve to prevent or minimize disease development. Wheat should never follow wheat or other cereals, if at all possible. In addition, growers should avoid heavy fertilization with nitrogen as overly dense, lush stands tend to encourage leaf diseases. Planting wheat prior to the Hessian Fly Free Date may encourage the establishment of diseases such as powdery mildew and Septoria, and is an additional reason to delay planting. Fungicide application may be profitable when there is severe disease pressure, and a susceptible variety has been planted. Fungicide research trials have shown that under low to moderate disease pressure, many wheat varieties may not show an economic return when treated with fungicides. Foliar fungicides protect yield when disease pressure is severe. The best candidates for fungicide treatment are fields with the highest yield potential. Before using a foliar fungicide, growers should determine the yield potential of the wheat crop, and the straw, if it is to be marketed, and determine whether applying a fungicide is likely to be profitable. Management practices targeted toward specific diseases are listed under the specific disease headings. Scouting individual fields is critical to making sound management decisions. Inspect fields for disease before making a decision to apply fungicides. Check about 30 to 50 tillers randomly in the field to get a clear picture of the extent of disease present; avoid looking in just one or two locations. Powdery mildew (view images) Cause: On wheat- Erysiphe graminis f.s tritici (fungus). On barley- Erysiphe graminis f.s. hordei (fungus). These fungi are host specific. Symptoms: Powdery, white to light gray patches may appear on leaves and stems (especially upper leaf surfaces) any time after seedlings emerge. Black specks containing spores may form in the patches of mildew as the season progresses. Powdery mildew overwinters as resting spores on straw, stubble, volunteer or overwintering wheat. Conditions favoring the disease: Cool temperatures (59 to 72ºF) and high humidity (greater than 85%) are optimal for the development of the disease. Heavy nitrogen fertilization also enhances disease development. Management: Select resistant varieties. Avoid heavy amounts of nitrogen, which can stimulate rapid growth. Determine the need for fungicide treatment by scouting for powdery mildew at flag leaf emergence and the boot stage. The threshold is an average two to three spots per leaf (averaged over 30 to 50 leaves) on the leaf below the flag leaf. Septoria leaf blotch, Stagonospora leaf and glume blotch (view images) Causes: Septoria tritici and Stagonospora nodorum. (fungi). Symptoms: The first symptoms are tiny yellow flecks on the lower leaves. Septoria expands to angular, tan to brown lesions containing black, pinpoint specks (pycnidia, which produce spores). It does not infect the glumes. Stagonospora lesions are lens-shaped with yellow halos and may contain brown pinpoint specks (pycnidia) within the lesions. Stagonospora affects both leaves and glumes. On wheat heads, it starts as gray-brown spots on the chaff that become dark brown blotches with grayish-white centers on the glume. Conditions favoring the disease: These fungi overwinter on straw, living plants or seed. Spores are present in late summer and fall, and can germinate over a wide temperature range. Spores are produced during periods of wet weather and can cause infections throughout the growing season. Barley is generally less susceptible than wheat. Wet and windy weather favors the development of the disease. Septoria is more prevalent earlier in the season (at temperatures around 50-68°F), during the period from stem elongation to flag leaf emergence. Stagonospora tends to appear around heading (temperatures are in the 68-81°F range). Cool, wet weather during flag leaf emergence provides favorable conditions for severe outbreaks of this disease. Planting small grains as successive crops allows inoculum to build up in the field, especially under no till or minimum tillage. Management: Select varieties with resistance. Use certified seed. Seed treatment may help limit seedborne disease. Rotate out of small grains for two years. Avoid planting into wheat stubble. Determine the need for fungicide treatment by scouting at flag leaf emergence and the boot stage. The threshold is an average one to two lesions per leaf (averaged over 30-50 leaves) on the leaf below the flag leaf. |
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Challenges and options for giant ragweed management
Giant Ragweed Control in Soybean
PRE soybean herbicides (conventional-till soybeans):
POST soybean herbicides:
Giant Ragweed Control in Corn
PRE followed by POST programs (moderate to high populations):
It is important to consider control of other weeds, soil pH restrictions, rotations restrictions, and maximum allowable rates (i.e., atrazine) when designing a giant ragweed management program. If giant ragweed is not currently a problem in your fields, make sure to keep a watch out for those giant ragweed populations in undisturbed areas, such as fencerows, roadsides, and waterways. These areas can often times be the source of seeds to spread into fields. |
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| Updates from the 2007 Weed Control Guide for Field Crops Christy L. Sprague and David Hillger Crops & Soil Sciences (Editor’s note: View the guide on the Internet at: http://www.msuweeds.com/publications/2007_weed_guide/. You can also purchase a guide from your county Extension office or call the MSUE bulletin office to order at 517-353-6740.) The 2007 Weed Control Guide provides the latest up-to-date information on weed management recommendations in corn, soybeans, small grains, forages, dry edible beans, potatoes, sugar beets, and sorghum. Other features include: an up-to-date table on the current glyphosate products that are labeled for use in Michigan, information on rain-free periods of different herbicides, instructions on how to submit a sample to the diagnostic clinic, and a complete table on crop rotation restrictions. Additionally, seven fact sheets on the control of hard-to-control weeds are included in the guide (p. 163-171). The fact sheets contain the most current recommendations for control of dandelion, white campion (white cockle), horseweed (marestail), wild carrot, Canada thistle, common pokeweed and hemp dogbane. Additionally, this year there is a new fact sheet on identifying and controlling grasses in winter wheat. Information on the new herbicides for the 2007 Weed Control Guide is updated below. Corn (p. 18-54) There are three new herbicides added to the corn section of the Weed Control Guide in 2007. They were Impact (p. 29), Resolve (p. 25 & 40) and Stout (p. 39). Impact 2.8SC (topramezone) is a new postemergence herbicide for the control of most broadleaves and has some suppression of grasses. It is a “bleacher” herbicide that can be used on all types of corn including seed and sweet corn (Check with the seed corn companies before applying it to parent inbred lines.). The use rate recommended for Michigan is 0.5 oz/A. Rates higher than 0.5 oz/A will restrict planting soybeans into the treated area for 18 months in Michigan. The addition of ¼ to ½ lb of atrazine will improve the overall weed control of Impact. Resolve 25DF (rimsulfuron) is a compound that has been used in combination with other herbicides (Basis, Steadfast and Accent Gold) for several years. It has also been used in potatoes and tomatoes under a different name, Matrix. Resolve can be applied preemergence or postemergence on field corn only for the control of many grasses and some broadleaves. The recommend rate for either a preemergence or postemergence application timing is 1.0 oz/A. The addition of ¼ to ½ lb of atrazine postemergence will improve the overall weed control of Resolve. Non-ionic surfactant and ammonium sulfate are needed for effective post emergence weed control. Stout 72.5DF is a new mixture of two herbicides, Accent (nicosulfuron) and Harmony GT (thifensulfuron). Stout is a postemergence herbicide for the control most grasses and a few broadleaves. The application rate for Stout is ¾ oz/A. Crop oil concentrate and 28% liquid nitrogen are needed for effective weed control. Soybean (p. 55-89) The soybean section of the 2007 Weed Control Guide has been expanded to include new information on weed control options in no-till soybean (p.76-79). This section offers information on the burndown and residual activity of various herbicides and herbicide combinations. Additional information on fall herbicide applications has also been included. Five new herbicide names appear in the soybean section of the 2007 Weed Control Guide: Prefix CP (p. 58), Canopy 75DF (p. 51 & 77), Authority First (p. 60 & 77), Sonic (p. 60 & 77), and SelectMax 1EC (p. 72). Several of these herbicides are not new to the marketplace. In fact, none of these new products contain new active ingredients. Prefix CP is a new co-pack of Prefix (s-metolachlor) and Reflex (fomesafen) that is manufactured by Syngenta Crop Protection and registered for preplant and preemergence weed control in soybean. Typical application rates of Prefix CP are 1.1 pt/A of the Prefix component and 1 pt/A of the Reflex component. Prefix CP will provide 4 to 5 weeks of residual weed control and should only be used as a foundation herbicide prior to a postemergence herbicide application in a sequential weed control program. Weeds that are controlled in the initial 4 to 5 weeks after application include: excellent control of eastern black nightshade, pigweeds, wild mustard and most annual grasses and good control of common lambsquarters, common ragweed, and smartweed. Prefix CP should be applied with a burndown herbicide like glyphosate, 2,4-D ester, and/or Gramoxone to control weeds that have emerged prior to Prefix CP applications in no-till soybean. Restrictions and precautions for Prefix CP are similar to restrictions for s-metolachlor (Dual Magnum) and Reflex. Canopy 75DF is a premix formulation of chlorimuron (Classic) and metribuzin (Sencor) that can be applied in the fall, early preplant, preplant incorporated, or preemergence. Canopy is a replacement for Canopy XL for burndown and preemergence applications in soybean. Canopy’s labeled application rates range between 2.25 and 7 oz/A, however typical Michigan rates will generally be between 3 and 4 oz/A, unless the soil pH is above 7.0. If soil pH is between 7.1 and 7.6 the use rate of Canopy is 2.25 oz/A, DO NOT