Beware of Google/AI Answers (Prostko)

Just got an interesting phone call from an established crop consultant. He asked me about the use rate for Sonalan (ethalfluralin) in field corn.  I replied to him that as far as I know, after working in field corn since 1987, that Sonalan was never or is not now labeled for field corn and I that I would never recommend it, especially PPI or PRE.  Remember, Sonalan is a grass herbicide for use in broadleaf crops.  I then asked him where he got his information.  His reply was that I "Googled" it.  If you Google Sonalan and field corn, here is what shows up:

What would I expect if Sonalan was used in field corn?  Stunting, stubby roots, poor stands, excessive lodging, replanting to a labeled broadleaf crop (i.e. soybean or peanut).  A picture of "yellow" herbicide injury on field corn (Source: S. Berger, IFAS).

This is not the first time I have seen an error with a Google/AI search.  Bottom line, growers/consultants/county agents should not be getting weed control recommendations from Google/AI. 

Enlist® Field Corn Weed Control System (Prostko)

Many Georgia growers are very familiar with the Enlist® (i.e. 2,4-D choline) weed control systems for soybean and cotton.  However, I have not talked very much about the Enlist® weed control system for field corn.  This was primarily due to the fact that there was not a good Enlist® corn hybrid adapted for the SE. I recently learned that Pioneer now has one (P13777PWUE).  Check out this 2024 yield data from Pioneer: 

Consequently, some Georgia growers might now be more interested in trying the Enlist® field corn weed control system (on a limited basis).   A few thoughts about this system:

1) I have not conducted very many weed control trials with the Enlist® system.  My weed science research colleague in Athens (Dr. Nick Basinger) has.  Between his work and mine, it looks like a pretty good weed control system.  I will be conducting additional trials this year.  Check out the following picture from a field trial I conducted in 2018: 

2) Enlist® field corn hybrids are tolerant to 4 different herbicides including 2,4-D choline, Roundup® (glyphosate), Liberty® (glufosinate), and Assure® II (quizalofop).

3) P13777PWUE has the following characteristics:   

4) Because of the previous lack of adapted field corn hybrids, I do not have any specific information listed in the 2025 UGA Pest Control Handbook.  But, I will update for 2026.

5) For more general information about the Enlist® field corn weed control system, check out the following Corteva™ publication:

https://www.corteva.us/content/dam/dpagco/corteva/na/us/en/files/trait-stewardship/product-use-guides/DOC-2025-US-PUG-Corn.pdf

6) Enlist® One Label:

https://s3-us-west-1.amazonaws.com/agrian-cg-fs1-production/pdfs/Enlist_One_Label1gu.pdf

7) Enlist Duo® Label:

https://s3-us-west-1.amazonaws.com/agrian-cg-fs1-production/pdfs/Enlist_Duo_Label1gu.pdf

8) Assure® II Label (pages 10, 14-15 for Enlist® information)

https://s3-us-west-1.amazonaws.com/agrian-cg-fs1-production/pdfs/Assure_II_Label1j.pdf

9) As always, please feel free to reach out to me if you have any questions.

Weed Control in Conventional Corn (Prostko)

Yesterday while attending the Georgia Peanut Commission Research Update, I had the pleasure of sitting next to Tift Co. Extension Agent, Justin Hand.  He mentioned to to me that several of his growers are interested in weed control programs for conventional field corn.  I suspect that many of you might also be interested in this topic so here are a few thoughts:

1) Conventional field corn hybrids are available from several companies.  Here are a few:

Dekalb: DKC59-80, DKC111-30, DKC63-58, DKC66-02, DKC68-37

https://www.cropscience.bayer.us/corn/dekalb/seed-catalog

Dyna-Gro: D57CC51

https://dynagroseed.com/seed-finder/corn?cropsId=dynagroseed:crops/corn

Pioneer: P1197, P1870, P1608, P17677 all have conventional versions but supply might be limited

https://www.pioneer.com/us/product-catalog/crop-corn.html

Please contact our new Extension Grains Agronomist, Dr. Nick J. Shay (Nicholas.Shay@uga.edu) for more information about field corn hybrids. 

2) Here is a slide from my 2025 county presentation about weed control in conventional field corn. Growers need to double-check labels since some herbicide tank-mixes are prohibited (i.e. Callisto and Dual Magnum or Outlook).  Also, growers need to confirm the tolerance of any field corn hybrid to the WSSA/HRAC Group 2, Group 15, and Group 27 herbicides. If Counter is used in-furrow for soil insects/nematodes, Callisto, Revulin Q, and Steadfast Q cannot be applied POST. 

3) Here are some field pictures of these herbicide programs from my 2023 and 2024 research plots. This research was partially supported by the Georgia Corn Commission.

4) Feel free to contact me at any time via phone/text (229-392-1034), e-mail (eprostko@uga.edu), carrier pigeon, or smoke signal. I am available to you 365/24/7!

