Herbicide Adjuvants (Prostko)

At the recent UGA Weed Science Update (12/06/23), Cale Cloud from Grady County asked me if I could talk about herbicide adjuvants.  Since I had my talks already prepared, I did not have the time to go into this interesting and very important topic.  Here are few things for you to consider: 

1) There are numerous adjuvants in the market.  Thus, almost impossible for UGA weed scientists to adequately test all of them.  I could have spent my whole career just testing adjuvants.  

2) Generally, adjuvants can be put into 3 categories including non-ionic surfactants (NIS), oils [crop oil concentrates (COC) or methylated seed oils (MSO)], and fertilizers [usually dry or liquid ammonium sulfate (AMS) or liquid urea-ammonium-nitrate (UAN)].

3) All POST herbicide labels will have a section on recommended adjuvants. 

4) Generally (not always), COC/MSO adjuvants will cause more crop injury and provide slightly better weed control than NIS adjuvants.

5)  Many COC's are actually made from petroleum oils while MSO's are made from vegetable oils (soybean or sunflower).  Both types contain 80-85% oil + 15-20% surfactant. High surfactant oil concentrates (HSOC) contain at least 50% oil + 25-50% surfactant.

6) In my own herbicide testing program, I routinely use Induce (NIS) or Agri-Dex (COC) from Helena unless somebody asks/provides something special.  For over 25 years, both of these have worked just fine for me.  

Induce: https://s3-us-west-1.amazonaws.com/agrian-cg-fs1-production/pdfs/Induce_Label1g.pdf

Agri-Dex: https://s3-us-west-1.amazonaws.com/agrian-cg-fs1-production/pdfs/Agri-Dex_Label1i.pdf

7) Historically, North Dakota State University (NDSU) has been one of the leading land-grants that regularly tests herbicide adjuvants. I included some very good information about adjuvants from the 2023 NDSU Weed Control Guide (W253-23) in the e-mail that I sent to you regarding this specific blog. This info would make a great edition to your "truck" reference materials.

2023 NDSU Weed Control Guide (https://www.ndsu.edu/agriculture/sites/default/files/2022-12/223214_Weed_Color.pdf)

8) Another good resource for herbicide adjuvants is the Compendium of Herbicide Adjuvants.  This publication used to be updated yearly but is no longer.  The latest edition (2016) can be found at the following web-address:  https://mssoy.org/uploads/files/herb-adjuvants-purdue-siu.pdf 

9) If someone is using an adjuvant in your county that you would like to see researched more thoroughly, I can try to fit it into my testing program.  This may or may not happen given my time and space constraints.   

Post-Harvest Weed Control Questions (Prostko)

Still getting a few calls about post-harvest weed control.  Here are a few questions and answers for you regarding post-harvest weed management:

1) What's the best option to control volunteer corn (up to 12" tall)?

Select Max 0.97EC @ 6 oz/A or Select 2EC (clethodim) @ 4 oz/A (or generic equivalents) + COC @ 1% v/v.  I have never had much success controlling volunteer corn with either Liberty (glufosinate) or Gramoxone (paraquat).  Don't forget that many of the corn hybrids grown in Georgia today are RR+LL.  The plant-back restriction for wheat after clethodim is 30 days.  A hard freeze also works well with no plant-back restrictions.

2) Can you control Benghal dayflower/tropical spiderwort with 1 herbicide application?

NO! 2 applications (14 days apart) of either Gramoxone, Aim (carfentrazone), or 2,4-D will be required. Dicamba is NOT recommended for the control of this weed.

3) What is the plant back restriction for wheat after an application of dicamba?

All depends upon the application rate (0.25 lb ae/A = 15 days; 0.50 lb ae/A = 30 days).

4) What is your favorite post-harvest treatment?

I have had good success controlling many post-harvest weeds in my field corn plots, including volunteer corn, with the combination of Gramoxone + Tricor (metribuzin).  But, small grains are not a viable rotational crop option after this one.  Gramoxone + Tricor is much more effective on volunteer corn than Gramoxone alone.  Check out the link and picture below: 

https://s3-us-west-1.amazonaws.com/agrian-cg-fs1-production/pdfs/TriCor_4F_2EE1.pdf

5) Will late-season applications of glyphosate have an influence on weed seed viability/germination next year? 

Generally, glyphosate will only affect weed seed viability/germination if applied around flowering or initial seed set.  Later applications will have little effect on weed seed viability/germination for next season.  