apply Canopy if the soil pH is greater than 7.6. As with all herbicides that contain chlorimuron, soil pH restrictions are important to consider for rotational crops. The rotation intervals are as follows: wheat 4 months, alfalfa 10 months, field corn 10 months, dry beans 12 months, and sugar beets 30 months. A 3 oz/A rate of Canopy contains 1.28 oz/A of Classic and 2.57 oz/A of Sencor. To compare Canopy to Canopy XL, 3 oz/A of Canopy would also contain the same amount of chlorimuron as 3.5 oz/A of Canopy XL. Canopy aids in the burndown of a number of broadleaf weeds. To obtain maximum burndown activity the addition of 1% v/v of crop oil concentrate is required and the addition of 1 pt/A of 2,4-D ester is recommended for control of horseweed (marestail) (Remember with 2,4-D ester a minimum of 7 days is needed between application and soybean planting.). Canopy provides residual control of several annual broadleaf weeds including lambsquarters, pigweeds, ragweeds, smartweed, cocklebur, jimsonweed and velvetleaf. Authority First and Sonic 70DF are two new premixes for preplant, preemergence or preplant incorporated use in soybean. Authority First is marketed by FMC Corporation and Sonic is marketed by Dow AgroSciences. Both of these products contain the same active ingredient at the same ratio, 62.1% of sulfentrazone (Spartan) and 7.9% of cloransulam-methyl (FirstRate). The typical use rate for these herbicides is 3.2 oz/A when used as foundation herbicide prior to a postemergence application in a sequential weed control program and 6.4 oz/A for use in a total preemergence only program. Authority First or Sonic should be applied with a non-ionic surfactant plus ammonium sulfate (AMS) or crop oil concentrate plus AMS in no-till soybean to control weeds that have emerged prior to preemergence application. Glyphosate and/or 2,4-D ester should be included to control a broader spectrum of weeds. Authority First or Sonic should not be applied after soybeans have emerged. Excessive rainfall immediately after application may cause soybean stunting. Weeds that are controlled by Authority First or Sonic include: excellent control of c. ragweed, pigweeds, smartweed, and wild mustard and good control of jimsonweed, common lambsquarters, giant ragweed, velvetleaf and eastern black nightshade. SelectMax 1EC is a new formulation of clethodim being manufactured by Valent that contains a built-in adjuvant package. This new formulation increases the flexibility in adjuvants that can be used when applying clethodim for postemergence grass control. Preferred adjuvant choices still include a crop oil concentrate or methylated seed oil at 1% v/v (but not less than 1 pt/A); however a non-ionic surfactant at 0.25% v/v can be used for certain tank-mixtures. The addition of ammonium sulfate at 2.5 to 4 lbs/A may be added to improve control of difficult to control weeds. The typical use rate for SelectMax is 9 fl oz/A. To control volunteer corn (4 to 12 inches tall) SelectMax should be applied at 6 fl oz/A. For tank-mixtures with glyphosate products specifically for control of volunteer Roundup Ready corn in Roundup Ready soybeans ammonium sulfate should be included at 17 lbs/100 gallons of spray solution plus additional adjuvants that are recommended on the glyphosate label. Small grains (p. 90-102) There were three new herbicides added to the wheat and small grains section of the Weed Control Guide in 2007. They were Affinity BroadSpec (p. 92), WideMatch (p. 93) and Osprey. Affinity BroadSpec 50DS is a new combination of Harmony GT (thifensulfuron) and Express (tribenuron) that provides similar control for most weed species controlled by Harmony Extra. The major difference between Harmony Extra and Affinity BroadSpec is that Affinity BroadSpec is a 1:1 ratio of Harmony GT and Express that translates to a lower relative cost per acre. The use rate for Affinity BroadSpec is 0.75 oz/A. Adjuvants are needed and will depend on tank mix partners. WideMatch 1.5L is a premix combination of Stinger (clopyralid) and Starane (fluroxpyr) for broadleaf weed control up to the boot stage in wheat, barley and oat without a legume underseeded. The recommended application rate is 1.0 to 1.33 pt/A. Osprey 4.5WDG (mesosulfuron) is a postemergence herbicide for the control of most grass and some broadleaf weed species in winter wheat. Osprey can be particularly useful for controlling annual bluegrass, annual ryegrass and windgrass along with a few broadleaf weeds. The use rate of Osprey is 4.75 oz/A and requires the addition of adjuvants for effective weed control. The type and rate of the adjuvants will depend on tank mix partners. Dry edible beans (p. 114-123) Two new herbicides were added to the dry edible bean section for the 2007 Weed Control Guide: SelectMax (p. 121) and Reflex (p. 119). SelectMax is described in the soybean section above. After over 10 years of Section 18s, Reflex 2L (fomesafen) has finally received full federal registration for use in dry beans. Recommendations for Reflex use in dry beans can now be found in the weed control guide. Reflex has been an important tool for Michigan dry bean growers for postemergence control of broadleaf weeds, particularly common ragweed and eastern black nightshade. All classes of dry beans are