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Agronomic Crops Network

Ohio State University Extension


C.O.R.N. Newsletter: 2021-03

  1. Ag Tech Tuesday Webinars Highlight 2020 eFields Results

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    The Ohio State Digital Ag Team’s Ag Tech Tuesday webinars are continuing this month! The online February series will cover results from several 2020 eFields trials and be held each Tuesday starting at 10:00 EST for 1 hour. There will be plenty of time for participants to ask questions.  The following provides details for the 2021 Ag Tech Tuesday sessions.


    • February 2 - Improving Profitability in Corn Production

    Weather and Climate Trends, Aaron Wilson

    Irrigation, Amanda Douridas and Will Hamman

    Corn Seeding Rates, Chris Zoller

    SmartFirmer Seeding Rate, Elizabeth Hawkins

    • February 9Pushing Soybean Productivity in Ohio

    Boots on the Ground, Laura Lindsey

    Local Boots on the Ground Results, Mary Griffith

    Foliar Fertilizer, James Morris

    Soybean Seeding Rates, Ken Ford

    Sulfur on Soybeans, John Barker

    • February 16 - Tech to Improve On-Farm Efficiency

    Manure On-the-Go Sensing, Chris Shoup

    Yield Monitor Data, Alysa Gauci

    Virtual Reality and Field Demonstrations, Brooke Beam

    Equipment Technology, Andrew Klopfenstein

    • February 23eFields Small Grains, Forages, Soil Health, and Water Quality Results

    Production Budgets and Custom Rates, Barry Ward

    Winter Annual Forages, Jason Hartschuh

    Barley Cohort, Eric Richer

    Hemp, Lee Beers

    Soil Health Testing, Boden Fisher

    Registration for Ag Tech Tuesdays is free but required.  Just visit to register.  If you have any questions, please contact Elizabeth Hawkins (

  2. Soil Health Webinar Focuses on Cover Crop Management


    The February 4th session of the webinar series The Dirt on Soil Health: Investing Below the Surface will focus on cover crop management. Dr. Hans Kok will begin by reviewing important management considerations for planting and establishing successful cover crop stands. Dr. Kok is an independent consultant based out of Indianapolis and project director with the Conservation Technology Information Center, as well as the lead agronomist for the Indiana In-Field Advantage Network. Eric Niemeyer will join Dr. Kok for the Q&A session. Eric is a Delaware County farmer who has been planting cover crops on his entire farm since 2014.

    The session is free to attend, and begins at 8:00am EST on Thursday, February 4th. 0.5 SW CCA CEUs are available for attending the live session. Register at

    This is the fourth session of a series focused on practical steps to improve soil health on-farm. Recordings of past presentations in this series are available online here.


  3. Corn College and Soybean School

    The Agronomic Crops Team will host a virtual Corn College and Soybean School on February 11, 2021. Corn College is in the morning, from 9:00 – 12:00pm, with Soybean School in the afternoon from 1:00-4:00pm. Each program will feature updates from OSU Specialists. CCA CEUs are available. The schedule for the day is as follows:

    Corn College, 9:00am-12:00pm

    • Corn Management for 2021, Peter Thomison, 1.0 CM CCA CEUs
    • Meeting Nutrient Needs in Corn, Steve Culman, 1.0 NM CCA CEUs
    • Disease Management, Pierce Paul, 1.0 PM CCA CEUs
    • Insect Management, Andy Michel, 1.0 PM CCA CEUs

    Soybean School, 1:00-4:00pm

    • Soybean Management for 2021, Laura Lindsey, 1.0 CM CCA CEUs
    • Weed Management, Mark Loux, 1.0 PM CCA CEUs
    • Disease Management, Anne Dorrance, 1.0 PM CCA CEUs
    • Insect Management, Kelley Tilmon, 1.0 PM CCA CEUs

    This program is free to attend. Register at

  4. Upcoming Cold Temperatures and Winter Wheat

    The upcoming forecast of cold temperatures has sparked some concern about damage to the winter wheat crop.

    Fortunately, winter wheat is very resistant to cold temperatures during the months of December, January, and February when the plant is dormant. During these months, winter wheat can withstand below freezing temperatures, especially when there is snow cover. In early 2019, Ohio experienced polar vortex temperatures without snow cover. However, no (or minimal) damage was observed in winter wheat (Figure 1).

    Figure 1. Polar vortex temperatures with no snow cover in early 2019 resulted in survival of winter wheat.

