Florida Beggarweed in Peanut (Prostko)

I was texted the following picture (slightly blurry) early yesterday morning from a SW-GA crop consultant.  He commented that it was all over the field.

This is Florida beggarweed (kidney-shaped cotyledons).  When I first got to GA in 1999, Florida beggarweed was the #1 peanut weed.  It became less troublesome when Valor (flumioxazin) was registered in 2001 (very effective) and when Palmer amaranth exploded. Florida beggarweed tends to be a later emerging weed and prospers during wetter conditions. 

At this point in the growing season, there are not many good options for controlling Florida beggarweed in peanut. The first option is a POST (60 days after peanut emergence) application of Classic (chlorimuron).  The other option is to use Gramoxone (paraquat) in a non-selective applicator (wiper, sponge, rope-wick).  Both of these options are described on page 224 of the 2025 UGA Pest Control Handbook and/or listed below. Please carefully read the comment sections of these recommendations.  Peanut cultivar tolerance to Classic is a major concern.  If a newer peanut cultivar is not listed in the comment section (i.e. Arnie, TifNV-HG, etc.), that means I DO NOT have any tolerance data and have no clue what will happen.

For the Doubting Thomas (Prostko)

Here is a quick picture from my research plots earlier today.  Further proof that herbicides work well when applied on time.  Generally, I do not have any preference for what Group 15 herbicide is used in this EPOST + POST program (Anthem Flex, Dual Magnum, Enversa, Outlook, Warrant, or Zidua).  But, I would prefer that our growers not tank-mix Anthem Flex with Cadre + Cobra + 2,4-DB (POST) at this time (i.e., I need more data).  Also, please keep in mind that these are average prices and prices may be more or less depending upon the grower.  

If you need more info about herbicide mechanisms of action (Groups), check this out from the Weed Science Society of America:

https://wssa.net/wp-content/uploads/WSSA-Mechanism-of-Action.pdf

More Tank-Mix Stuff (Prostko)

 1) Here is a quick picture of a recent peanut tank-mix from JB in Wilcox Co. that was applied without a hitch. I would welcome more pictures from any County Agent of good and bad tank-mixes.  If you send me a tank-mix picture, try to get planting date, application date, and picture date. 

2) Here is an example why conducting meaningful tank-mix research is nearly impossible.  

Grower Tank-Mix Application:

 

My tank-mix application of same treatment: Looks nothing like what grower saw?

3) This ain't starting clean and no way any soil residual herbicide will work on a large, buried pigweed plants!!!! Notice buried stems/roots.  

Palmer Amaranth Control Update (Prostko)

About 2 weeks ago, I put out a small Palmer amaranth control test in Wilcox Co. with John Bennett and Macie Mosteller.  The goal of the test was to investigate potential PPO-resistance.  About 10 minutes after we were done spraying, it rained 0.7".  I went back to the field 2 days later and re-treated in another area of the field.  Here are a few things that we learned:

a) Sometimes the weatherman is correct.  

  

b) Cobra was rain-fast in those 10 minutes (label says 30 minutes) but Gramoxone + Ultra Blazer + Basagran + Dual Magnum was not (need 4 hour rain-free period).  FYI, I have most rain-free periods listed in the comment sections of my various chapters in the 2025 UGA Pest Control Handbook.

c) Applications of Cobra made just 48 hours later were significantly less effective.  In that short time period, average Palmer heights went from 3.54" to 5.05".  Using average heights is NOT a great idea because at both application times 30-50% of the measured plants were larger than the average.

d) Had we and the farmer been in the field 7 days earlier (with no rain), I am certain that a "cracking" application of Gramoxone + Ultra Blazer + Basagran + Dual Magnum would have cleaned up this mess.  TIMELINESS is everything!!!

e) Pretty sure that this population of Palmer amaranth is not PPO-resistant since the 1st application of Cobra was effective.  We also sent some plant samples to the University of Illinois Plant Clinic since they can test for PPO-resistance.  Have not received any results at his time.  

https://extension.illinois.edu/plant-clinic

"Cracking" Time - 2025 (Prostko)

Check out this picture taken from my plots earlier today.  A friendly reminder for peanut growers who need an early-postemergence treatment (aka "cracking" spray) in peanut.  Program can be tweaked according to growers preferences/needs/experiences as follows:

1) Grower can replace Ultra Blazer + Basagran (aka "Georgia Storm") with commercial Storm 4SL @ 16 oz/A.  Storm is a pre-mix formulation of Blazer + Basagran.

2) If grower does not want to use any Ultra Blazer, can just use Basagran 4SL (8 oz/A) or Basagran 5SL (6.4 oz/A).

3) If grower does not want to use Dual Magnum, can use the following:  Anthem Flex 4SE @ 3.0 oz/A; Enversa 3ME @ 48 oz/A; Outlook 6EC @ 16 oz/A; Warrant 3ME @ 48 oz/A; or Zidua 4.17SC @ 2.5 oz/A.  Generally, I have no preference.  When using either Dual Magnum or Outlook in this mix, additional NIS (1 qt/100 gals) is not needed.   

The "Program" Works (Prostko)

Here is a picture taken from my peanut plots earlier this morning.  A friendly reminder that "The Program" really works (starting clean, twin rows, moisture activated residual herbicides) and has been for 28 years of peanut weed control research.

Valor Injury Likely (Again) - Prostko

Valor (flumioxazin) was first registered for use in peanut in 2001.  Since that time, we have observed injury symptoms EVERY year across the state.  Thus, it should no longer be a shock or surprise to anyone when it happens.  The current predicted rainfall events over the next few days will likely result in Valor injury in some peanut fields, particularly in fields where peanuts are cracking.  I do not feel the 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!