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

Corteva Enlist® Training (Culpepper/Prostko)

We just wanted to make you aware of the fact that Corteva will be hosting several Enlist® training meetings in AL, GA, and SC.  Topics to be covered include tank-mixing, nozzle selection, sprayer cleanout, weather, and field planning.  Since the dicamba cotton/soybean labels are currently vacated, it is likely that we could see more use of Enlist® One (2,4-D choline) and Enlist® Duo (2,4-D choline + glyphosate) in both cropping systems.  For more information about the Enlist® weed control system, check out the following web-site: Enlist.com

Post-Harvest Tropical Spiderwort/Benghal Dayflower Control (Prostko)

Field corn growers who do not control tropical spiderwort/Benghal dayflower in the fall after harvest are missing a HUGE opportunity to reduce seed-rain back into a field.  Failure to control this plant in the fall is one reason why many Georgia growers continue to have major problems with this weed.  

Check out the following data/pictures from a test that we currently have in a Grady Co. harvested corn field (Thanks Cale!).  You will note that the most effective treatment at this time was a split application of Gramoxone 3SL @ 32 oz/A + Induce @ 0.25% v/v.  I would expect better control from the other treatments if they would have been applied earlier to smaller plants and/or also included a COC or MSO (I was trying to save $$ and determine if a tank-mix with a "loaded" glyphosate would be adequate).   

Since we are not likely to get a hard freeze until ~November 15 in south GA, there is still plenty of time left for tropical spiderwort/Benghal dayflower to produce viable seed.  Viable/ripe seed can be produced within 14 to 22 days after aerial flower opening.  Additional information about the post-harvest control of tropical spiderwort/Benghal dayflower can be found on page 74 of the 2024 UGA Pest Control Handbook.

Newer county extension agents might also want to print out this publication that the UGA Weed Science Team wrote a few years ago.  It's still very relevant.

https://secure.caes.uga.edu/extension/publications/files/pdf/C%20884_2.PDF

Soybean Desiccation/Harvest Aid Reminders (Prostko)

Recently, I have been getting a few inquiries about soybean desiccation and harvest aids.  A few reminders.

1) Official soybean harvest aid rec's from from the 2024 UGA Pest Control Handbook (pages 263-264);

https://secure.caes.uga.edu/extension/publications/files/pdf/SB%2028-28_2.PDF

2) Check out these previous UGA Weed Science Blogs where I addressed this topic:

October 13, 2014:

https://ugaweedscience.blogspot.com/2014/10/avoid-early-harvest-aid-applications-in.html

October 28, 2018: 

https://ugaweedscience.blogspot.com/2018/10/do-harvest-aid-applications-of-paraquat.html

3) Check out these newer publications from LA and MS. In 2024, these two states collectively planted ~3.42 million acres of soybeans and my colleagues in these states have done a significant amount of research on this topic. Thus, they might know what they are talking about.  

    Louisiana State University: 

https://www.lsuagcenter.com/~/media/system/5/f/c/e/5fce06f97b891599afaab6b0d6fc3963/p3885_desiccatingsoybean_rh723pdf.pdf

    Mississippi State University

https://extension.msstate.edu/sites/default/files/publications/publications/P3916_web.pdf

4) Friendly reminder that I am more than happy to spend a day in any county looking at problems and/or teaching/coaching weed science.  Just give me a call (229-392-1034).  Out of town this week at a weed science meeting but after that my schedule is very flexible.

Peanut Weed Control Update - July 22 (Prostko)

 I thought you might be interested in a few pictures from our peanut weed control plots taken earlier today.

A few comments: 

1) UGA's recommended weed control program [a) starting clean, b) planting in twin rows, c) using multiple residuals at planting that get activated by irrigation and/or rainfall, and d) making timely (34 DAP) POST applications] looks very good as usual.  This location has received 14.12" of rainfall since May 1 (3.56" above average) and the residual herbicides have lasted longer than anticipated.  

2) Once again, I see no significant differences in weed control between Prowl or Sonalan-based weed control programs.

