A website from UGA Cooperative Extension

Per Dr. Prostko:

Peanut growers should be seriously thinking about beginning their POST herbicide applications as early as 30 DAP.  Some peanut growers will choose to use Cadre (imazapic).  Others may not want to use Cadre due to crop rotation/carryover concerns.  Here are a few things to consider:

1) Growers who will be using Cadre need to consider the fact that much of the Palmer amaranth in Georgia is resistant to the ALS-inhibiting herbicides.  Thus, it’s a a a good idea to tank-mix Cobra (lactofen) or Ultra Blazer (acifluorfen) with Cadre to address this particular issue. If Cobra or Ultra Blazer are not included, it will be too late to control those pigweeds once a grower discovers that they are ALS-resistant.  

2) If a grower cannot use Cadre, then Cobra or Ultra Blazer are the best options for pigweed.  When pigweed plants are small (2″-4″), there is not much difference in control between Cobra or Ultra Blazer.  However, Cobra is more effective on larger weeds (>4″).  But, Cobra will cost about ~$9/A more than Ultra Blazer.  It is important to remind growers that if Cadre is not used in peanut, it is very likely that yellow/purple nutsedge and sicklepod/coffeeweed will be a problem.  

3) If sicklepod is also present in the field, Butyrac (2,4-DB) should be included in the tank-mix. I recently heard from a grower in Middle Georgia that there was a rumor floating around that I only recommended 12 oz/A of 2,4-DB in peanuts.  To set the record straight, I recommend the use of 12 oz/A of 2,4-DB, if needed, when it is tank-mixed with Gramoxone (paraquat) + Storm (bentazon + acifluorfen) + Group 15 when applied early-postemergence (i.e. cracking spray).  I usually recommend 16-24 oz/A of 2,4-DB when it is applied POST with Cadre or Cobra or Ultra Blazer.  

4) Because pigweed and annual grasses are such a problem in most peanut fields, it’s also a good idea to think abut including a Group 15 herbicide that will provide additional residual control of these weeds.  Group 15 herbicides include the following: Anthem Flex (pyroxasulfone + carfentrazone), Dual Magnum (S-metolachlor), Outlook (dimethenamid-P), Warrant (acetochlor), and Zidua (pyroxasulfone).  Not much difference in weed control between the Group15 herbicides but Anthem Flex and Zidua have provided slightly better residual control of Texas panicum in my research trials over the years.

5) When Dual Magnum or Outlook are included in POST tank-mixtures, additional adjuvants are not recommended because these are EC (emulsifiable concentrates i.e. oil-based) formulations.  NIS (0.25% v/v) is recommended if any of the other Group 15 herbicides are used since they are not EC formulations. 

6) Check out Figure 1 below.  These pictures were taken from my plots on June 3, 2024.   Since the Palmer amaranth population at this location is ALS-resistant, I am getting much better control with the Cadre + Cobra or Ultra Blazer tank-mixes. 

7) Note that I have included the estimated prices/A for each of these treatments.  These are average prices that I have obtained from several dealers so they will very likely be slightly different for every grower.   

Figure 1.  Weed control in peanut with Cadre/Cobra/Ultra Blazer/2,4-DB/Dual Magnum tank-mixtures in peanut, UGA Ponder Research Farm, Ty Ty, GA, June 3, 2024.

Posted in: