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C.O.R.N. Newsletter: 2016-27

  1. Drought Stressed Corn as Silage

    Author(s):

    Rain has been spotty across much of Ohio this summer and there are areas where corn was under moisture stress during the critical pollination period.  As a result, this drought stressed corn has poor grain development and small cobs.  Much of this corn may end up chopped for corn silage.  Typically the most frequent questions about using drought stressed corn for corn silage revolve around nitrate toxicity, expected yield and quality.

                In the August 16 issue of the CORN newsletter (https://agcrops.osu.edu/newsletter/corn-newsletter/potential-nitrate-problems-drought-stressed-corn) Peter Thomison and Laura Lindsey addressed the question of potential nitrate problems in drought stressed corn.  When drought occurs during or immediately after pollination it raises the flag of potential nitrate accumulation.  In drought conditions nitrates accumulate in the stalk of the plant, with the lower portion of the stalk having the highest concentration of nitrates.  High and potentially toxic levels of nitrates are more likely to accumulate if high rates of nitrogen fertilizer or high rates of manure were applied to the crop.  Testing for nitrates before chopping may be advisable in those conditions.  If nitrate levels are high, raising the chopping height to 10-12 inches can be helpful, but obviously tonnage is going to suffer.  If the nitrate accumulation is borderline high, then it probably is not necessary to raise chopping height because nitrate concentrations are reduced during the ensiling process, according to some sources, as much as one-third to one half of the nitrates may be converted to nitrous oxide compounds which leave the silage as a gas.  Be aware that this gas, typically a yellow-brown in coloration, is very toxic and extreme care with regard to both people and animals should be taken.  Vacate the area immediately if a cloud of this gas is observed.

    Typically drought stress affects yield more than it affects the quality of corn silage.  A University of Wisconsin Agronomy Advice publication from August 2007 compared corn silage yield and quality factors across 4 locations from 2003 through 2006.  Each location had at least one drought year during that time frame and some locations had 2 drought years.  When drought stress extended into the pollination period, similar to what we have experienced in some of our fields this year, the silage yield was reduced by 18 to 46% compared to non-drought years.  To estimate yield potential use this procedure:

    • Measure a distance equal to 1/1000th of an acre along one row and count the number of plants that will produce an ear.  This number multiplied by 1000 equals the ears per acre. For 30 inch rows this distance is 17 feet 5 inches. Repeat this at several locations within the field and take an average to get ears/acre.
    • Pick two ears at random from each measured area.  Count the number of rows and the number of kernels per row on each ear.  Get an average from all the areas measured.  Multiply the average number of rows by the average number of kernels/row.  This gives you the average kernels/ear in the field.
    • Multiply the average kernels/ear by the average ears/acre.  This gives you kernels/acre.  Typically there are about 90,000 kernels/bushel in normal corn but drought stressed corn has smaller lighter kernels.   Therefore take your kernels/acre figure and divide it by 100,000.  This will give you an estimate of bushels/acre.
    • A thumb rule for drought stressed corn is one ton of 30% dry matter silage for each 5 bushels of grain/acre.

    Quality wise, according to a Penn State publication entitled “Managing Drought Stressed Corn” drought stressed corn silage as compared to normal corn silage may be higher in crude protein, lower in starch and energy, higher in fiber content, but often with higher digestibility of that fiber.  Quality analyses presented in that publication showed drought stressed corn silage CP values ranging from 0.6 to more than 2 percentage units higher than normal corn silage, starch values were around 17% lower, energy as measured by net energy for lactation around 10% lower and NDF fiber values approximately 7% higher.