3) The only tweeks to this program would be the addition of either Cobra or Ultra Blazer to the Cadre + 2,4-DB + Dual Magnum POST treatment.  Also, could use other Group 15 herbicides depending upon grower preference (Anthem Flex, Outlook, Warrant, Zidua).  Remember, Cobra has performed better on larger pigweeds than Ultra Blazer.

4) Generally, peanut growers have all the tools that they need for weed control (except for perennial broadleaf weeds).  Just have to figure out a better way for them to be more timely?  

Carpetweed in Peanut (Prostko)

I have been getting lots of questions recently about the control of carpetweed (Mollugo verticillata) in peanut.  Check out these pictures from Ben Reeves (Berrien Co.) who sent them to me earlier today. 

A few things to chew on:

1) Carpetweed is summer annual weed native to the U.S.

2) Other common names for this weed include green carpetweed, Indian chickweed, whorled chickweed, and devil's grip. 

3) Carpetweed is listed as a controlled weed on EVERY peanut herbicide label except for Basagran (bentazon), Butyrac (2,4-DB), Classic (chlorimuron), Strongarm (diclosulam), and the POST grass herbicides [Fusilade (fluazifop), Poast (sethoxydim), and Select (clethodim)]. So...?

4) No confirmed cases of herbicide-resistance in carpetweed have been reported worldwide. (https://www.weedscience.org/summary/species.aspx)

5) Carpetweed has been in my research plots for 15+ years.  I have never failed to control it with my recommended peanut weed control programs (http://www.gaweed.com/newest-prostko-2024-control-peanut-corn-soy.pdf).

6) Possible reasons for lack of carpetweed control in 2024 are as follows:

a) Too wet?  Residual herbicides do not last as long; growers cannot get into fields on timely basis; unexpected pop-up showers occur before rain-free period is reached. 

b) Too dry? Residual herbicides do not get activated on a timely basis; big weeds + dry weather are a POST herbicide's Achilles heel.

c) Reduced herbicide rates?  Many growers are not using full labeled rates of herbicides such as Cadre (imazapic) to help prevent carryover in 2025.  We proved many years ago that this strategy does not really work.  Cotton will find Cadre in the soil when a lab analysis will not.  More importantly, when reduced rates are used and less than 100% weed control is obtained, the evolution of herbicide-resistance is greatly increased.  Yes, we can control some weeds with reduced herbicide rates (i.e. bristly starbur/Strongarm) but this tactic does not work for every weed and every herbicide. 

An Interesting Exchange (Prostko)

Thought everyone might benefit from this recent text conversation that I had with one of the best peanut/cotton growers in the state of Georgia.  Here it is. 

Grower Question?

Do you think I can apply this product [Ag-Min (30% Mn + 15% S)] with 2,4-DB?

.  

Prostko Response:

There have been some issues in the past with Mn + DB.  See below.   Also, my colleague at NC State University (Dr. David Jordan) has seen some problems as well. Last few years some weird stuff has happened.  Might be better to co-apply with fungicide.

 

Recent NC State Blog (07/03/24): 

https://peanut.ces.ncsu.edu/2024/07/manganese-and-24-db-peanut-notes-no-135-2024/

Grower Response 1 Day Later:

So I rolled the dice.  I have the ability to circulate my mixing vat to fully dissolve dry matter.  Also, my sprayer has good agitation.  I am running 15 GPA, so probably a more diluted spray solution that most.  I still made polyester.  I am telling you, not to admit that I am an idiot for not heeding your warning, but so that you can tell others that ask.  It's absolutely a no go!

Prostko Response 1 Day Later:

At least you were wearing PPE! 

Strongarm/Cadre/Cobra - Prostko

 A few quick comments based upon texts, e-mails, and phone calls this week:

1) Clethodim + Strongarm + Crop Oil + AMS Tank-Mixes????  Nothing better than good data.  See chart below.  Anywhere from 0% to 17% less grass control when Strongarm was mixed with Select.  You may recall that grass control is often reduced when POST grass herbicides are tank-mixed with certain fungicides and herbicides (i.e. antagonism).  Antagonism can be avoided by applying the POST grass herbicide first then applying the other agri-chemicals ~3 days later.

