Peanut Weed Control Update (Prostko)

 1) A few pictures from my peanut weed control plots taken earlier today. Further proof that UGA recommended programs work when applied in a timely manner.  

2) Growers who do not like Sonalan can use Prowl.  Growers who do not like Dual Magnum can use one of the following: Anthem Flex, Enversa, Outlook, Warrant, Zidua.  Growers who do not like Basagran can use Storm or make their own "Georgia Storm" (Ultra Blazer @ 16 oz/A + Basagran 5SL @ 6.4 oz/A).  Growers who do not like Cobra can use Ultra Blazer. Growers who do not want to use Cadre are likely to see less control of sicklepod and nutsedge (sorry but that's the truth!).

3) For growers who did not get their PRE herbicides applied, there is hope!

4) I have heard thru the grapevine that Ultra Blazer is short or non-existent in GA at this time. I have also heard that there was about 11,000 gallons of Cobra in a Valdosta warehouse last week.  So growers who are told that there is no Cobra, need to think about shopping elsewhere!

5) I have been getting lots of questions about Benghal dayflower.  It thrives in wet weather! Also, Benghal dayflower will be worse in peanut fields planted after May 15 and into June. The key to controlling this weed is moisture activated residual herbicides (Group 15's).  I have no preference but we do have more data with Dual Magnum simply because the other Group 15 herbicides (Anthem Flex, Enversa, Warrant, and Zidua) were not on the market way back then.  Outlook has been around for awhile but was always the Group 15 red-headed step child for various reasons until recently (labeled for peanut in 1999).

Questions and Answers from Today: Field Corn, Grain Sorghum, Soybean, Peanut (Prostko):

This morning was an interesting day for various weed science related questions on multiple crops (field corn, sorghum, soybean, peanut).  Since most questions are common to all (sooner or later), I thought I would share:

Question#1: How much Dual on Concep treated sorghum would it take before you would start seeing damage? 

Answer#1: Probably would need to be above 2.5 pts/A on our soil types before you would start seeing significant injury.  Research from Kansas State University a few years ago would suggest that what would be the equivalent of 4 lb ai/A of Dual Magnum (4.2 pts/A) did not cause major yield losses when Concep treated sorghum seed was planted.  

Check out this 1992 publication from Kansas State University:

https://extension.k-state.edu/historicpublications/pubs/SB659.pdf

Dual Injury Pictures on grain sorghum:

Figure 1.  Dual injury on grain sorghum (https://grdc.com.au/__data/assets/pdf_file/0029/627914/avoid-metolachlor-damage-in-sorghum-grdc-20251003.pdf)

Question#2: Is this herbicide injury on field corn?

Figure 2.  Magnesium deficiency on corn (A. Smith)

Answer#2: No, this is not herbicide injury. Most likely a magnesium deficiency which can be confirmed via a leaf tissue test.

Question#3: I have a peanut field that rain kept us from spraying behind planter.  No herbicides have been applied. What do you suggest?

Answer#3: If peanuts are less than 28 days after cracking:  Gramoxone 3SL @ 8 oz/A + Ultra Blazer 2SL @ 16 oz/A + Basagran 4LC @ 8 oz/A + Zidua 4.17SC @ 2.5 oz/A or Anthem Flex 4SE @ 3 oz/A + NIS @ 32 oz/100 gals (0.25% v/v).  Zidua or Anthem Flex would be preferred in this situation because they both contain pyroxasulfone which is slightly better on Texas panicum than the other Group 15 herbicides (Dual Magnum, Enversa, Outlook, Warrant) and neither Prowl nor Sonalan was applied.

Question#4: Can I apply Prowl over the top of soybeans (V5) at 16 oz/A?  

Answer#4:  Prowl is NOT labeled for postemergence (POST) use in soybean. When applied POST, I have seen it cause galling at the soil surface which can result in stem breakage later in the year.  NO Bueno!  Group 15 herbicides can be used.    

Question#5:  I have peanuts that are now 33 DAP that have mostly nutgrass but some escaped pigweeds and sicklepod.  I am assuming the pigweeds are ALS-resistant but they are 2-3" tall while nutgrass is pretty thick in places.  Would it not be best to spray Cadre + 2,4-DB + Dual and hope the 2,4-DB takes out the small pigweed?  I don't want the nutgrass taking over.

Answer#5: 2,4-DB is not very effective for pigweed control when tank-mixed with Cadre but it does help with other weeds such as sicklepod and morningglory.  In this case, I would suggest the following:  Cadre 2SL @ 4 oz/A + Cobra 2EC @ 12.5 oz/A or Ultra Blazer 2SL @ 24 oz/A + Dual Magnum 7.62EC @ 16 oz/A + 2,4-DB 2SL @ 16 oz/A.  Other Group 15 herbicides (Enversa, Outlook, Warrant, Zidua) can be used in place of Dual Magnum if desired.

Question#6:  Can I use Basagran + Dual Magnum for Benghal dayflower/tropical spiderwort control in peanut and should I add a crop oil to this mixture?

Answer#6:  Yes, Basagran 4LC @ 32 oz/A + Dual Magnum 7.62EC @ 16 oz/A is a very effective treatment for dayflower species.  Additional crop oil is not needed because the Dual Magnum is an EC (oil-based) formulation and has adjuvant-like properties.  

Figure 3.  Spreading dayflower control in peanut with Broadloom (generic Basagran) and Dual Magnum with no additional COC.