    Besides wheat’s natural ability to be resistant to cold temperatures, plant breeders have developed wheat varieties that are adapted to Ohio’s environments. Occasionally some companies have tried to push North varieties adapted to the Mid-Atlantic region that may be affected by extreme cold. However, most often wheat that has not survived cold temperatures was planted too late for adequate growth, planted too shallow to protect the crown, or too much water on low spots before the cold temperatures.


  5. Herbicide Resistance in Ohio Waterhemp Populations

    Author(s): Mark Loux

    Waterhemp populations across the Midwest continue to develop more complex variations of herbicide resistance.  Multiple resistance to an increasing number of herbicide sites of action is the norm in many populations in states west of Ohio.  Waterhemp has on the whole developed resistance to seven sites of action, including the following:

    Group 2 – ALS inhibitors – chlorimuron, imazethapyr, etc

    Group 4 – Synthetic auxins – 2,4-D, dicamba, etc

    Group 5 – Photosystem II inhibitors – atrazine, metribuzin, etc

    Group 9 – EPSP synthase inhibitor – glyphosate

    Group 14 – PPO inhibitors – fomesafen, flumioxazin, sulfentrazone, etc

    Group 15 – long chain fatty acid inhibitors – metolachlor, pyroxasulfone, etc

    Group 27 – HPPD inhibitors – mesotrione, isoxaflutole, topramezone, etc

    Individual populations with resistance to three or more sites of action are common.  Mutations are occurring that confer resistance to several of these sites of action simultaneously, through a resistance mechanism that enhances the metabolism and inactivation of the herbicides by the plant.  For example, there appears to be a linkage in the resistance to mesotrione and atrazine, where resistance to one means it’s likely that resistance to the other occurs also.  Weed scientists have concluded that this weed is capable of developing resistance to any herbicide site of action used against it.  We aren’t actually sure what the correct recommendation is for stewardship of herbicides once a single mutation can confer resistance to multiple sites of action.  Which is the reason we stress the need to take steps in mid to late season to prevent seed from plants that survive management strategies. 

    Since 2016, OSU weed scientists have been taking steps to maintain a rough assessment of the herbicide resistance characteristics of Ohio waterhemp populations. Some of these populations were randomly collected during our surveys and some provided to us by OSU Extension Educators or clientele.  For the first several years we focused on the possible resistance to glyphosate and group 14 herbicides.  Essentially all waterhemp populations are resistant to group 2 herbicides so there isn’t any point in looking for it – it’s assumed.  

    2016 – 18 populations

    Glyphosate – 100% resistant, group 14 (fomesafen) – 28% resistant

    Glyphosate + group 14 – 28% resistant

    Some populations resistant to low rate of atrazine (but not metribuzin)

    2017 – 13 populations collected in fields from plants surviving group 14 herbicides

    77% of the populations were resistant to group 14 herbicides (did not test for glyphosate)

    2018 – 8 populations

    Glyphosate – 87% resistant, group 14 (fomesafen) – 25 to 50% (rate-dependent)

    Glyphosate + group 14 – 25 to 50% resistant (rate-dependent for group 14)

    Starting with 2019 populations, we have expanded to assess response of waterhemp populations to foliar applications of 2,4-D, and groups 5 (atrazine), 14 (fomesafen), and 27 (mesotrione).  Our assumption at this point is that most waterhemp populations are glyphosate-resistant so there’s point in looking for it.  We assessed response of 19 populations collected in 2019, and the results below show assessment of % mortality from each herbicide/rate combination.  (1X and 4X indicate a use rate and four times that rate).



    >80% dead

    Partial resistance

    50 to 80% dead


    <50% dead


    -------  % of populations -------

    Atrazine - 1.5 lb ai




    Atrazine - 4 lb ai




    Mesotrione – 0.09 lb ai




    Mesotrione – 0.37 lb ai




    2,4-D - 1 lb ai




    2,4-D – 4 lb ai




    Fomesafen – 0.3 lb ai




    Fomesafen – 1.2 lb ai




    We are also conducting soil-applied screens for group 15 herbicides (s-metolachlor).  In the table below, assessment at 14 and 28 days after preemergence treatment was based on % control compared with a nontreated for each population. 


    >80% control

    50 to 80% control

    <50% control


    -------  % of populations -------

    14 days




    1.5 lb ai




    4 lb ai




    28 days




    1 lb ai




    4 lb ai




    Some observations on these data:

    - Herbicides do not necessarily work the same in the field versus the greenhouse, so results can vary between them for a given rate.  It’s evident here that the 1X rate of the 2,4-D and S-metolachlor were possibly not truly a use rate in the greenhouse.  This doesn’t change the fact that there was variable response among populations.