included on the label. Only one application of Reflex at 1 pt/A can be applied for weed control in a two-year period. A non-ionic surfactant at 0.25 to 0.5% v/v or a crop oil concentrate at 0.5 to 1.0% v/v must be included with Reflex for effective broadleaf weed control. Dry beans should be between the first and fourth trifoliate leaf stages at the time of application. Reflex applications should be targeted to control common ragweed up to four inches in height and nightshade species up to two inches in height (4 leaves). Reflex will also control pigweed up to two inches in height. Reflex will control ALS-resistant biotypes of these weeds. Additional weeds may be controlled by tank-mixing Reflex with other herbicides. If proper planting intervals are not observed, Reflex can cause injury to rotational crops. Wheat should not be planted for 4 months and corn should not be planted for 10 months after an application of Reflex. Sugar beets, cucumbers, and alfalfa cannot be planted for 18 months following a Reflex application. Potatoes (p. 124-131) and sugar beets (p. 132-143) The addition of SelectMax was the only change in the potato and sugar beet sections for the 2007 Weed Control Guide. SelectMax is described in the soybean section above. |
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| New herbicide options in corn and soybean David Hillger and Christy Sprague Crops & Soil Sciences Since the release of the 2007 Weed Control Guide for Field Crops, several new herbicides have been registered for the 2007 growing season in corn and soybean. Following 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 previous article, Updates from 2007 Weed Control Guide for Field Crop. Corn herbicides Breakfree, Breakfree ATZ and Breakfree ATZ Lite are a group of preemergence/early postemergence herbicides that are similar to Surpass, Keystone and Keystone LA. The use rates and restrictions for the Breakfree family of products will vary for soil conditions and this information can be found on their label. Status is a new formulation of Distinct (dicamba + diflufenzopyr) that includes a crop safener for postemergence control of broadleaves. This safener increases the metabolism of the herbicide inside the corn plant resulting in a decrease in the potential for injury due to an extreme wind event. The recommended use rate for Status alone is 5 oz/A or 2.5 oz/A if tank mixed another herbicide like glyphosate. The preferred adjuvant for Status is crop oil concentrate, however if tank mixed with an adjuvant-loaded glyphosate, no adjuvant is needed. Status can also be tank mixed with herbicides that require non-ionic surfactant or methylated seed oil adjuvants. Soybean herbicides Although Canopy EX (29.5 DG) is not a new herbicide to the soybean market, recent label changes will allow for it to be used differently that it has in the past. Canopy EX is a premixture of Classic (chlorimuron) plus Express (tribenuron) that has been typically used in the fall or early spring (45 d prior to planting) for control of winter annual weeds and residual control of certain summer annual weeds. Canopy EX can now be applied within 7 d of planting soybean if the use rate is 2.2 oz/A or less and can be applied within 14 d of planting with use rates of 2.2 to 3.3 oz/A. As with all chlorimuron products use rates and rotational restrictions are dependent on soil pH. Valor XLT 40.3DG is a new premixture being marketed by Valent Agricultural Products. Valor XLT contains Valor (flumioxazin) and Classic (chlorimuron) and can be applied in the fall, early preplant, preplant, or preemergence. The typical use rate of Valor XLT is 3 oz/A (1.76 oz/A of Valor and 1.24 oz/A of Classic), unless the soil pH is greater than 6.8. If the soil is pH ranges from 6.9 to 7.6, Valor XLT should only be applied at 2.25 oz/A or less. DO NOT use Valor XLT if soil pH is greater than 7.6. Valor XLT will provide control of some winter annual weeds and provides residual control of common lambsquarters, common ragweed, eastern black nightshade, pigweeds, smartweed, velvetleaf, wild mustard and horseweed (marestail). Valor XLT should not be applied to emerged soybeans and should not be tank-mixed with chloroacetamide containing products like: s-metolachlor (Dual Magnum), dimethenamid-P (Outlook), alachlor (Intrro), or flufenacet (Define) or severe soybean injury can occur. Rotational restrictions and precautions for Valor XLT are similar to restrictions for Valor and other chlorimuron containing products. |
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| Mark your calendars: MSU Weed Tour and Crop Diagnostic Day dates are set Christy Sprague Crop & Soil Sciences Before you schedule your vacation this summer, make sure to get these two dates on your calendar. The 2007 MSU Weed Tour will be held on Wednesday, June 27 and the Fifth annual MSU Crop Diagnostic School will be held on Tuesday, July 10. These field days offer you the latest information in weed management and other crop protection and crop management strategies. Stay tuned to future CAT Alerts for details and registration forms for each of these events. |