2) Cadre Programs?  Check out this picture from my peanut plots earlier this morning.  Further proof of the need for Cobra (or Ultra Blazer) + any Group 15 herbicide (Dual Magnum, Outlook, Warrant, Zidua) applied in combination with Cadre + 2,4-DB.  Most or all of the Palmer amaranth populations in Georgia have some level of resistance to the ALS-inhibiting herbicides.  

3) Is there a Cobra shortage?  According to my contacts as Valent, there are about 20,000 gallons of Cobra sitting in a warehouse in Albany, GA.  My contacts at Triangle tell me there is at least 1 pallet (180 gallons) of Cobra at their facility in Leesburg.  Not sure why some dealers are reluctant to procure some Cobra?????

4) My schedule over the next few weeks:

a) July 8-July 11: APRES (Oklahoma City, OK).  Still available via e-mail, phone, text, smoke signal, 24/7.  

b) July 12-21: I will be on vacation.  Please try to reach me via e-mail. I will be looking at my e-mails at least once/day in the early AM.  If you have an emergency (i.e. a WTF moment), shoot me a text and I will try to call you back ASAP.  Herbicide application rates, timings, rain-free periods, PHI, etc. are NOT an emergency.  All of this type of information can be found in 2024 UGA Pest Control Handbook.  However, more than happy to take those types of questions when I am in town.        

Cadre (imazapic) Review - Prostko

Lately, I have been getting a lot of calls about the use of Cadre (imazapic) in peanut.  Since we have many new county extension agents and us old folks have fading memories, I thought it might be a good time for a quick review.  Here are 10 things about Cadre you may or may not have known.   

1) The active ingredient in Cadre was first discovered in 1981 by American Cyanamid Company.  

2) Cadre was first registered for use in peanut in 1996.

3) Cadre was tested under the code number AC-263,222.  Much of the foundation research on AC-263,222 was conducted in Georgia [Drs. John Wilcut (former VT, UGA and NCSU Research Weed Scientist) and John Richburg (Corteva)].

4) Cadre was first formulated as a 70DG but is now sold a 2AS.

5) Although most peanut growers usually apply Cadre around 30-45 days after planting (DAP), it can be applied earlier.  Peanuts have excellent tolerance to Cadre.  Check out this older Georgia yield data. 

6) In some other countries (i.e. Australia), imazapic is applied preemergence (PRE).  Cadre is not labeled for PRE applications in Georgia peanuts because PRE applications are more likely to result in cotton carryover problems (and other sensitive crops) and also can be less effective on Florida beggarweed.

7) Cadre can occasionally cause "yellow flash" injury when used in peanut.

8) ALS-resistant Palmer amaranth was first confirmed in Georgia in 2000 after collecting seed from a peanut field where Cadre treated plants survived the application.

9) ALS-resistance in yellow nutsedge was confirmed in Georgia in 2021.  In this field, peanuts were grown continuously for 4 years where ~18 oz/A of  Cadre was applied during that time period.  Not the normal use pattern or rotation sequence for most of Georgia.     

10) Imazapic is sold under many trade names including Impose, Plateau, and Comrade.

"Georgia" Storm for Peanut/Soybean Tank-Mixes (Prostko)

1) Since the agent training in Tifton on June 6, I have had numerous questions about the "Georgia" Storm that I talked about in peanuts.  The commercial formulation of Storm 4SL from UPL is a pre-mixture (i.e. 1 jug) of acifluorfen (1.33 lbs ai/gal) + bentazon (2.67 lbs ai/gal).  The normal recommended use rate (by me) of commercial Storm is 16 oz/A when combined with Gramoxone (paraquat) in an early-post or "cracking" spray.  Storm @ 16 oz/A is equivalent to rates of ~11 oz/A of Ultra Blazer 2LC (acifluorfen) + ~11 oz/A of Basagran/Broadloom 4LC (bentazon). In my opinion, 11 oz/A of Basagran/Broadloom is sometimes too much in this mix.  At this rate, Basagran/Broadloom will reduce peanut leaf burn but could also reduce efficacy on some weeds in certain scenarios (i.e. larger Florida beggarweed and sicklepod). 