    - Overall, the data show that Ohio waterhemp populations vary in their sensitivity to these herbicides.  For all of the herbicides, at least some populations were resistant to the 1X rate and partially resistant to the 4X rate.  We assume this is an evolved lack of response that is developing over time in some fields in response to the use of these herbicides, and also movement of seed from field to field.  We expect this to happen, based on the history of resistance in areas west of us with a longer history of waterhemp resistance problems.

    - There could not really have been much selection by 2,4-D in these fields prior to 2019, based on the Enlist soybean adoption timeline.  So the lack of response of some populations to this herbicide may be due to a mechanism that confers resistance to multiple sites of action.  A population from Illinois was identified several years ago where on mutation conferred resistance to atrazine, mesotrione and 2,4-D.

    - Some populations were completely sensitive to all of these herbicides, and other populations had a reduced response to all.  In one Darke County population, mortality from foliar applied herbicides did not exceed 60% at the 1X rate, and ranged from 77 to 96% at a 4X rate.  Control from S-metolachlor did not exceed 60%.  Darke County is one of the counties with the longest history of waterhemp issues, so selection for resistance has occurred for a while.  But – another Darke County population was still sensitive to all herbicides.

    - The populations tested are a composite sample from several plants at a field site, so we assume that where some degree of resistance occurs, there are individual plants that may be mostly resistant and others that are still susceptible. 

    We are in the process of screening populations collected in 2020.  We are also part of a regional project that screens waterhemp populations from various states for resistance to glufosinate and dicamba.  So far, that project has not identified resistance to either herbicide in the populations sampled from any state, although dicamba resistance has independently been confirmed in other non-Ohio waterhemp populations. 

    Additional resources

    Herbicide resistance in Ohio waterhemp populations (youtube video)

    PDF of Powerpoint used in video



  6. Fertility Calculator for Ohio Recommendations - Version Update

     An update to the Fertilizer Calculator for Ohio has been posted at The Fertilizer Calculator for Ohio (Version 2021) corrects an error in calculating whole field fertilizer cost and standardizes the width of field/subfield description fields across tool forms based on user feedback.

    The tool is a Microsoft Excel spreadsheet developed to support users who want to generate their own recommendations based on the Tri-State Fertilizer Recommendations for Corn, Soybeans, Wheat, and Alfalfa, 2020. The spreadsheet is designed to be compatible with Excel version 1997-2003 or later.

    Recommendations can be generated for the following crops:

    1. Corn
    2. Corn-Silage
    3. Soybeans
    4. Wheat (Grain Only)
    5. Wheat (Grain & Straw)
    6. Alfalfa
    7. Grass Hay
    8. Grass/Legume Hay

    Spreadsheet features:

    • There are 21 data lines.
    • Supports copying data soil test data from another spreadsheet or within the spreadsheet.
    • User controls whether recommendations are build/maintenance or maintenance only for phosphorus (P) and potassium (K).
    • User can select appropriate critical levels for corn/soybean rotations or wheat, alfalfa, or grass legume hay rotations for P recommendations.
    • Can select a shorter or longer buildup period than standard 4 year for P & K.
    • Total fertility needs can be determined for a 1-, 2- or 3-year application on P & K Recommendation page.
    • User can compare cost of two lime sources on lime recommendation page.
    • User can determine total cost of lime needed in the recommendation developed.
    • User can determine total cost of P & K fertilizer needed to meet the nutrient recommendation.

    The spreadsheet is available at:

    A printed User Guide is available at:

    A video demonstration at:

  7. Crop Diversification to Improve Your Bottom Line

    The Ohio State University Agronomy Team’s Alternative Crops Committee has planned 3 educational opportunities looking at the subject of “Increasing Your Crop Diversity to Improve Your Bottom Line.” The first of these 3 meetings has already occurred on January 14, 2021.  Its subject was Getting Started with Specialty Small Grains. The recordings of the presentations are available here. The second and third sessions are scheduled for February 4 and March 4, 2021.

    The topic for this Thursday’s (2/4/2021) meeting is “Getting Started with Seed Production.” We have two speakers for the morning meeting that starts at 9:00 a.m., Fred Pond of Pond Seed Company, Scott, Ohio. He will discuss the seed production requirements that are over and above the normal production practices for producing an agronomic crop for standard consumption.  And Carl Stuck, a diversified farmer in western Ohio with experience in producing cover crops for seed. He will discuss major cover crops for use in Ohio, basics of seed production and cleaning, and how to get started.