                Regardless of whether drought stressed or normal corn is being harvested as corn silage there are a few key management practices that need to be followed to make good quality silage.  The first and foremost is chop at the correct moisture concentration.  If you don’t get this right, nothing else you do is likely to improve the situation.  Optimum moisture range for bunker silos is 65 to 70%, for silage bags and for upright silos 62 to 68%.  The microwave oven method is still one of the quickest, least expensive and easiest methods of moisture determination available.  It involves collecting at least 4-6 representative corn stalks and chopping or cutting them into short lengths of less than 1 inch.  Mix well and collect a representative sample from the total.  Weigh out100 to 200 grams and spread it out on a microwave safe plate.  Heat the sample for a minute and re-weigh.  Shake and re-distribute the sample on the plate and heat for another 45 seconds to one minute.  Repeat this heating and re-weighing process until the sample stabilizes and does not decrease in weight between cycles.  Be careful as you approach the end point to avoid charring or burning the sample and adjust heating times accordingly.  The moisture content is equal to the beginning weight minus the end weight divided by the beginning weight. 
                Other key management practices to insure good quality silage include:

    • Chop at correct particle length.   The theoretical length of cut (TLC) for processed corn silage is ¾ inch and if not processed the TLC should be ¼ to ½ inch.  Drought-stressed corn has lower grain content and so will be less responsive to kernel processing.
    • Use a proven inoculant.  Severely drought stressed corn may have a high concentration of sugars which can result in increased spoilage at feed out.  The buchneri inoculants are used to increase the aerobic stability of silage during feed out and could be very cost effective when used with drought stressed corn silage. Pack, pack, pack.  Remove as much air as possible to create a favorable anaerobic environment. The guideline for packing is 800 pounds of packing weight for each ton of silage delivered to the silo or pile.
    • Cover.  This should be done as soon as the bunker is filled and the final packing had been done.  Covering prevents oxygen from getting into the silage pack.  Covering reduces DM and spoilage losses.  University research trials have demonstrated that the oxygen barrier 2-step products have reduced losses more than covering with the 6 to 8 mil plastic.

    References:

    Dorn, Thomas; Anderson, Bruce; Rasby, Richard.  The Use and Pricing of Drought-Stressed Corn.  University of Nebraska publication G1865.

    Lauer, Joe.  Drought Stress Reduces Corn Silage Yield More Than Quality.  University of Wisconsin Agronomy Advice publication.  August 2007.

    Ramirez, Hugo.  Key Points to Make a High Quality Corn Silage.  Iowa State University Extension.

    Roth, Gregory.  Managing Drought Stressed Corn.  Penn State Extension publication.

    Weiss, Bill.  Making Corn Silage in Drought Conditions.  The Ohio State University, Department of Animal Sciences.

  2. Buying LibertyLink soybean seed for next year?...Things to know

    Author(s): Mark Loux

    Continued problems with marestail and ragweeds this year have a number of growers considering the switch to LibertyLink soybeans for 2017.  The LibertyLink system can certainly be a good choice for management of glyphosate-resistant populations of these weeds, along with waterhemp and Palmer amaranth.  It’s essential to use the appropriate approach to LibertyLink soybeans to get the most out of it and avoid potential problems.   Some things to consider as you make seed-buying decisions and think about your herbicide costs for next year (note – this is a recap of a March 7 C.O.R.N. article that has more detail):

    - The active ingredient in Liberty – glufosinate – is available in a number of products now.  The glufosinate products that are listed in this year’s weed control guide, Liberty, Cheetah, and Interline, have similar loading, rates, and labels.  There is also a premix of glufosinate and fomesafen, Cheetah Max, that could be helpful for bigger ragweeds or waterhemp. 

    - POST glufosinate applications in LibertyLink soybeans should be part of an overall comprehensive herbicide program that includes a preplant herbicide treatment containing effective burndown herbicides and broad-spectrum residual herbicides.  Do not shortcut the burndown program on marestail and other weeds and expect the POST glufosinate treatments to clean up a less than weed-free start.  The POST glufosinate should be targeted for weeds that eventually emerge through the residual herbicides.  Also – avoid use of glufosinate in the burndown treatment, since this can limit how much glufosinate can ultimately be applied POST.

    - Omitting residual herbicides from LiberyLink soybeans is generally a good way to ensure problems.  Any number of residual premix products can fit into the LibertyLink system.  Glufosinate can be weak on lambsquarters, larger pigweed species (including waterhemp and Palmer), and certain grasses - yellow foxtail and barnyardgrass.  The residual herbicides should cover these broadleaf weeds for sure, which is not a problem for most premix products.  Residual activity on ragweeds and marestail is also desirable.  With regard to marestail, our current recommendations for Roundup Ready soybeans are to use several non-ALS herbicides and higher rates, with the goal of not having to treat marestail POST.  It’s probably not necessary to go to extremes on the residual program in LibertyLink, since the POST glufosinate can control later-emerging marestail. 