I use the term "Georgia" Storm when growers choose to make their own by tank-mixing Ultra Blazer 2LC @ 16 oz/A and Basagran/Broadloom 4LC @ 8 oz/A (i.e. 2 separate jugs).  These application rates are more ideal for the general weed complex that growers have in most Georgia peanut fields.  Based upon some recent price estimates, "Georgia" Storm is ~$1.75/A cheaper than the commercial Storm.  But, many growers prefer the convenience of only having to deal with 1 jug. Both Storm and "Georgia" Storm have performed very well in my 2024 research plots.  See below.    

    

2) I have had a a bunch of questions about the following tank-mixes in soybean.  When I was conducting my original on-farm tropical spiderwort research in the early 2000's, Liberty-Link soybeans were not yet commercialized (2009) and dicamba-tolerant soybeans were a pipe dream. Please note that Basagran is not labeled for use in combination with Engenia according to the latest tank-mix information (https://www.engeniaherbicide.com/tank-mix.html).  However, Basagran is labeled for use with Xtendimax (https://www.xtendimaxapplicationrequirements.com/#/intro).

Cadre Time in Peanut (Prostko)

Peanut growers should be seriously thinking about beginning their POST herbicide applications as early as 30 DAP.  Some peanut growers will choose to use Cadre (imazapic).  Others may not want to use Cadre due to crop rotation/carryover concerns.  Here are a few things to consider:

1) Growers who will be using Cadre need to consider the fact that much of the Palmer amaranth in Georgia is resistant to the ALS-inhibiting herbicides.  Thus, it's a a a good idea to tank-mix Cobra (lactofen) or Ultra Blazer (acifluorfen) with Cadre to address this particular issue. If Cobra or Ultra Blazer are not included, it will be too late to control those pigweeds once a grower discovers that they are ALS-resistant.  

2) If a grower cannot use Cadre, then Cobra or Ultra Blazer are the best options for pigweed.  When pigweed plants are small (2"-4"), there is not much difference in control between Cobra or Ultra Blazer.  However, Cobra is more effective on larger weeds (>4").  But, Cobra will cost about ~$9/A more than Ultra Blazer.  It is important to remind growers that if Cadre is not used in peanut, it is very likely that yellow/purple nutsedge and sicklepod/coffeeweed will be a problem.  

3) If sicklepod is also present in the field, Butyrac (2,4-DB) should be included in the tank-mix. I recently heard from a grower in Middle Georgia that there was a rumor floating around that I only recommended 12 oz/A of 2,4-DB in peanuts.  To set the record straight, I recommend the use of 12 oz/A of 2,4-DB, if needed, when it is tank-mixed with Gramoxone (paraquat) + Storm (bentazon + acifluorfen) + Group 15 when applied early-postemergence (i.e. cracking spray).  I usually recommend 16-24 oz/A of 2,4-DB when it is applied POST with Cadre or Cobra or Ultra Blazer.  

4) Because pigweed and annual grasses are such a problem in most peanut fields, it's also a good idea to think abut including a Group 15 herbicide that will provide additional residual control of these weeds.  Group 15 herbicides include the following: Dual Magnum (S-metolachlor), Outlook (dimethenamid-P), Warrant (acetochlor), and Zidua (pyroxasulfone).  Not much difference in weed control between the Group 15 herbicides but Zidua has provided slightly better residual control of Texas panicum in my research trials over the years.

5) When Dual Magnum or Outlook are included in POST tank-mixtures, additional adjuvants are not recommended because these are EC (emulsifiable concentrates i.e. oil-based) formulations.  NIS (0.25% v/v) is recommended if any of the other Group 15 herbicides are used since they are not EC formulations. 

6) Check out Figure 1 below.  These pictures were taken from my plots on June 3, 2024.   Since the Palmer amaranth population at this location is ALS-resistant, I am getting much better control with the Cadre + Cobra or Ultra Blazer tank-mixes. 

7) Note that I have included the estimated prices/A for each of these treatments.  These are average prices that I have obtained from several dealers so they will very likely be slightly different for every grower.   