    The March 4, 2021 topic is “Getting Started with Non-GMO Crops.” This session starts at 9:00 a.m. as well.  There are 3 presentations that day covering Production Practices, Insects: The Forgotten Corn Pests, and Weed Control in Non-GMO crops.

    To register for these last two sessions, go to: and

  8. Conservation Tillage and Technology Conference Will Be Virtual

    Author(s): Mark Badertscher

    You won’t want to miss this year’s Conservation Tillage & Technology Conference (CTC).  The annual conference, which is normally held on the campus of Ohio Northern University in Ada will be virtual this year. Four days of topic related programming will be provided March 9-12, 2021 (Tuesday-Friday). You’ll need to furnish your own snacks during the scheduled breaks.

    Each day will start at 8:00 a.m. (EST) and will have 5 hours of great value, ending about 2:00 p.m. That adds up to 20 hours of presentations on current topics important for farmers, crop consultants, and educators. Because the program is virtual and therefore travel is not an issue, the planning committee has put together a list of national experts from universities, agencies, industry professionals, and others.

    All 20 hours qualify for CCA credits. At least 5 to 10 hours will qualify for CLM credits. Registration is $50. That gives you access to the entire Virtual CTC 2021. Check out the full Program schedule and Registration details at: All from the comfort of your warm office or favorite chair.

    Topics for each of the four days, March 9-12 (Tuesday-Friday) are:

    • Tuesday-Crop Management; 
    • Wednesday-Nutrient Management; 
    • Thursday-Pest Management; 
    • and Friday-Soil & Water Management.

    Registration is now open and don’t forget to mark your calendar.

  9. Spraying Done Right!

    This 1-hour long Zoom webinar, on February 4th at noon, is meant for growers, and for people who assist them; especially pest management advisors and pesticide applicators. The event will host top-notch experts in the fields of herbicide science, plant pathology, atmospheric sciences and agricultural regulation.

      This webinar will deal with pesticide application in agriculture, from the following perspectives: 

    * Damages to crops, due to pesticide and herbicide drift from neighboring fields.

    * Inefficiency in pesticide application, and ways to correct it.

    * Pesticide drift liability: perspectives and lessons to recipients and to sources; growers and pesticide applicators.

    * Meteorological factors affecting pesticide application, and localized weather forecasting. 

    List of speakers:

    Prof. Doug Doohan (Herbicide Science), Department of Horticulture and Crop Science, Ohio State University.

    Prof. Dorita Edelstein (Atmospheric Science), Institute of Earth Sciences, The Hebrew University of Jerusalem and the Israel Institute for Biological Research.

    John Fentis, Esq. (Law), Environmental Director, California District Attorneys Association.


    Dr. Nadav Nitzan, Head of Plant Pathology, Valley of Springs Research Center, Israel (formerly of the Department of Plant Pathology, Washington State University).

    Register for free here:


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.


Andrew Holden (Resigned Educator, Agriculture and Natural Resources)
Andy Michel (State Specialist, Entomology)
Ann Chanon (Educator, Agriculture and Natural Resources)
Barry Ward (Program Leader)
Clint Schroeder (Program Manager)
David Marrison (Educator, Agriculture and Natural Resources)
Eric Richer, CCA (Field Specialist, Farm Management)
Gigi Neal (Educator, Agriculture and Natural Resources)
Glen Arnold, CCA (Field Specialist, Manure Nutrient Management )
Hallie Williams (Educator, Agriculture and Natural Resources)
Jason Hartschuh, CCA (Field Specialist, Dairy & Precision Livestock)
Lee Beers, CCA (Educator, Agriculture and Natural Resources)
Les Ober, CCA (Educator, Agriculture and Natural Resources)
Mike Estadt (Educator, Agriculture and Natural Resources)
Nick Eckel (Educator, Agriculture and Natural Resources)
Rich Minyo (Research Specialist)
Richard Purdin (Educator, Agriculture and Natural Resources)
Sam Custer (Educator, Agriculture and Natural Resources)
Sarah Noggle (Educator, Agriculture and Natural Resources)
Steve Culman (State Specialist, Soil Fertility)
Ted Wiseman (Educator, Agriculture and Natural Resources)
Tony Nye (Educator, Agriculture and Natural Resources)
Trevor Corboy (Educator, Agriculture and Natural Resources)
Wayne Dellinger, CCA (Educator, Agriculture and Natural Resources)


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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