As an ag retailer, I am always looking at different active ingredients and modes of action to help prevent weed resistance in my customers’ fields. Overall, we do a good job rotating preemergence programs each year despite few new active ingredients being released. However, when we look at our entire chemical program including burndown, preemergence and post emergence applications, I think there is room for improvement in managing our post emergence residual chemistries. To be clear, I’m talking about the residual we are putting in the tank with our Liberty (Glufosinate) and Enlist One (2,4-D Choline). Obviously, your herbicide tolerant soybeans will dictate which contact herbicide you post apply, however we will still be using the same Group 15 herbicides residual options. The most popular Group 15 herbicides active are S-Metolachlor and Metolachlor. Brand name and generic examples of S-Metolachlor (S-isomer) products would be Everprex, Cinch or Moccasin II Plus. Examples of Metolachlor products would be Metalica, Priority 8E and Stalwart C to name a few. Whether brand name or generic, these Group 15 residual herbicides are widely used in both preemergence and post residual applications. They are the most cost-effective Group 15 on the market. The question is are they still the most effective? Similar to my previous blog entitled “Is Mesotrione Losing Its Luster”, I believe we are seeing similar inconsistent control with S-Metolachlor and Metolachlor. This past season we saw instances where we controlled grasses but failed to consistently control broadleaves. Perhaps we are just dealing with environmental issues as opposed to resistance, but it’s enough to warrant changing up some of our residual plans for 2026.
So what other Group 15 products should we be looking at in 2026? On option might be the Warrant herbicide from Bayer. Warrant is a Group 15 with the active ingredient acetochlor. Warrant is formulated as a microencapsulation that provides extended residual control of weeds while providing additional crop safety. Bayer also utilizes this microencapsulated acetochlor in their corn herbicide, Degree Xtra. Generic chemical manufacturer, Sharda, also has an encapsulated acetochlor product called Arrest CS. This encapsulation technology also allows for a more gradual release of the active ingredient and provides better crop safety. We are going to look at utilizing an encapsulated acetochlor with our customers to switch things up without breaking the bank.
Another Group 15 herbicide that we will use is Outlook herbicide from BASF. The active ingredient in Outlook is dimethenamid-P. One thing I really like about Outlook is that it only takes .25” of rain to activate this herbicide. S-Metolachlor and Metolachlor require at least .5” of rain to fully activate. Depending on the post application timing, I’ve seen spring rains wane and the difference on whether our residuals activate or not was .25” of rainfall. Additionally, Outlook has excellent crop safety and a low use rate. I would consider Outlook middle of the pack from a price standpoint.
The last Group 15 herbicide I’m going to mention is the active Pyroxasulfone. This active is found in Zidua SC from BASF and in Anthem Max from FMC Corp. Zidua SC is a straight goods Pyroxasulfone while Anthem Max contains both Pyroxasulfone and Cadet (Group 14). The Pyroxasulfone active ingredient provides superior residual control that can last up to two weeks longer than S-Metolachlor/Metolachlor. From a pricing standpoint, Pyroxasulfone is what I’d call the Cadillac when it comes to residual programs, however, if you are looking for the best residual control in the marketplace, this single active is currently it. To my knowledge the active, Pyroxasulfone is off-patent. Speculation is we will see a generic Pyroxasulfone, pending regulatory approvals, introduced into the market-place. For now, it’s a stay tuned topic. I do believe once we see a generic Pyroxasulfone product, we will see more growers make the switch to this active as the generic version should be more cost-effective.
As we look at post residual options, I think we need to start by looking at our entire chemical plan. For example, if we are planning on using Tendovo (Cloransulam, Metribuzin, S-Metolachlor) as our preemerge soybean herbicide, we need to be aware this product contains the Group 15 active S-Metolachlor. As we look to layer our residuals with our post application, it would make sense to look at a different Group 15 residual such as Outlook, Pyroxasulfone or an encapsulated acetochlor. It just makes sense to switch it up. I will be challenging the growers I work with to think through their entire chemical plan especially when it comes to our residual herbicides. For more information including tech sheets, labels and sds sheets check out our site. Thanks for reading our blog.
-Brian
(Note: The patent for Pyroxasulfone was issued on February 12, 2012 which put the 10-year data protection expiration date at February 12, 2022. The EPA did grant a three-year extension which did expired on February 15, 2025).
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