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| Buildup and maintenance fertilization – reducing cost Darryl Warncke Crop & Soil Sciences Good news, the price for corn, soybeans and wheat went up significantly since 2006. This is a result of the high demand for corn to produce ethanol and many other products. Corn acreage for 2007 is predicted to increase greatly, which increases the demand for fertilizer nutrients. Hence, the bad news, fertilizer prices have increased greatly, especially nitrogen. In a separate article, Dr. Gehl is addressing nitrogen fertilization of corn. This article will focus on phosphorus (P) and potassium (K) fertilization. Recommendations from MSU for P and K include; a portion to build up the soil to a critical level (CL), which corresponds closely to the soil test value where 95 percent of maximum crop yield is attained, and a portion for maintenance, which is equal to crop removal. Depending on the price ratio of the crop to the fertilizer nutrient, the CL may also be close to the point of maximum economic yield. For corn and soybeans, the CL soil test is 15 ppm P, and for wheat and alfalfa the CL value is 25 ppm. The adequate soil test P range is 15 ppm above the CL, or is 15 to 30 ppm for corn and soybean, and is 25 to 40 ppm for wheat and alfalfa. For K the CL value varies with soil texture (as indicated by the CEC, cation exchange capacity). The adequate range is 20 ppm above the CL value for most field crops. The long term goal is to maintain the P and K soil test values in the adequate range. The soil test P or K value can be maintained in the adequate range by applying an amount of phosphate or potash that is equal to what is removed in the harvested portion of the crop. Table 1 indicates the amount of P and K removed in each harvested unit for selected crops. If the soil test P or K value is below the CL value, then an additional amount is recommended to build the soil test value up to the CL value over a four-year period. If the budget is tight and choices must be made on how to spend resources for inputs, the fertilizer bill can be reduced by one of the following approaches. When the soil test value is below CL (in the buildup zone), apply only the maintenance amount of P or K. When the soil test value is in the adequate range, reducing the amount applied should not adversely affect crop yield, but will result in a decrease in the soil test level. Applying 20 lbs less P2O5/acre than crop removal may result in a decrease in the soil test P value of about 2 ppm in sandy soils, 1 ppm in loam soils and 0.5 ppm in clayey soils. For each 20 lbs K2O/acre less than crop removal applied, the soil test K may be expected to decrease about 4 ppm, 3.3 ppm and 2.8 ppm, respectively, in soils with CECs of 5, 10 and 15 me/100 grams. The following are three examples of how these approaches work. Example 1. Soil test P value is 25 ppm (adequate range), corn is being grown and the yield potential is 200 bu/acre. The maintenance recommendation is 74 lbs P2O5/acre (200 x 0.37). Applying 30 lbs P2O5/acre in a band at planting will get the crop off to a good start and reach the yield potential, and the fertilizer bill will be reduced by the cost of 44 lbs P2O5/acre (~$12/a). Example 2. Soil test P value is 10 ppm so the recommendation for 200 bu corn is 99 lbs P2O5/acre (25 for buildup and 74 for crop removal). Applying only crop removal (74 lbs P2O5/acre) will be enough to reach the yield potential and will save the cost of 25 lbs P2O5/acre (~$7/a). Example 3. Soil test K value is 30 ppm below the CL value (105 ppm) in a soil with a CEC of 12. K2O recommendation for 200 bu/a corn is 102 lbs K2O/acre (48 + 54). Applying only crop removal (54) will save the cost of 48 lbs K2O/acre (~$12/a). Table 1. Nutrient removal in harvested portion of selected crops
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| Nitrogen fertilizer additives Ron Gehl Crop & Soil Sciences The escalating prices of N fertilizers and concerns regarding N fertilizer supplies have many producers questioning the potential benefits of N fertilizer additives, particularly nitrification and urease inhibitors. Extensive research on these types of products has been conducted throughout the North Central region for many years, with results generally indicating that effectiveness is reliant on many factors, including N source, timing, soil type and tillage. In years past, a somewhat common practice was for growers to apply a little extra N as a relatively cheap form of insurance. However, with high N fertilizer cost many growers are looking for alternative strategies to assure adequate N is provided to the growing crop. The primary objective of urease inhibitors is to reduce the potential volatilization losses of urea-based fertilizers. When urea is applied to soil, it must be converted through hydrolysis (addition of water) to the ammonium form before it becomes plant available. This conversion is driven by an enzyme called urease, which is abundant within the soil. When urea is applied and incorporated or rained into the soil, the breakdown of urea to the ammonium N form will occur in about 2 to 3 days. If urea is surface applied and not incorporated within 2 to 3 days, urea can be converted first to ammonium and subsequently to ammonia, which is susceptible to volatilization loss. Nitrogen losses due to volatilization can be in excess of 20% of the applied N, and are