    - Avoiding problems with POST grass control in LibertyLink soybeans can be achieved in one of two ways: 1) use a residual herbicide premix with substantial activity on annual grasses; or 2) include a grass herbicides such as clethodim or Fusion in the POST glufosinate application.  The latter approach may be most cost-effective and will also control volunteer corn, which often is not adequately controlled by glufosinate alone.  This has become a routine practice for some growers and dealers to ensure effective grass control.

    - Use of comprehensive residual herbicides usually creates a situation where one POST application of glufosinate is sufficient on many weeds.  One exception is giant ragweed, which is best managed with two POST applications – the first when ragweed is 4 to 10 inches tall, and the second about three weeks later.  Unless the ragweed population is very low, trying to get by with one glufosinate POST application will mean having to treat large plants that glufosinate can fail to control, which then regrow into late-season.  Our research with giant ragweed clearly shows that the best approach for reducing populations is to bite the bullet and make two POST applications for several years (in rotation with an effective corn program), after which it may be possible to make one application work.

    - POST application timing on waterhemp and Palmer amaranth is also an issue.  For these weeds, the preplant residual herbicides should have substantial activity, and the POST glufosinate should be applied to small plants – less than 4 inches tall.  A residual herbicide such as Zidua, metolachor, or Warrant can be included with the POST to minimize the need for a second POST application.

    - Glufosinate is a contact herbicide, and it’s essential to optimize the application parameters to ensure maximum activity.  Labels specify a minimum application volume of 15 gpa, and some applicators have found 20 gpa to be more effective.  Nozzle and adjuvant selection should be geared toward production of primarily medium-sized droplets, avoiding a nozzle droplet distribution that is biased too much toward fine or large droplets.  Applying in volumes too low is another good way to have problems with the LibertyLink system.

    -  Glufosinate activity can be reduced in cool, cloudy conditions, and there can be a need to base application decisions on weather.  Many applicators try to apply primarily during periods of relatively warm and sunny weather to avoid performance problems.  Using enough residual herbicide should result in enough flexibility in the POST application window to manage weather issues.

     

  3. Warmer and Drier Weather Returning to Ohio in September

    Author(s):

    August continued the warmer than normal trend. However, Ohio did get some beneficial rain which helped some. June to August will go down as about 2-3 degrees above normal and precipitation 60-100% of normal (below) north half of Ohio and 100-125% of normal (slightly above) in the south half. It was the tails to two states that can be seen in the graphics attached form the Midwest Regional Climate Center.

    As discussed a few weeks ago, it looks like the helpful rain in many areas was a pause in a preferred warmer and drier than normal pattern. All indications are September will be warmer and drier than normal for much of the state. It may turn wetter again toward the end of September.

    September will start the first few days with a fall-like shot of cooler air with lows mostly in the 50s and highs in the 70s. A few upper 40s in low lying areas later this week can't be ruled out but 80s will return quickly by this weekend into next week with a few highs in southern areas near 90.

    The NOAA/NWS outlook for first half of September in the attached graphics shows the warm and drier weather. Temperatures will respond 3-5F above normal with a few days being at least 10F above normal in September.

  4. Cover Crop Field Day

    Cover crops can help protect soil erosion, keep nutrients in place and build valuable organic matter. Many farmers have questions on species selection and management strategies. On September 8, spend the day with cover experts and farmers using cover crops at a Cover Crop Field Day in Urbana.

    Sarah Noggle, OSU Extension Paulding County, will talk about cover crop selection and how the Midwest Cover Crop Council’s selection tool can be used to assist in deciding which covers are best for individual farms. George Derringer is a soil scientist with NRCS and will cover soil health topics and how cover crops play a role in promoting soil health. Learn from experienced farmers during a panel session where they will discuss their cover crops uses and answer questions from attendees.

