"Cracking" Time Tips for Peanuts (Prostko)

Many peanut growers are likely to begin or already have begun treating their fields with early-postemergence ("cracking") applications of Gramoxone (paraquat).  Here are a few tips for success as well as some pictures from "cracking" treatments that I applied just last week:

1) Cracking applications can be applied from peanut emergence up until 28 days after cracking. Cosmetic injury (stunting and leaf necrosis) should be expected.  Generally, this injury will not result in peanut yield loss as long as the label is followed (i.e. application rate and time).  Here is the Gramoxone label for those that might (should) be interested:

https://s3-us-west-1.amazonaws.com/agrian-cg-fs1-production/pdfs/ Gramoxone_SL _3.0 _Label1de.pdf

2) 15 GPA and coarse droplets (VMD₅₀ ≥ 270 microns) are preferred. Gramoxone is NOT LABELED for aerial applications when applied postemergence in peanuts.

3) The UGA recommended treatment (without walking the field) is as follows:  Gramoxone 3SL @ 8 oz/A + Storm 4SL @ 16 oz/A + 1 Group 15 herbicide (either Anthem Flex 4SE @ 3 oz/A or Dual Magnum 7.62EC @ 16 oz/A or Enversa 3ME @ 48 oz/A or Outlook 6EC @ 10.5 oz/A or Warrant 3ME @ 48 oz/A or Zidua 4.17SC @ 2.5 oz/A). I do not have a Group 15 preference.  Anthem Flex will cause more cosmetic injury due to one of its active ingredients (carfentrazone, trade name: Aim).

4) NIS @ 0.25% v/v (32 oz/100 gals) should be included except when Dual Magnum or Outlook are used. Both of these herbicides are EC formulations (oil-based) and therefore have adjuvant-like properties.

5) Growers can make their own Storm (aka "Georgia" Storm) by tank-mixing Ultra Blazer 2SL @ 16 oz/A + either Basagran 4SL @ 8 oz/A or Basagran 5SL @ 6.4 oz/A.  This is a more appropriate ratio for south Georgia and also will be slightly cheaper.  

6) Gramoxone mixing order (from label):

4.4.3 GRAMOXONE SL 3.0 IN TANK MIXTURES: 1. Fill spray tank 1/2 full with clean water or other approved carriers such as clear liquid fertilizer. 2. Add nonionic surfactant to tank 3. Begin tank agitation and continue throughout mixing and spraying. 4. Add dry formulations (WP, DF, etc.) to tank. 5. Add liquid formulations (SC, EC, L, etc.) to tank. 6. Add Gramoxone SL 3.0 to tank. 7. Add crop oil concentrate or methylated seed oil to tank where/if needed. 8. Fill remainder of spray tank

7) Some field pictures from earlier today.  Treatments were applied 4 days ago:

 

Crying Wolf with Valor? (Prostko)

Not sure what's going over the last few days in the peanut patch but I have received numerous inquires about Valor applications ahead of the anticipated rainfall over the next few days.  Here are some reminders to share with overly concerned growers:

1) I have been working with Valor since 1997.  Since that time, I have NO data that proves that when injury occurs, peanut yields are significantly reduced after a labeled/recommended application (3 oz/A within 48 hours after planting, at least 1.5" planting depth).

2) Valor does NOT effect peanut seed germination and radical development.  Recent UGA thermogradient studies indicated that when there is direct peanut seed exposure to Valor at field application rates, there in NO impact on germination and radicle development (Source: Peanut Science (2020) 47:89-93).

3) From 2017-2019, I conducted field trials to evaluate the potential effects of high moisture conditions on peanut response to Valor.  During those trials, peanuts were exposed to 8.0-11.3" of rainfall/irrigation in the first 30 DAP.  Yields were NOT reduced in any year (Source: Peanut Science (2021) 48:113-117). Here is some data for the "Doubting Thomas": 

Figure 1. Peanut yield response to Valor under high moisture conditions in 2018 (UGA Ponder Farm, Ty Ty).  Peanuts were planted 2" deep and Valor was applied 48 hours after planting.  3 oz/A is the labeled and recommended use rate.  

4) Peanuts are most likely to be injured by Valor when higher rates are applied, applications are delayed past 48 hours after planting, peanuts are planted too shallow, and heavy rainfall occurs as the peanuts begin to emerge (i.e. cracking).  Irrigation immediately after application will not prevent Valor injury when heavy rainfall events occur at cracking.

5) Here is an injury picture from some work I did way back in 2009.  Pretty bad but NO yield loss!

Figure 2.  Valor injury 17 DAP (Attapulgus, 2009).  5.44" total rainfall from 

planting until picture was taken. Valor was applied the same day as planting, 

1.75"  planting depth.  

Drought/Dryland Peanuts/Herbicides (Prostko)

No doubt the current drought conditions are on everyone's mind.  Thus, I have been getting tons of inquiries on how to manage herbicides in this situation, especially dryland fields.  I don't have all the answers but here are a few thoughts:

1) Residual herbicides must have moisture to be "activated".  Activation simply means the movement of the herbicide into the upper 1"-2" of soil. This is the depth where most annual weeds emerge from.  Moisture is also needed to keep the herbicide in the soil solution so that it can be absorbed into germinating weed roots and shoots.  

2) In dry conditions, mechanical incorporation will improve the chances for success of some residual herbicides but is not a 100% guarantee under extreme drought conditions.  In a drought, herbicides such as Prowl or Sonalan can be more tightly adsorbed onto soil colloids which makes them less available for plant uptake. If a grower is mechanically incorporating a herbicide and he cannot see the implement behind him because of the dust cloud, its very doubtful that incorporation will matter.

3) Since most residual herbicides only last on the ground for about 7-10 days (~14-17 days for Valor) before they must be moisture activated, it might be a good idea in dryland fields to go "naked" (no PRE) at planting. Wishing/hoping that more reliable rainfall is in the future?  It costs roughly $20-23/A for the UGA standard PRE program of either Prowl or Sonalan (32 oz/A) + Strongarm (0.225 oz/A) + Valor (3 oz/A).  So if it does not rain and these fail to perform, that's good money lost! 

4) A strong "naked" weed control program would include an "AT-CRACKING/EPOST" application of Gramoxone + Storm (brand name or home-made) + a Group 15 herbicide (Anthem Flex, Dual Magnum, Enversa, Outlook, Warrant, or Zidua: FYI, I have no preference here) followed by a timely "POST" application of Cadre + Cobra + 2,4-DB + Group 15.  But, a grower must be ready to pull the trigger in these fields that have no PRE. There can be no delay!!

Figure 1.  "Naked" (no PRE) program for dryland peanuts.  Group 15 herbicides that can be used here include Anthem Flex, Dual Magnum, Enversa, Outlook, Warrant, and Zidua.

5) I do believe that since Valor does last a little longer without moisture activation and is super cheap (~$1/oz), that it might be worth the risk (cheap insurance)?  

Preplant Burndowns for Peanut (Prostko)

I have been getting a few calls about preplant burndown options for strip-till peanut fields.  They say a picture is worth a 1000 words so see below for a few options.  As a reminder, the plant-back restriction for peanut after 2,4-D is 7 days and 0 days (1 oz/A) or 7 days (2 oz/A) for Reviton.  Also, remember that Reviton has no soil residual activity.

Figure 1.  Preplant burndown with Roundup PowerMax3 + 2,4-D amine + Valor EZ, March 27, 2026 (7 DAT), UGA Ponder Farm.

Figure 2. Preplant burndown with Roundup PowerMax3 + Reviton, March 27, 2026 (7 DAT), UGA Ponder Farm.

Droplet Sizes for Contact POST Herbicides (Prostko)

When visiting with your growers, please remind them to use a nozzle/pressure combination that produces COARSE droplets (VMD₅₀ = ≥ 270 microns) when applying contact herbicides such as Basagran (bentazon), Cobra (lactofen), Gramoxone (paraquat), Liberty (glufosinate), and Reflex (fomesafen).  COARSE droplets provide a reasonable balance of drift protection and coverage.  Droplets larger than coarse provide better drift protection but less coverage. Coverage is extremely important for contact herbicides especially when application conditions are not favorable (large weeds, cold temperatures, drought). Various nozzle types and pressures can be used to obtain COARSE droplet sizes (green color on TeeJet chart listed below).

Not playing favorites here with this TeeJet chart but a recent UGA Extension survey indicated that 68% of Georgia farmers use TeeJet nozzles. Other nozzle purveyors include the following:

Greenleaf Technologies: https://greenleaftech.com/

Pentair Hypro: https://www.pentair.com/en-us/flow/hypro/hypro-products/hypro-spraying-products/hypro-spray-nozzles.html

John Deere: https://cdn.prod.website-files.com/66e9e33a09ceaffe3ed4b8dd/66fef97547cff80b92845bf6_JD-Sprayer-Parts-Catalog-2019.pdf

Paraquat Trainings (Prostko)

Since Syngenta recently announced that they will no longer be manufacturing the active ingredient paraquat (https://www.syngenta.com/media/syngenta-cease-paraquat-production-uk-2026), I have received numerous inquires about the future of the US EPA required paraquat safety trainings (https://www.epa.gov/pesticide-worker-safety/paraquat-dichloride-training-certified-applicators#q4).  The following is information that I received from Syngenta on March 13 regarding the issue of paraquat safety training:  

"Syngenta will continue to provide paraquat training via its online training portal while channel inventories of Gramoxone® Herbicide still exist. Our commitment to stewardship, safe use, and regulatory compliance remains unchanged, and we recognize how essential this training is for certified applicators across the country.

 

As we look ahead, Syngenta is actively evaluating options to transition the paraquat training program to an alternative host to ensure continuity beyond our direct involvement. We will share updates as soon as a viable path is confirmed.

 

Thank you for your continued dedication to safe and responsible pesticide application. If you need assistance accessing the training, please reach out to your Syngenta representative or visit the paraquat training portal.  Gramoxone Herbicide is a Restricted Use Pesticide.  Always read and follow label instructions."

Dicamba Preplant in Field Corn (Prostko)

It has come to my attention that the recommendations for preplant/burndown applications of dicamba for field corn in the UGA Pest Control Handbook are NOT sufficiently described.  After closer review of the product labels, there needs to be some adjustment.  Please review the following with any grower who desires to use dicamba for preplant/burndown weed control prior to planting field corn.

1) The newer formulations of dicamba (Stryax®, Engenia®) are NOT labeled for this particular use.

2) Older formulations of dicamba (Clarity®, Rifle®, Sterling Blue®) are labeled for this use depending upon tillage system and soil type as follows:

a) PREPLANT AND PREEMERGENCE APPLICATION IN NO TILLAGE CORN: Rates: Apply 16 fluid ounces of Clarity®, or Rifle®, or Sterling Blue® per acre on medium-or fine-textured soils containing 2.5% or greater organic matter. Use 8 fluid ounces per acre on coarse soils (sand, loamy sand, and sandy loam) or medium-and fine-textured soils with less than 2.5% organic matter.  

b) PREEMERGENCE APPLICATION IN CONVENTIONAL OR REDUCED TILLAGE CORN: Rates: Apply 16 fluid ounces of Clarity®, or Rifle® or Sterling Blue® per treated acre to medium- or fine-textured soils that contain 2.5% organic matter or more. DO NOT apply to coarse-textured soils (sand, loamy sand, or sandy loam) or any soil with less than 2.5% organic matter until after corn emergence.  

c) Failure to follow these recommendations could result in excessive crop injury.  If a grower applies dicamba as a burndown in a field intended to be planted to dicamba-tolerant cotton or soybean and changes their mind and wants to plant field corn, please contact me ASAP. 

3) Everyone always asks me what my preferred burndown is for field corn.  Lots of good choices.  But, I prefer Roundup or Gramoxone + atrazine because these combos will control most of our common winter weeds and field corn can be planted immediately without concern for crop injury.  See below.