  

Figure 1.  Weed control in peanut with Cadre/Cobra/Ultra Blazer/2,4-DB/Dual Magnum tank-mixtures in peanut, UGA Ponder Research Farm, Ty Ty, GA, June 3, 2024.

Wet Weather and Peanuts - 2024 (Prostko)

1)The current rainfall event that is occurring in many parts of Georgia will likely result in Valor (flumioxazin) injury in some peanut fields.  I do not feel they need to reinvent the wheel, so please check out the following previous 6 blogs where I have addressed the Valor/peanut injury issue: 

June 3, 2013: https://ugaweedscience.blogspot.com/2013/06/valor-injury-on-peanut-prostko.html

May 20, 2014: https://ugaweedscience.blogspot.com/2014/05/peanut-injury-update-prostko.html

May 26, 2017: https://ugaweedscience.blogspot.com/2017/05/valor-injury-or-sky-is-falling-prostko.html

May 21, 2020: https://ugaweedscience.blogspot.com/2020/05/valor-injury-on-peanut-is-likely-prostko.html

May 23, 2021:https://ugaweedscience.blogspot.com/2021/05/irrigating-peanut-fields-treated-with.html

May 13, 2023: https://ugaweedscience.blogspot.com/2023/05/valorpeanut-injury-again-prostko.html

TAKE HOME POINT FOR THE VALOR/PEANUT INJURY ISSUE: VALOR INJURY IS LIKELY BUT YIELD LOSS IN NOT!

2) Peanut growers who have missed the recommended application timing for applying Valor + Strongarm + Prowl or Sonalan (PRE) should not panic.  My suggestion would be to let the peanuts emerge, then treat herbicide "naked" fields with an EPOST application of Gramoxone + Storm or Basagran + Zidua or Anthem Flex + NIS (Page 221 of 2024 UGA Pest Control Handbook).  I usually do not have a preference between the Group 15 herbicides (Anthem Flex, Dual Magnum, Outlook, Warrant, Zidua).  However in fields that were not treated with any Prowl or Sonalan, I do prefer Anthem Flex or Zidua in the first EPOST treatment because these herbicides provide slightly better control of Texas panicum (i.e. bullgrass or buffalograss).  Check out the picture below from my 2023 research plots.  No PRE herbicides were applied (on purpose) but I was still able to obtain very effective weed control.  This situation is not ideal but growers can make it work.    

Liberty + Roundup/Paraquat + Diuron + Fomesafen (Prostko)

A few things to chew on: 

1) I have gotten many questions about tank-mixing Roundup + Liberty for weed control in field corn.  Check out this picture from my 2024 plots (May 6).  No real difference in weed control between 22 oz/A or 27 oz/A or 32 oz/A of Roundup + Liberty (tank-mixed with Atrazine and Prowl).  Field corn looks a little ratty because the farm received 0.9" of rain on May 4 and some hail.

2) Justin Hand (Tift Co. Agent) and I just got back from trying to help a grower figure out a tank-mixing problem he was having with NIS + diuron + fomesafen + paraquat.  Turns out that the problem was related to the diuron formulation.  No problems with the Direx (Adama) formulation (left) but a significant problem with the Diuron (Drexel) formulation (right).  

, 

Halex GT Mixing Problem in Corn/Valor Applied PPI (Prostko)

 A couple of things to bring to your attention based upon my week:

1) A field corn grower in Macon Co. experienced a significant problem when Halex GT (mesotrione + S-metolachlor + glyphosate-K salt) was tank-mixed with a different type of glyphosate formulation (IPA salt) (Figure 1).  This problem did not occur when other K salt formulations (Roundup PowerMax3 or Honcho K6) were used (Figure 2). Remember that all glyphosate formulations are not created equal.  They have different concentrations of active ingredients, are formulated as different salts (K, IPA, DMA), and may/may not be formulated with adjuvants. In my April 8 blog, I provided you with a couple of links where you can get some handy information (charts) about the different glyphosate formulations.

Figure 1.  Halex GT tank-mixing problem in Macon County, 2024.