typically the greatest where there is a relative high surface soil pH, high amounts of surface residue, and in warm and windy weather conditions. Urease inhibitors are applied to interfere with the urease enzyme, and essentially delay the hydrolysis of the urea molecule, typically for 10 to 14 days. Most university research to date has focused on the urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT), which is sold under the trade name Agrotain. Research results have indicated that NBPT can be effective at reducing volatilization losses and enhancing yields, though consistent responses should not be expected every year or on all fields. Hendrickson (1992) summarized nationwide research regarding the effects of NBPT use for surface applied urea and UAN. The summary included data from 78 experiments in 17 states (including Michigan), with 45% on no-till, 45% reduced till, and 10% on conventional tilled fields. When averaged across all sites and years, the use of NBPT increased grain yields 4.3 bu/ac when applied with urea and 1.6 bu/ac when applied with UAN. Application of NBPT resulted in yield reductions of 10 bu/ac or more in 7% of the trials. Table 1 is a summary adapted from Laboski (2006). Table 1. Summary of corn yield increases from application of NBPT with surface applied urea and UAN (Hendrickson, 1992). Yield increases were significant (P<0.01).
So where are urease inhibitors most likely to pay off? If urea or urea-based fertilizers are surface applied and not incorporated, a practice typical of no-till cropping systems, the chance for volatilization losses is most significant. Cropping systems/tillage practices that result in relatively high surface residues will promote volatilization, as will recent unincorporated lime applications. The amount of N loss through volatilization will depend on whether adequate rainfall (about 0.25”) or mechanical incorporation occurs within a few days of application. If adequate rain comes, volatilization losses will be minimized and money spent on a urease inhibitor may not be recovered in N savings and yield increases. But, if the urea is not moved into the soil soon after application, the effectiveness of the urease inhibitor will be enhanced. At about $50/gal, applied at a rate of 5 qt/T of urea, the additional cost of a urease inhibitor would be about $0.07 per pound of actual N. When deciding whether to use this type of product, growers should evaluate their cropping system and determine whether the risk of N loss is worth the extra input cost. If conditions are favorable for N loss, use of NBPT can help prevent N (and yield) losses, but positive responses should not be expected every year. Nitrification is a microbial soil process by which N in the ammonium form is converted to nitrate. Soil N as ammonium is held on soil cation exchange sites and is relatively stable, in terms of loss, while nitrate-N is highly susceptible to losses by leaching or denitrification. Leaching losses are especially pronounced in coarse textured soils that receive excess water while denitrification occurs in warm (>50◦F), wet conditions primarily on fine textured soils, though both these processes can occur on some level regardless of soil texture. When conditions are favorable for these loss mechanisms, it is desirable for N in the soil to remain in the ammonium form until the time of rapid crop demand. Nitrification inhibitors delay the conversion of ammonium to nitrate by interfering with the metabolism of Nitrosomonas bacteria. Common nitrification inhibitors include nitrapyrin (N-Serve) and dicyandiamide (DCD/Guardian), which are typically effective for 3 to 6 weeks depending on soil and climate conditions. With fall N applications (not recommended for MI), nitrification inhibitors may delay conversion to nitrate until soil temperature drop low enough (below 40◦F) to limit denitrification risks. With spring N applications, the inhibitors keep soil N in the ammonium form until peak crop demand (for corn, about the 6-8 leaf stage). As with urease inhibitors, many years of research have been conducted evaluating the effects of nitrification inhibitors on various crops and cropping systems. Work in Wisconsin with N-Serve on corn showed that when all the N was applied preplant, N-Serve resulted in increases in both yield and return. When N was applied sidedress there was no benefit to using N-Serve. The results of the study also showed improved yields and return for sidedress N applications compared with preplant application, regardless of the nitrification inhibitor. Data from the trial are shown in Table 2 adapted from Laboski (2006): Table 2. Four year average effect of N timing and N-Serve on corn yield at Hancock, WI (sandy soil) (Wolkowski, 1995; adapted from Laboski, 2006)
Calculations based on $3.50/bu corn, $0.45/lb N, and $32/gal of N-Serve. A report by Hoeft, 1984, summarizing results of research in many states, showed yield and return benefits of N-Serve for fall-applied N, but no benefit when N was applied in the spring. Results from that study also demonstrate a clear economic benefit to spring N applications compared with fall applications. (See Table 3) Table 3. Effect of time and rate of N application and N-Serve on corn yield in Illinois (Hoeft, 1984).