6) Any additional info in 2022 UGA Pest Control Handbook about this topic?

Yes, more specific information can be found on pages 74 (tropical spiderwort) and 86 (Palmer amaranth). 

Peanut Weed Control: Success or Failure?

Check out this picture I took yesterday from one of my weed control studies at the UGA Ponder Farm.  I think you would agree that it looks pretty good at 83 DAP.

Figure 1.  Peanut weed control plots at UGA Ponder Farm (Ty Ty, GA) on July 24, 2023. 83 days after peanut planting (DAP).  No rainfall or irrigation until 8 DAP and 17.92" of total rainfall from May 1 - July 24 (6.86" above long-term average). PRE – Applied 1 DAP; POST – Applied on May 25, 2023 - 22 DAP (Cadre + 2,4-DB + Cobra + Dual Magnum).  Weed-free at planting/twin rows. 

How did I make this happen?

1) I started clean and planted in twin rows.

2) Since I did not get to apply any irrigation until 8 DAP due to an irrigation pump problem, I pulled the trigger early on my POST treatment (22 DAP) and also added Cobra to that treatment. 

3) Spraying weeds when they are smaller in size, works almost 100% of time!  In my opinion, timeliness trumps (or desantiss?) GPA, nozzle type, tractor speed, and boom height.  The effects of these other factors on spray coverage are more critical when herbicides are applied to bigger weeds.  

4) Take a quick look at the Cadre (imazapic) label (https://s3-us-west-1.amazonaws.com/agrian-cg-fs1-production/pdfs/CadreR_Herbicide_Labelp.pdf). With the exception of cocklebur and rhizome johnsongrass, maximum labeled heights for all weeds listed are 4" or less.  A recent growth chamber study conducted on sicklepod control with Cadre indicated 16% less control of sicklepod when Cadre was applied at 6" vs 3" (remember that herbicides always work better in the greenhouse or growth chamber).

5) POST treatments in all my peanut tests are applied in 15 GPA, 3.5 MPH, 20" boom height, and with AIXR11002 nozzles (coarse droplets, 402 VMD50). 

6) It has been well documented that lower GPA's (10 GPA), faster operating speeds (>10 MPH), higher boom heights (>24"), and extremely coarse/ultra coarse spray droplets (i.e. dicamba tips) provide less spray coverage.   

What does this mean for the grower, especially when behind, treating larger weeds, and needing to get better spray coverage?

a) Regardless of any application tweaks, weed control expectations should be lower.  I have never been able to consistently control large weeds in my 37 year weed science career.  Every once in awhile, there are a few exceptions (i.e. bristly starbur/goathead/Texas sandspur and Strongarm).

b) Apply herbicides in 15 GPA.

c) Avoid using nozzle/pressure combos that produce extremely coarse or ultra coarse droplets (VMD50 > 502).

d) Reduce tractor speeds and boom heights as much as possible/practical.

e) Use full labeled rates.

Tank-Mixes, Perennial Weeds, and Pink Purslane (Prostko)

 A few things for you to chew on:

1)  The following are some pictures of a few peanut tank-mixes that I observed over the last few weeks that were not included in previous slides I sent you.  Nothing too scary here.

2)  Last week, I received numerous inquiries about controlling broadleaf perennial weeds in peanut (dogfennel, horsenettle, maypop passionflower, heliotrope, etc.).  None of the herbicides we have in our peanut arsenal work well on these types of weeds.  Growers who have perennial weeds in their peanut fields might consider the following:

a) If perennial weeds are in small spots and growers are willing to sacrifice the peanuts in those spots, they can be spot treated with a high rate of glyphosate (i.e. Roundup PowerMax3 5.88SL @ 44 oz/A or equivalent).  

b) In the fall after harvest, allow perennial weeds to regrow then treat fields with a high rate of glyphosate (same rate as above).  This fall application of glyphosate must be be applied at least 2 weeks before first frost.  Then in the spring of next year, plant RR-field corn or Xtend soybeans/cotton and plan on using a POST combination of glyphosate + dicamba in those crops.

c) It will take multiple years of fall + spring applications of glyphosate to get perennial weeds under control.  It took more than 1 year for these weeds to become a problem and will take more than 1 year to get them under control.

d) Avoid planting peanuts in fields with known populations of perennial weeds.