Figure 2.  Different glyphosate formulations tank-mixed with Halex GT + Atrazine +
Mustang Max + NIS + Defoamer

2) Please remind your growers that UGA does not recommend that Valor be applied pre-plant incorporated (PPI) for weed control in peanut!  Valor is not labeled for that type of application and pigweed control will be significantly reduced (PPI is 25-35% less effective than when applied PRE behind the planter).   

 

Figure 3.  Palmer amaranth control in peanut with Valor applied PPI or PRE.

Wet Weather and PRE Herbicides (Prostko)

In the last 2 days, many locations in south Georgia received lots of rain (Figure 1).  Thus, I have been getting many texts and telephone calls about what might happen to any PRE herbicides that were applied to field corn.  In general, I would say that if runoff/washing was minimal, there is a good chance that the herbicides are still in the field, especially if the PRE treatments were watered in soon after application.  Research in Georgia has shown that runoff of Dual II Magnum and Prowl EC in conventional tillage systems was reduced 1.2-2X when irrigation occurred shortly after application (Potter et al. 2008.  Herbicide incorporation by irrigation and tillage impact on runoff loss.  Journal of Environmental Quality 37:839-847).

In 2022, a very similar weather event occurred in my research plots during the first 7 days after planting (3.84" of irrigation/rainfall).  All my PRE herbicides worked just fine (Figures 2, 3, 4).  Note in Figure 2 that there are some wild radish plants in the plot but no pigweed or grasses.  In general, all of the Group 15 herbicides (Anthem Maxx, Dual Magnum, Outlook, Warrant, Zidua) do not provide adequate residual control of wild radish so this should not be a surprise.  FYI, Anthem Maxx/Zidua are slightly better on wild radish than the other Group 15's.

Bottom line, no way to know for certain how much herbicide will be left in the field.  My best advice would be to keep eyes on/feet in the field and pull the trigger earlier on POST treatments when/if needed.  

Figure .  South Georgia Rainfall, April 10-11, 2024.

Figure 2.  Weed control with Everprex in a rainy year.

Figure 3.  Weed control with Acuron in a rainy year.


Figure 4.  Weed control with Maverick in a rainy year.

Roundup (glyphosate) + Liberty (glufosinate) for Weed Control in Field Corn (Prostko)

Over the weekend, I fielded a few questions about the potential use of a Roundup + Liberty tank-mixture for weed control in field corn.  A few years ago, I was not really a huge fan of this tank-mix because I was worried about possible antagonism (i.e. less weed control) since they are very different herbicides.  Roundup is a systemic (translocated) herbicide while Liberty is a contact herbicide (limited movement within a plant).  I have heard ASC talk positively about this tank-mixture in cotton over the years but he has also observed some reduced grass weed control with this combo.  

In my field corn research thus far, I have not seen this antagonism (yet?) but I am also adding either Aatrex (atrazine) and/or Prowl (pendimethalin) to the mix.  Aatrex 4L @ 2 qt/A brings much to the table. Check out the field pictures below.  You might also observe in these pictures that I did not add any additional adjuvants to these treatments because a) I do not have hard water [excessive Ca, Fe, K, Mg, Na] and b) "loaded"  glyphosate formulations [formulations already have adjuvants included] were used.  If you are not sure about which glyphosate formulations are "loaded" or not, check out the following (no need to reinvent the wheel) :

https://www.ag.ndsu.edu/publications/crops/north-dakota-weed-control-guide (From North Dakota State University, page 93)

https://extension.msstate.edu/sites/default/files/publications/publications/P1532_web.pdf (From Mississippi State University, pages 12-13)

A few other things to think about?  1) Not all field corn hybrids are tolerant to both Roundup and Liberty so that needs to be confirmed before application and 2) Labeled cutoff stages for over-the-top applications for each herbicide are very different (Atrazine = 12"; Liberty = V6; Prowl = 30" or V8; Roundup = 30" or V8). 

Coverage, Coverage, Coverage (Prostko)

In support of Dr. Bob "Hole in My Roof" Kemerait's 6:29 am e-mail earlier today, I would like to add a few comments about spray coverage.  I don't sleep that much this time of year especially when its field corn planting time and it's too rainy/windy to plant/spray.  Three quick reminders about spray coverage that we often talk about (with some data to back them up):

1) Increased tractor speeds result in decreased spray coverage. 