In general, research has shown that the use of a nitrification inhibitor is most likely to result in yield and economic returns when applied with N on coarse-textured soils or fine-textured poorly drained soils. Even when using a nitrification inhibitor, there is continued risk of N loss from the soil depending on environmental conditions and crop N uptake. But, in high loss environments the use of an inhibitor has a much greater probability of reducing N loss. Recognizing these conditions is important when making N management decisions, and will ultimately impact net return for growers. References |
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New formulation of Kocide® 3000 available for 2007
Kocide products have been used very successfully against many bacteria and diseases on fruit and vegetables. This preventative copper fungicide has also demonstrated very good activity against Septoria and powdery mildew in wheat to protect early plant health. |
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| Field crops page now available on Enviro-weather Mark Trent Enviro-weather coordinator As plans are underway to provide field crop producers with relevant weather-based plant and pest management decision making tools, Enviro-weather has developed a base page for field crop users. Currently, the page contains basic links to weather information such as; Weather summary, including temperature, degree days, and rainfall, Overnight temperatures, More weather data from MAWN for this station and National Weather Service local forecast and radar. If you have accessed this CAT Alert via the internet, click on links above to access information provided by the East Lansing MAWN station. To get these reports for the stations nearest you, just log on to Enviro-weather at www.enviro-weather.msu.edu and on the map, click on the station of your interest then click on field crops. In addition to weather information, a link is provided for Irrigation Scheduler V 4.0, an interactive irrigation scheduling tool that uses a combination of evapotranspiration data from the MAWN station nearest your field and your irrigation and rainfall data from your particular field provided by the user. More products on the way An Enviro-weather field crops workgroup is being formed to determine what useful and applicable pest and plant management products would be most useful for field crop producers in Michigan. The workgroup will be made up of interested growers, industry personnel, Extension Educators and researchers. The workgroup will also address other needs such as which educational, extension and research resources should be linked to the system. Enviro-weather tip Get your agricultural weather with a click of a button by bookmarking your favorite page on Enviro-weather. For example to get easy access to the field crops page, go to www.enviroweather.msu.edu, click on the station of you choice and click on field crops. Now that you are on the field crops page click on “Bookmarks” on your browser toolbar and click bookmark this page. The next time you need ag weather information you can click the bookmarks button and go right to Enviro-weather field crops. |
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Regional reports Weather Fertilizer is higher priced and in some cases hard to get. Grain storage has been in strong demand, especially since the ethanol plant near Blissfield is up and running. Demand for corn will be high from all grain companies. ADM Grain Company in Toledo loaded about twice as many “salties” of corn in 2006 as previously. Although the weather has generally been un-spring-like, we know that spring is here because the Detroit Red Wings and Pistons are into their playoff runs. |
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| 2 – Southwest
Weather The 2007 winter continues in southwest Michigan. Areas of the southwest received anywhere from 2 to 4 inches of wet snow overnight on April 11, and up to 5 to 12 inches over the last weekend. Couple this with snow on the ground until mid-March, and you can quickly get the picture that there has been limited opportunities for field work so far this season. However, when it was warm, it was really warm. Soil temperatures at the Mendon MAWN Station showed that following a week of very warm temperatures (65E-78EF for highs, and very warm nights), soil temperatures spiked at 55EF at the 2-inch level. On April 9, following the snow and cold weather, soil temperature was at 35.6EF. In short, we will need some good weather to move the soil temperatures back up into the 50EF window. Commodity reports Winter wheat had greened up very nicely with the warm temperatures in March. There have been some questions coming in about the effect of cold temperatures on the wheat in the region. I had the opportunity to visit with Dr. Larry Copeland, the small grain specialist emeritus with the MSU Department of Crop and Soil Sciences and Martin Nagelkirk, my colleague in Sanilac County. Both Larry and Martin suggest that wheat in the green-up and early tillering stages should be able to tolerate temperatures down to the 12EF. Dr. Copeland said that as long as the soils were not saturated or flooded, the plants should be able to withstand the temperatures that we have seen in the southwest, somewhere in the 17 to 18 degree mark for the southern