    The afternoon will be spent exploring a local farm where different varieties of cover crops are growing. We will explore the soil structure and see a planting demonstration. Farmers are invited to bring soil samples for a slake test. These samples need to be the size of a tennis ball and dried for a week. Certified Crop Advisor credits offered include 4.5 Soil and Water and 0.5 Nutrient Management. Four hours of Certified Livestock Manager credits will be offered as well.

    Registration is due by 9/5 and is $20/person. This includes lunch and materials. A registration flyer can be found at http://go.osu.edu/agevents . Questions can be directed to Amanda at Douridas.9@osu.edu or 937-484-1526. The event will begin in the Champaign County Community Center Auditorium, 1512 South US Hwy 68, Urbana.

  5. Reminder for Two pre-FSR Events September 13 & September 14

    The first is the FSR Agronomy College will be held with the partnership of OABA and OSU Extension on September 13th. For agronomists, CCAs and custom applicators, the program will bring industry experts, OSU researchers, and agronomy service providers together to learn at the Molly Caren Agricultural Center in London, Ohio.

    • The full-day event features time with OSU Extension educators in the field at the small plot agronomy demonstrations. For the larger field demonstrations there will be topics including tip selection for the new herbicide tolerant crops, precision application, remote crop sensing, and an update on nutrient management issues in Ohio. 
    • Registration for the Agronomy College is $120 per participant. The event runs from 9 a.m. to 4 p.m., with on-site welcome and registration beginning at 8:30 a.m. To register or for more information, visit http://oaba.net/events, call 614-326-7520 or email mlong@oaba.net.

    Second is the FSR Nutrient Management Field Day on September 14th targeting farmers who need the Ohio Fertilizer Applicator Certificate.

    • Start at 9 a.m. and go until 3 p.m. This field day is a great way to learn about nutrient management concerns and solutions, but avoid a “lecture”.
    • Cost is $15 per person for the program and includes lunch. Register in advance for the program at https://www.regonline.com/fsrnmfd

    The location for both events is the general parking lot of the Farm Science Review at 445 US 40, London, OH 43140, this is a green grassy area just on the east side of the exhibit grounds – watch for signs. Both events provide CCA CEUs as well.

    For more information on either event, contact: Harold Watters, OSU Extension, watters.35@osu.edu, 937 604-2415.

Crop Observation and Recommendation Network

C.O.R.N. Newsletter is a summary of crop observations, related information, and appropriate recommendations for Ohio crop producers and industry. C.O.R.N. Newsletter is produced by the Ohio State University Extension Agronomy Team, state specialists at The Ohio State University and the Ohio Agricultural Research and Development Center (OARDC). C.O.R.N. Newsletter questions are directed to Extension and OARDC state specialists and associates at Ohio State.

Contributors

Amanda Douridas, CCA (Educator, Agriculture and Natural Resources)
Andy Michel (State Specialist, Entomology)
Anne Dorrance (State Specialist, Soybean Diseases)
Bruce Clevenger, CCA (Field Specialist, Farm Management)
Ed Lentz, CCA (Educator, Agriculture and Natural Resources)
Eric Richer, CCA (Field Specialist, Farm Management)
Glen Arnold, CCA (Field Specialist, Manure Nutrient Management )
Les Ober, CCA (Educator, Agriculture and Natural Resources)
Mark Badertscher (Educator, Agriculture and Natural Resources)
Mike Gastier, CCA (Educator, Agriculture and Natural Resources)
Pierce Paul (State Specialist, Corn and Wheat Diseases)
Sam Custer (Educator, Agriculture and Natural Resources)
Sarah Noggle (Educator, Agriculture and Natural Resources)
Steve Culman (State Specialist, Soil Fertility)
Wayne Dellinger, CCA (Educator, Agriculture and Natural Resources)

Disclaimer

The information presented here, along with any trade names used, is supplied with the understanding that no discrimination is intended and no endorsement is made by Ohio State University Extension is implied. Although every attempt is made to produce information that is complete, timely, and accurate, the pesticide user bears responsibility of consulting the pesticide label and adhering to those directions.

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