3) Pink purslane has been a bur under my saddle for many years.  Consequently, my PhD graduate student (Nick Shay) is conducting POST control studies as part of his dissertation.  Nick already completed 2 trials in the greenhouse last fall and 1 field trial this summer.  The following are the recent results of the field trial that he conducted.  Surprisingly, only Aatrex (atrazine) and Cobra (lactofen) were effective in this POST trial.  This field trial will be repeated again later this summer.

Wet Weather Concerns - Part II (Prostko)

Much of Georgia continues to get hammered with frequent rainfall events.  When will it end? Here are some answers to questions you might be getting: 

1) How much has it rained?

Updated rainfall totals from June 12-June 21, 2023

2) What's my best peanut weed control recipe for a disaster field?

a) Apply Select 2EC (clethodim) @ 8-16 oz/A + COC @ 1% v/v then

b) 3 days after the Select application, apply the following combination:  Cadre @ 4 oz/A + Cobra @ 12.5 oz/A + 2,4-DB @ 16 oz/A + any Group 15 herbicide (either Anthem Flex @ 3 oz/A or Dual Magnum @ 16 oz/A or Outlook @ 12.8 oz/A or Warrant @ 48 oz/A or Zidua SC @ 2.5 oz/A).  Include NIS @ 0.25% v/v when using Anthem Flex, Warrant, or Zidua.

c) Costly for sure but desperate times require desperate measures! 

3) Can I also add Strongarm to that mix?

Yes, I did that in 2022 to clean up a peanut field and observed no major problems. Check out the following pics:

4) Is there a shortage of Cobra (lactofen)?

I have heard from several growers that Cobra was not available.  I contacted my inside sources at Valent and this situation should be remedied.   A e-mail quote from my Valent contact yesterday: "Cobra being shipped this week so no excuses moving forward!"

5) Can peanut herbicides be applied aerially by plane or drone?

The short answers is yes (but not Cadre. It does not have an aerial application label) but I have some concerns.  I have been conducting weed control research since 1987.  During this 36 year time frame, I have never applied herbicides in water volumes less than 10 GPA. Coverage, crop injury, and efficacy are my concerns.  There is a ton of work being conducted with drones but I have not seen a sufficient amount of replicated university data to confirm true weed control efficacy.  But in this current rainy situation, perhaps something is better than nothing??????

6) What are the minimum labeled GPA requirements for aerial applications of peanut herbicides?

Butyrac 200 (2,4-DB) = 5 GPA; Classic = 3 GPA; Cobra = 7 GPA; Gramoxone = 5 GPA; Select = 3 GPA; Storm = 5 GPA; Ultra Blazer = 5 GPA 

7) Is Classic still available for late-season Florida beggarweed control in peanuts?

Yes! Check out page 224 in 2023 UGA Pest Control Handbook for updated information about peanut cultivar tolerance to Classic.

https://secure.caes.uga.edu/extension/publications/files/pdf/SB%2028-24_1.PDF

8) Is Gramoxone (paraquat) still labeled for use in peanuts in a non-selective applicator such as a rope-wick or weed wiper? 

Yes!  Check out page 224 in 2023 UGA Pest Control Handbook. Gramoxone applied in this fashion is very effective on Palmer amaranth, Florida beggarweed, and sicklepod.

https://secure.caes.uga.edu/extension/publications/files/pdf/SB%2028-24_1.PDF

For more info:

TopCrop Super Sponge: https://www.smucker.net/weed-wiper-products

GrassWorks Weed Wiper:  https://grassworksmanufacturing.com/

LMC-Cross Wick-Bar: https://www.lmcag.com/

Dayflower Control in Peanut (Prostko)

Here are some quick pics from data collected earlier today about spreading (?) dayflower control in peanuts from our strip-plots in Berrien County (Thanks Gentle Ben and Nick Shay!).  Generally, these are the same herbicide treatments that I typically recommend for tropical spiderwort/Benghal dayflower control as well.  Note that Cadre + Dual Magnum was no bueno!  FYI, Broadloom is a generic formulation of Basagran (bentazon) from UPL (https://s3-us-west-1.amazonaws.com/agrian-cg-fs1-production/pdfs/Broadloom_Label1i.pdf).

Wet Weather Concerns (Prostko)

Over the past few days, many locations in south Georgia have received significant rainfall (Figure 1). 