portion of the region. Many areas also had a blanket of lake effect snow showers, which could also help to protect the plants from the cold winds. Alfalfa had begun to green up with the warmer temperatures as well. While the plants that harden down properly for the winter can withstand very cold temperatures, plants that have begun to grow again in the spring have less tolerance. Extended periods of temperatures below 25EF have been reported by many Midwest researchers as being able to cause tissue damage. Blackening of the tissue can indicate that tissue loss has occurred. On plants severely effected, bleached leaves may occur on new growth. Most fields in the western portion of the region had at least some snow cover to help protect the lower portion of the plants from the extreme cold. Preparations for corn and soybeans: Fieldwork has been limited primarily to fertilizer spreading to this point. |
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3 -- West Central Spring is starting out cold and wet in the west central region. In Montcalm County Thursday, April 12, we have 2-4 inches of snow on the ground with snow falling. Minimum soil temperatures as recorded at the MSU experiment farm in Entrican have been in a range of 32 to 37 degrees for the last week, 10 degrees lower than the previous week. Commodity reports Wheat broke dormancy in the last week of March with most fields showing minimal winter injury; even those that were planted in early November appear to have survived well. By in large, most stands appear to be adequate. Winter annual weeds have also broken dormancy with growth progressing slowly. Very little tillage or field work has been done to date. Only one report of some oats planted. Corn fever has taken hold. Many plan to increase corn acres in the area when and if the weather permits. |
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4 -- Central Currently, it looks more like December 12 than April 12. We are expected to get 3-6 inches of snow in Isabella County. Soil moisture is described as very adequate to saturated. Most growers are getting a little impatient with the colder wet weather, but most feel we will benefit from the soil moisture reserves over the course of the growing season. Soil temperatures were in the low forties last week. Commodity reports The wheat crop has come through winter in pretty good shape at this time. Many of the late-planted fields last fall were able to get adequate growth because of the nice fall weather. Most early nitrogen has been applied. The warm weather earlier has brought on the chickweed. Scout fields for weeds. It is a little early to tell how the alfalfa came through winter. Some fields are just breaking dormancy. A few acres of sugar beets have been planted. Field activities At this point most activities are taking place in the shop. They are fine tuning equipment that is being readied for the planting season. Farmers are ready to get into the fields, so they don’t have to watch the roller coaster grain markets on the DTN |
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| Weather news: Winter blues Jeff Andresen Agricultural Meteorology Geography Winter returned to the Great Lakes region in full force on April 4 ending almost two weeks of abnormally mild weather across the state. An intense area of low pressure moved through the state bringing a variety of weather conditions ranging from thunderstorms in southern sections to heavy snow in the north. Cold, Canadian-origin air moved in behind the storm, bringing an unusual late season lake effect snowfall event to all areas of the state. Snowfall totals by Sunday, April 8 exceeded 50 inches in some areas of the Upper Peninsula. Sub-freezing temperatures occurred in all areas of the state from April 4-8, with low temperatures falling into the teens and 20's in the south to as low as -5EF in sections of the Upper Peninsula. A second winter storm impacted the state on April 11-12, bringing more heavy snow and strong winds to all but southeastern sections of the state. There is some better news looking ahead. A gradual moderating trend is expected, although mean temperatures will likely remain at near to below normal levels into the upcoming week. Following a dry day statewide on Friday, April 13, an area of low pressure will move through sections of the Ohio Valley on Saturday, April 14, bringing the chance for some light rain or snow. In contrast to the past couple of events, however, precipitation coverage and amounts will be limited at best, with many locations remaining dry. Dry weather is also expected for at least the first half of next week. Daytime temperatures will slowly recover back to the 40's to low 50's and low temperatures into the upper 20's and 30's by Monday, April 16, with a range from the low 50's north to the upper 50's south expected by Wednesday, April 18 of next week. In the medium range time frame, forecast guidance suggests a less active, west to east zonal jet stream pattern across the U.S. The official NOAA 6-10 day and 8-14 day outlooks (covering April 17-21 and April 19-25, respectively) both call for warming temperatures, with a range from near normal across Lower Michigan to above normal in Upper Michigan expected, and for below normal levels state and region wide. |
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