C.O.R.N. to go… – 2020 Weed Survey Results

C.O.R.N. to go….

A Supplement to the OSU Extension Agronomic Crops Team Online C.O.R.N. Newsletter ~ This version for Ohio’s Country Journal is by Harold Watters


Weed management in Ohio. Maybe we are getting better?

Our OSU Extension AgNR educators have been conducting fall weed surveys in Ohio soybean fields since 2006. That was about ten years after the introduction of Roundup Ready soybeans and we were starting to see break throughs and wanted to document those occurrences.


We again observed soybean fields across the state this fall to see what was out there during our annual fall soybean weed survey. We each drive about 80 miles around our county and rank weed control on a 1 to 3 scale – with a 1 a very few weeds and a 3 a trashy mess. We also count the number of weed free fields.


Statewide our most frequently observed weed was again Marestail as has been regularly since 2006 I believe; present in 21% of the fields. Giant ragweed is right there with it at 20%. Waterhemp is again a problem, even THE major problem, in some areas of the state. The count put us at 41% of the fields were weed free, up significantly from last year’s 29%. Generally, for 2020 the county folks said, “wow, it sure is clean out there”.


I also split the state into regions to see if maybe some were worse off than others. This is shown in Table 1, as well as the top five weeds for the state. Some areas had other significant weeds, you will hear more about those when you attend your pesticide recertification training this winter or attend your regional agronomy day.


Table 1. The table below shows the number of fields observed in each region, average field size, the top five weeds observed and percent of fields weed free for 2020, with 2019 for comparison.

Ohio Region # counties # Fields & size Marestail Giant ragweed Volunteer corn Giant foxtail/grass Waterhemp 2020                                  weed free fields 2019                                  weed free fields
Central 3 count 280 50 39 21 29 0
average 55.8 1.6 1.4 1.2 1.4
% of fields 18% 14% 8% 10% 0% 49% NA
East Central 2 count 159 46 23 17 15 2
average 36.4 1.6 1.5 1.1 1.1 1.0
% of fields 29% 14% 11% 9% 1% 52% 29%
North Central 1 count 83 21 2 7 9 0
average 70.3 1.3 1.0 1.0 1.2
% of fields 25% 2% 8% 11% 0% 52% 25%
Northeast 3 count 269 79 4 33 31 0
average 24.1 1.6 1.0 1.3 1.9
% of fields 29% 1% 12% 12% 0% 45% 25%
Northwest 8 count 777 200 182 89 78 111
average 69.7 1.8 1.7 1.6 1.5 1.6
% of fields 26% 23% 11% 10% 14% 37% 26%
South Central 2 count 101 19 21 4 9 17
average 32.9 1.8 1.6 1.8 1.4 1.9
% of fields 19% 21% 4% 9% 17% 32% NA
Southwest 4 count 354 40 91 63 26 10
average 70.7 1.5 1.5 1.4 1.5 1.3
% of fields 11% 26% 18% 7% 3% 47% 44%
West Central 7 count 631 91 179 115 42 154
average 53.7 1.4 1.3 1.3 1.2 1.5
% of fields 14% 28% 18% 7% 24% 37% 26%
2020 Ohio statewide summary count 2654 546 541 349 239 294    
total acres average 56.6 1.6 1.5 1.4 1.5 1.6  
150145   % of fields 21% 20% 13% 9% 11% 41% 29%


There were about 2,600 fields and 150,000 acres sampled to make these observations. Enough that we have a good idea of what is happening in each region of the state. The OSU folks will report on local results and answer questions as we have our winter programs.


No area is without some resistant weed. However, pretty much all areas of the state had higher numbers of weed free fields than they had last year. That’s good, but Waterhemp and the pigweed species generally are looking a little scary in all of western Ohio. We know these guys are resistant to numerous herbicides already, and will likely become resistant to more. Mark Loux, OSU Weed Scientist, says mix it up and to rotate herbicide programs across all the packages that work – don’t rely on just one or you will be the one who Mark comes to visit to see just how you blew it.


Who conducts the Fall Soybean Weed Survey by driving 80 miles on the road in each county? In Table 2, is a listing of the counties in the survey and the Extension educator there. This year we had the most counties surveyed – 30 – so the educators are definitely working for you, and want to learn what is happening in your county.


Table 2. County and Extension educator for the 2020 Fall Soybean Weed Survey.

County OSU Extension AgNR educator County OSU Extension AgNR educator
Adams Richard Purdin Henry Garth Ruff
Allen Clint Schroeder Licking Dean Kreager
Ashtabula Andrew Holden Lucas Jordan Beck
Auglaize Jeff Stachler Mercer Denny Riethman
Brown James Morris Miami Amanda Bennett
Champaign Amanda Douridas Montgomery Suzanne Mills-Wasniak
Clinton Tony Nye Pickaway Mike Estadt
Coshocton David Marrison Putnam Beth Scheckelhoff
Darke Sam Custer Ross Chris Bruynis
Fayette Ken Ford Seneca Hallie Williams
Fulton Eric Richer Shelby Matt Schmerge
Geauga Les Ober Trumbull Lee Beers
Greene Trevor Corboy Tuscarawas Chris Zoller
Hancock Ed Lentz Van Wert Curtis Young
Hardin Mark Badertscher Williams Stephanie Karhoff


What can you do to improve soybean weed control? My thoughts.

Actually, I gathered the thoughts for these ideas from good managers – and it sounds an awful lot like the recommendations from Mark Loux our Ohio State University Weed Scientist.

  1. Apply a fall burndown that includes 2,4-D.. plus dicamba, plus glyphosate, or whatever – just don’t spend the money now on a residual. Especially for Marestail control.
  2. Increase the use of metribuzin.
  3. Use of full rate of pre-emergent herbicide at planting in the spring. Even on worked ground.
  4. Consider a switch to LibertyLink or Enlist varieties, and use due diligence on the other herbicide technologies.
  5. And think about a second small-seeded broadleaf residual herbicide at post application timing.

To learn more about managing weeds in Ohio, attend your local county Ohio State University Pesticide and Fertilizer Recertification program. Also don’t forget recertification is a four-hour program, up from three hours we had in the past.


Looking for the best!

The Ohio CCA Board is looking for the best CCA in Ohio, if she or he works with you then please nominate them. The program is sponsoring one state award titled “Ohio Certified Crop Adviser of the Year“. The award is designed to recognize an individual who is highly motivated, delivers exceptional customer service for farmer clients in nutrient management, soil and water management, integrated pest management and crop production, and has contributed substantially to the exchange of ideas and the transfer of agronomic knowledge within the industry in Ohio. Wes Haun of Tiger-Sul was the 2020 winner.

  • Nominee must hold a current Ohio CCA certification and be in good standing.
  • Get the simple-to-complete nomination form: https://bit.ly/OH-CCA-Award21. Send via email to: jwelsheimer@oaba.net or mail to Ohio AgriBusiness Association, 5151 Reed Rd. Suite 126-C, Columbus, Ohio 43220-2598, Attn: Ohio CCA Board.
    • Any questions? Please call Janice Welsheimer at 614-326-7520, ext. 3.

The Ohio Certified Crop Adviser of the Year Award will be presented at the virtual Conservation Tillage Conference on March 9th 2021. The state award includes a plaque, recognition in industry publications, and a cash award from the agronomic industry.


Harold Watters, Field Specialist Agronomic Systems, works out of the OSU Extension office in Bellefontaine and can best be reached at watters.35@osu.edu.

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