Will you use Harness, Surpass, Outlook, Dual, or Zidua on your farm? How about SureStart, TripleFLEX, Acuron, Resicore, Anthem Maxx, or Harness Max? Maybe you’ll be spraying Warrant, Warrant Ultra, Halex GT, or Armezon Pro. The one common denominator with all these herbicides?
They all contain a Group 15.
Of the products we sell at Hefty’s, there are more than 70 that contains a Group 15 herbicide. When used at the full rate, all Group 15’s are good on grass and have some activity on small-seeded broadleaves, including waterhemp, Palmer pigweed, kochia, lambsquarters, black nightshade, common ragweed, and even yellow nutsedge. None of them have burndown activity, meaning the only way they control weeds is with their residual. While the residual can last from a few weeks to a few months, carryover to next year’s crops is not really a concern, although a few do have some rotational restrictions.
Below are our comments on each of the four base Group 15 active ingredients.
Acetochlor
This is the active ingredient in Harness and Surpass. These two products are identical. Acetochlor is the most active Group 15 on broadleaf weeds and works with the least amount of rainfall. However, it doesn’t last quite as longin the soil as the other Group 15’s, especially Zidua. Harness and Surpass each contains a corn safener.
Dimethenamid
This is the active ingredient in Outlook. I view this as a middle of the pack in terms of activity on broadleaf weeds, rainfall to activate, and length of control.
Metolachlor
This is the active ingredient in Dual. However, there is metolachlor (old Dual 8E) and S-metolachlor (Dual Magnum). The S-metolachlor is more active, meaning you can use a lower rate. When corn safeners are added to Dual, it becomes Dual II or Dual II Magnum. Dual is the least active Group 15 on broadleaves, and Dual requires more rainfall to control weeds than acetochlor or dimethenamid products. Dual is fairly long-lasting in the soil, just not quite as long as Zidua.
Pyroxasulfone
This is the active ingredient in Zidua. This is the newest Group 15. While it is good on broadleaves, it’s not quite as good as acetochlor. While Zidua takes the most rain to activate, it also lasts the longest, even when you have heavy rainfall.
Here’s a quick synopsis on which Group 15 I typically recommend.
Before I get into this, if you have any specific questions, please e-mail us at radio@agphd.com, because in this short article I obviously don’t have time to go through the good and bad with 70+ products, nor list every option that would be acceptable in each situation. Please note that in parenthesis under each category, I list brand names so you know what is in each premix, but what I mean by each of these is “the active ingredient contained in that brand name”, not the actual brand name.
CORN PRE-EMERGE:
Roundup Ready Corn. Since BASF has almost no Verdict (Outlook plus Sharpen) this year, I will typically recommend TripleFLEX or SureStart pre-emerge. Both contain Harness/ Surpass, as well as Stinger and Python to help out on broadleaves. This is an inexpensive way to start, although it is using only a reduced rate of Group 15.
Non-Roundup Ready Corn. Use the full rate of a Group 15 if you don’t have Roundup as a rescue option because in conventional corn the only good grass-killer post is Accent, which is expensive and isn’t great on grasses bigger than two inches tall. Since all Group 15’s are about equal on grass, use whichever one you want.
CORN POST-EMERGE:
As long as your rotation allows it, I almost always recommend an HPPD product post-emerge, rather than pre. If you want more Group 15 residual, the premixes containing an HPPD include Resicore (Surpass, Stinger, Callisto), Acuron (Dual II Magnum, atrazine, Callisto, and another HPPD), and Harness Max (Harness and Callisto).
SOYBEAN POST-EMERGE:
I don’t love Group 15’s pre-emerge in soybeans, as I would rather see you use a yellow (Trifluralin or Prowl), but post-emerge, Group 15’s offer great residual and activity on some of the toughest Roundup-resistant weeds. I like Warrant Ultra (unsafened Harness plus Flexstar) best due to longer residual with the Flexstar, but Anthem Maxx (Zidua plus Cadet) is also good.