2) Lower water volumes result in decreased spray coverage.

3) Larger spray droplets result in decreased coverage.

In the words of Forrest Gump, "That's all I have to say about that!"

Zalo Herbicide Registration (Prostko)

The registration for AMVAC's Zalo herbicide (glufosinate + quizalofop) was recently granted by the US EPA on February 13, 2024. Considering the current shortage of the over-the-top dicamba products (Engenia, Tavium, and Xtendimax) in Georgia, cotton and soybean growers will very likely be interested in any or all glufosinate formulations. For more information, check out the slides below.  

Adjuvants-Part II (Prostko)

You might recall that I provided you with some general information about spray adjuvants in a December 11, 2023 UGA Weed Science blog post.  I was not aware of (or more likely forgot) that there is an Adjuvant Certification Program spearheaded by the Council of Producers and Distributors of Agrotechnology (CPDA).  Adjuvants that have this certification have met 17 benchmark qualifications of a consistent and quality adjuvant. More information and a complete list of CPDA certified adjuvants can be found at https://cpda.com/adjuvant-certification-history-2/.

Ryegrass Control/Reviton-Peanut Rotation Restriction Change (Prostko)

 A few things you might be interested in:

1) Lately, I have received a few questions about controlling Italian/annual ryegrass in preplant burndown situations.  Assuming resistance is not an issue, glyphosate can be effective but remember that rate and timing are very import (Figure 1).  If you suspect that glyphosate-resistance (GR) is an issue, check out page 85 of the 2024 UGA Pest Control Handbook.  On the bottom of page 85, I have more detailed information about controlling GR-ryegrass.

 https://secure.caes.uga.edu/extension/publications/files/pdf/SB%2028-15_2.PDF  

Figure 1.  Ryegrass Control with Roundup WeatherMax at Different Rates
and Stages of Growth.

2) Via a FIFRA Section 24(c) label, the crop rotation restriction for peanut in Georgia following an application of Reviton (tiafenacil) has been reduced to 0 days (1 oz/A ) and 7 days (2 oz/A).  Refer to the 24(c) label below.  Check out the February 7, 2022 and March 31, 2023 posts on the UGA Weed Science Blog for some earlier comments about Reviton.  

Figure 2.  Section 24(c) Label for Reviton (tiafenacil) in Georgia 

2024 Peanut Herbicide Prices, Field Corn Hybrid Herbicide Tolerance Guides - Prostko

 1) Thought you might be interested in the current prices of peanut herbicides.  These prices were obtained by averaging numbers from at least 4 local retailers.  Also, need to realize that every grower will likely pay a different price than listed below based upon many factors (probably lower).

Anthem Flexx = $621/gal; Basagran = $60/gal; Brake = $187/gal; Butyrac 1.75SL (2,4-DB) = $21/gal; Cadre = $250/gal; Cobra = $181/gal; Dual Magnum = $69/gal; Gramoxone 3SL = $40/gal; Outlook = $134/gal; Prowl H2O = $49/gal; Select Max = $92/gal; Sonalan = $50/gal; Storm = $90/gal; Strongarm = $756/lb; Ultra Blazer = $46/gal; Valor EZ = $461/gal; Warrant = $30/gal; Zidua SC = $710/gal.

Using these numbers then ......

Sonalan 3EC @ 32 oz/A + Valor EZ 4SC @ 3 oz/A + Strongarm 84WG @ 0.225 oz/A (PRE) fb Cadre 2AS @ 4 oz/A + Dual Magnum 7.62EC @ 16 oz/A + Butyrac 1.75SL @ 16 oz/A  (POST) =  $53.01/A

2) Check out the most recent editions of the field corn hybrid herbicide tolerance information from Pioneer and Dekalb.  Always a good idea to double-check BEFORE spraying.

Amides: Dual Magnum, Outlook, Warrant

Benzoic Acid/Phenoxy: 2,4-D, dicamba

Isoxazole: Callisto, Laudis, Impact

Sulfonylurea: Accent, Revulin Q, Sandea, Steadfast Q 

Pioneer:

Dekalb: