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.