National Pesticide Safety Education Month (Prostko)

February 2025 is the 8th Annual National Pesticide Safety Education Month (NPSEM).  The NPSEM web-page has lots of good information about basic pesticide safety principles, storage, drift, wildlife protection, etc.  Check out the following web-page for more information:  

https://pesticidestewardship.org/national-pesticide-safety-education-month/

Does Roundup + Atrazine Applied POST in Field Corn Reduce Yields? (Prostko)

    I recently received a phone call from a south Georgia corn farmer who told me that someone was going around saying that a Roundup + Atrazine tank-mix, applied POST in field corn, will reduce yields.  My response was show me the data.  Here is my data from 3 on-farm field trials conducted in a high yield environment (250+ Bu/A) from 2014-2016.  Bottom line, yields from plots treated with Roundup + Atrazine + AMS applied POST were NOT statistically different from the untreated check in all trials.  

    As long as growers follow the label (i.e. rates and timing), I am not concerned at all.  A quick look at the Roundup PowerMax3 label:

USE INSTRUCTIONS: This product may be applied alone or in a tank-mix over the top of field corn hybrids with Roundup Ready 2 Technology from emergence through the V8 stage (8 leaves with collars), or until corn plant height reaches 30 inches (freestanding), whichever comes first, unless otherwise directed. Use drop nozzles for optimum spray coverage and weed control when corn plant height is 24 to 30 inches. When corn plants are 30 to 48 inches tall (freestanding), apply this product using only ground application equipment fitted 16 with drop nozzles aligned to avoid spraying into the whorls of the corn plants. Maximum single in-crop application rate of this product up to 48-inch field corn is 30 fluid ounces per acre. Total in-crop application of this product from corn plant emergence through 48 inches in height must not exceed 60 fluid ounces per acre.

    If a grower uses higher rates than listed above and/or applies Roundup later than suggested, yield losses can occur.  This is what what happens to corn ears when glyphosate is applied at tassel (i.e. way off-label).  

As a reminder, atrazine is only labeled for POST use in field corn up to 12" tall.

New Herbicide Classification Chart (Prostko)

The Take Action Pesticide-Resistance Management Program has recently updated their herbicide classification chart.  This chart has 2 sections including a color coded mode of action/site of action chart and pre-mix herbicide product chart.  This is a very good reference material to have in your office or truck. 

Take Action is a farmer-focused educational platform designed to help farmers manage herbicide, fungicide, and insect resistance. Take Action started with industry-wide collaborative discussions about the growing threat of herbicide-resistant weeds. Parties included representatives from major ag chemical companies, land-grant university weed scientists, and soybean/corn/cotton/sorghum/wheat commodity groups.  Resource development for Take Action on Weeds is funded through a United Soybean Board grant.

A copy of this herbicide classification chart can be downloaded from the following web location:

https://iwilltakeaction.com/wp-content/uploads/2024/11/2025-Herbicide-Classification-Poster-GROW-2024-Oct-V2.pdf

Additionally, I have 100 hard copies of this chart in my office and these are available to anyone who wants one on a first-come/first-serve basis. Just let me know.

For more information about The Take Action Pesticide-Resistance Management Program refer to the following web-site:

https://iwilltakeaction.com/about-take-action/

New Pesticide Data Program Summary (Prostko)

 I am always on the hunt for positive information about the use and need for pesticides in agriculture.  In November of this year, the USDA/AMS released its Pesticide Data Program's 33rd Annual Summary (2023).  This report provides high-quality data on pesticide residues in food, particularly foods most likely consumed by infants and children.  A few highlights of this report are as follows:

1) 9,832 food samples were collected.

2) Fresh and processed fruit and vegetables tested during 2023 were: almonds, apples, avocados, baby food applesauce, baby food carrots, baby food green beans, baby food peaches, baby food pears, baby food peas, baby food sweet potatoes, blackberries (fresh and frozen), celery, grapes, mushrooms, onions, plums, potatoes, sweet corn (fresh and frozen), tomatillos, tomatoes, and watermelon.

3) More than 99% of the samples tested had residues below the tolerances established by the EPA with 38.8% having no detectable residue.    

4) Residues exceeding the tolerance were only detected in 0.49% of the total samples tested.

5) A residue is any amount of pesticide that remains after an application.  A tolerance is the maximum amount of residue that may remain in or on food marketed in the US.  The US EPA determines the maximum residue levels (MRL’s) or tolerance of pesticides in food products based upon a standard 100-fold margin of safety to protect all people and the environment.  In addition to this base margin of safety, the Food Quality Protection Act (FQPA) of 1996 imposed an additional 10-fold safety factor to protect infants and children, unless sufficient evidence is presented to reduce.    

6) A copy of the complete report can be obtained from the following web-site:

https://www.ams.usda.gov/sites/default/files/media/2023PDPAnnualSummary.pdf