Figure 1.  Georgia Rainfall (June12-June15, 2023)

A few things to think about:

1) Keep an eye on rain-free periods for postemergence (POST) herbicides.  For my crops, these are listed in the UGA Pest Control Handbook (Remarks and Precautions).  If I am missing one, please let me know.

2) Cool, cloudy, wet weather has a significant influence on the cuticles of plant leaves (i.e. makes them thinner).  Thus, pesticides applied during this type of weather can cause more crop injury symptoms.

3) Residual weed control will likely be compromised (shorter than normal).  Applications of additional residual herbicides should be strongly considered  (Anthem Flex, Dual Magnum, Outlook, Warrant, Zidua).

4) It is also very likely that some growers will not be able to get back into their fields on a timely basis to make POST herbicide applications.  There are no POST herbicides, in any of my crops, that can consistently control a pigweed that is bigger than about 3-4" tall.  Thus, applying herbicides to very large weeds (revenge spraying) is a waste of time and money!  Hand-weeding, mechanical cultivation, non-selective applicators, and mowing are the only effective options for large weeds.

5) Since applications of POST herbicides will be delayed, experience tells me that many growers will want to apply broadleaf and grass herbicides together.  Tank-mixing grass herbicides with broadleaf herbicides (Cadre + Select or 2,4-DB + Select), is labeled/legal but will often result in reduced grass control (~10-20%).  Growers can increase the rate of the grass herbicide (within label) but I prefer a split application (grass herbicide first then broadleaf herbicide ~3-5 days later).

Soil-Applied Dicamba and Peanuts - Uh-Oh! (Prostko)

In the past week, I have been involved with 3 field situations where dicamba was inadvertently applied to peanut prior to planting.  The results were not good.  Dicamba is NOT labeled for preplant use in peanut.  With that said, here is all I know about how peanuts respond to soil-applied dicamba.

1) This is what soil-applied dicamba injury on peanut looks like.  I had to pinch hit that day for Bill "Bob Never Gave Me a Cool Nickname" Starr.  I cannot remember for sure but I I think Bill was hunting Sasquatch in Montana or Wyoming????

2) Field studies that I and several others conducted with preplant applications of dicamba way back in the early 2000's indicated the following:

a) Dicamba at 0.25 lb ae/A (i.e. Clarity @ 8 oz/A or Engenia @ 6.4 oz/A or Xtendimax @ 11 oz/A) applied 7, or 15, or 30 days before planting (DBP) had no effect on yield in 7/7 trials.

b) Dicamba at 0.25 lb ae/A applied 0 DBP (i.e. PRE) caused significant peanut losses in 2/7 field trials.  Peanut yield losses in those 2 trials ranged between 36%-76%.

c) Source:  Prostko, E.P., T.L. Grey, W.C. Johnson III, D.L. Jordan, W.J. Grichar, B.A. Besler, K.D. Brewer, and E.F. Eastin.  2003.  Influence of preplant applications of 2,4-D, dicamba, tribenuron, and tribenuron plus thifensulfuron on peanut.  Peanut Science 30:18-22.

3) From Blanchett, B.H., T.L. Grey, E.P. Prostko, and T.W Webster.  2015.  The effect of dicamba on peanut when applied during vegetative growth stages.  Peanut Science 42:109-120. 

4) The most important factors that influence how peanuts will respond to soil-applied dicamba are application rate, soil type, the time interval between application and planting, and irrigation/rainfall. Based upon my experiences with dicamba on peanuts and soybeans, peanuts could be safely planted 14 days + 1" rainfall/irrigation (0.25 lb ae/A) or 28 days +1" irrigation/rainfall (0.5 lb ae/A) after a preplant application of dicamba.  But, I need to stress again the fact that dicamba is NOT labeled for preplant use in peanut!

Peanut POST's (Prostko)

Here are a couple of quick pics/comments about POST weed control in peanuts based upon research plots that were rated earlier today (June 6).  FYI, I did not get any activating moisture for the PRE herbicides for 8-9 days after planting (DAP) due to irrigation system problems.  PRE treatments that included Valor still performed very well in this scenario.   

Picture #1:

Comments about this picture:

1) No "cracking" herbicides were applied.  I prefer to get Cadre out around 30 DAP.  Not sand-bagging "cracking" treatments.  Gramoxone (paraquat) should be used when needed.  

2) My original intention in this test was to just apply Cadre + 2,4-DB + Dual Magnum POST but the lack of a PRE activating moisture event forced me to add some Cobra, especially when PRE's did not include Valor.

3) If a grower has pigweed and is not sure if it is ALS-resistant or not (most likely will be), it would be a good idea to add either Cobra or Ultra Blazer to the Cadre + DB + Dual Magnum tank-mixture.  Other than price (Cobra is more expensive by about ~$5-10/A), no difference between Cobra or Ultra Blazer when pigweeds are small (<3").  But, Cobra would be preferred if pigweeds are bigger.

4) Growers can also use Anthem Flex, Outlook, Warrant, or Zidua instead of Dual Magnum.  Anthem Flex will cause more leaf burn because it contains a small amount of Aim (carfentrazone). Here is what that looks like 12 DAT.

Picture #3

Comments about this picture:

1) Despite the lack of a timely rainfall/irrigation event, Valor performed very well.

2) No "cracking" herbicides were applied.  I prefer to get Cadre out around 30 DAP.  Not sand-bagging "cracking" treatments.  Gramoxone (paraquat) should be used when needed.  

3) Really no need for an NIS with Dual Magnum or Outlook (EC formulations). But, need NIS when using Anthem Flex or Warrant.

4) Here is what Cadre + Anthem Flex + 2,4-DB + Induce looks like at 6 DAT.

Picture #4

Comments about this picture:

1) Gentle Ben and I (+ Nick Shay, PhD graduate student) put out a quick and dirty test for the control of what we think (?) is spreading dayflower (Commelina diffusa).  We will confirm the exact species (with RC from VSU) when we can collect some plants with flowers.

2) These "cracking" treatments looked great at 3 DAT.

3) Did you know that in Georgia there are 6 species of Commelina and 2 species of Murdannia that look very similar?

Commelina benghalensis - Benghal dayflower (formerly tropical spiderwort)

Commelina caroliniana - Carolina dayflower

Commelina communis - Asiatic dayflower

Commelina diffusa - spreading dayflower

Commelina erecta - erect dayflower

Commelina virginica - Virginia dayflower

Murdannia keisak - marsh dayflower

Murdannia nudiflora - doveweed

Peanut "Cracking" Time Reminders Again (Prostko)

It's that time of year again! Another friendly reminder about peanut "cracking" applications on peanut (a semi-repeat of previous blogs but with 2023 pics).  

1) Gramoxone 2SL @ 12 oz/A or Gramoxone 3SL @ 8 oz/A + Storm 4SL @ 16 oz/A + growers' choice of a Group 15 herbicide (i.e. Anthem Flex, Dual Magnum, Outlook, Warrant, Zidua) + NIS @ 0.25% v/v.

2) No need for NIS when either Dual Magnum or Outlook are used.

3) If growers want to make their own Storm, I would suggest Ultra Blazer 2SL @ 16 oz/A + Basagran/Broadloom 4LC @ 8 oz/A. In case you are wondering, Storm 4SL @ 16 oz/A is equivalent to 11 oz/A each of Ultra Blazer and Basagran/Broadloom.  So my mix is slightly different (hotter).

4) POST applications no later than 28 days after peanut cracking.

5) Check out 2023 field plots below.

Soil-Applied Glyphosate and Peanuts (Prostko)

I received a few questions recently about the use of glyphosate prior to planting or shortly after planting peanuts.  Many of you have remembered (surprisingly!) what Dr. Culpepper has said about the potential residual effects of higher rates of glyphosate on crops such as transplanted squash, broccoli, and collards. Despite what most of us learned in school many years ago, glyphosate does have soil residual properties but it all depends upon the crop and the application rate.  Fortunately, peanut is not a crop that is overly sensitive to glyphosate residues.  In 2020, I conducted a field study to prove this point.  In this study, I applied Roundup PowerMax II 5.5SL at rates ranging from 32 oz/A to 160 oz/A.  Applications were made preplant (6 DBP) or preemergence (1 DAP).  Results indicated that glyphosate had no effect on peanut density, height, width, or yield.  I do not think that a grower should ever use a 160 oz/A rate (5X) but it does prove a point.

  

Valor/Peanut Injury (Again) - Prostko

Last night (May 12), many areas of the state received some rainfall.  In some locations, it was more than 1" (Camilla = 1.47"; Ft. Valley = 2.04"; Midville = 2.67", TyTy = 3.14").  Thus, I am pretty sure that my phone will be ringing off the hook this week about Valor injury in peanuts.  I have discussed this problem many times before in this blog (June 3, 2013; May 4, 2017; May 21, 2020) so check those other posts out.  A few things to remember: 1) This is not a new problem.  Valor injury has occurred somewhere in GA since it was first registered way back in 2001; and 2) History and lots of data suggest that most peanut fields suffering from Valor damage will recover without yield losses.  Here are some pics and data to help you advise your growers not to panic.  Note in the graphs that these plots received more than 8" of rainfall/irrigation within the first 30 DAP and no yield losses were observed even at the 6 oz/A rate.  But, I NEVER want any peanut grower to apply a 2X rate Valor on purpose though!

  

Herbicide Name Recognition (Prostko)

Recently heard of a major whoopsie due to some communication errors.  There are least 3 herbicides floating around Georgia with similar trade names but have very different uses.  Please encourage your growers and dealers to pay close attention to what is being sprayed.

  

Field Corn Weed Control Pictures - 2023 (Prostko)

1) Thought you might be interested in seeing the following pictures from my field corn weed control plots taken over the last week.  For more specific information about these herbicides, check out the 2023 UGA Pest Control Handbook (pages 64-88).  FYI, this is what I am doing when you try to call me between 6 am-9 am.

2) Question #1: Why do I have Prowl H20 3.8SC (pendimethalin) mixed with everything in these treatments?

Texas panicum/buffalograss/bullgrass is one of the most common annual grass weeds in Georgia field corn.  Put very simply, Prowl provides the best residual control of Texas panicum.  If growers are concerned about potential crop injury from Prowl, other residual annual grass control options include Anthem Maxx (pyroxasulfone + fluthiacet), Dual Magnum (s-metolachlor), Outlook (dimethenamid-P), Warrant (acetochlor), and Zidua (pyroxasulfone).  Of these, Anthem Maxx and Zidua are slightly better on Texas panicum (but neither are as good as Prowl).  FYI, Prowl should NEVER be applied PPI or PRE in Georgia field corn, only POST (labeled up to 30" tall/V8).

3) Question #2:  I have heard that Prowl will cause root damage and yield loss when applied to field corn?

A long time ago in a galaxy far far away, Prowl was used as an EPOST (spiking) treatment in combination with atrazine.  Back then, this was about the only way to get reasonable control of Texas panicum.  In that scenario, root pruning was more likely to occur especially when corn was planted <1.5" deep and furrow closure was incomplete.  Delaying Prowl applications allows the corn plant to develop a deeper root system (but still a good idea to plant at least 1.5" deep and have complete furrow closure though).  For many years, I have been applying Prowl POST with various herbicides and have never observed any significant yield losses.

Week of April 17 - Questions and Answers (Prostko)

Here are some questions (and my answers) that I received this week from various county agents and other clients.

1) If Zidua 4.17SC (pyroxasulfone) is applied postemergence for the residual control of pigweed, annual grasses, and tropical spiderwort, what are the labeled stages of growth for application in field corn, soybean, and peanut?

field corn = spiking up to V8 (this is later than what is currently listed in the 2023 UGA Pest Control Handbook)

soybean = cracking up to V6 (Personally, I would prefer after the soybeans have fully emerged and are growing well)

peanut = cracking up to beginning pod development (R3)

2) How do non-Liberty (glufosinate) tolerant field corn hybrids respond to off-target movement of Liberty?

ASC and and I both think that drift rates are likely around 1/100X and lower.  I do not have any local data from Georgia but check out the following information from LSU.  These data suggest that Liberty rates ≤ 1/50X will cause less than 5% yield losses.

Here is a picture of Liberty injury on field corn.

3) Where can I get information about soybean variety tolerance to metribuzin?

The following table is listed in the 2023 UGA Pest Control Handbook (page 280):

For additional soybean cultivar/metribuzin tolerance information, check out the following from the University of Arkansas:

https://www.uaex.uada.edu/farm-ranch/crops-commercial-horticulture/soybean/2021-Metribuzin-Tolerance-of-Soybean-Varieties.pdf

When considering using metribuzin on soybean, cultivar tolerance is very important but there are other factors to consider as well including application rate, soil texture, OM, pH, and planting depth.  Growers should read metribuzin labels very carefully prior to use.  Here is a list of soybean herbicides than contain metribuzin.