By Brian Hefty

It wasn’t many years ago when this article could be summarized in one word on many farms: Roundup.  Unfortunately today, Roundup may not be controlling all your waterhemp, Palmer pigweed, lambsquarters, common ragweed, giant ragweed, kochia, or marestail.  Did I miss one?

Roundup is still great on most annual grasses, but if you want broadleaf control, you will likely need something else.  Also, there are a lot of farmers who are now using their pre herbicide in an early post application with the hope that one shot will stop everything.  I will probably never fully buy into that idea because if you spray even 3 days too late, you may have lost 5 bushels in yield.  If there are weeds that come up after that early application, those could either hurt yield or just increase your weed seed bank for the future.  I have always found that 2 applications maximizes yield and keeps the weed populations lowest, but if you want to try one-pass, that’s obviously your call.  Below are the best options for both situations, pre and no pre.

Best Roundup Tankmix Partners:

  • Status – Diflufenzopyr plus a little dicamba – This is my favorite post-emerge product in corn because of its broad weed spectrum.  Status can control almost any broadleaf better than any other herbicide.  It has some residual, but not so much that carryover will ever be an issue.  Status is also great because of its corn safener.  Even though the label allows you to spray bigger corn due to the safener, we still like to see Status applied by V5.  The biggest downfall to Status is it is higher-priced than straight dicamba or an HPPD.
  • HPPD – Sure, Bellum (generic Callisto) is cheap upfront, but there are rebates with Impact and Laudis (depending on additional products you may buy) that can actually make them less expensive than Bellum.  There are some other minor differences between HPPDs, including crop safety and weed spectrum, but they are all pretty similar.  It is because of this similarity that I occasionally mix them up myself.  For example, in last month’s newsletter I need to give you 2 minor corrections.  Corvus is Varro plus Balance Flexx (not Laudis as I mistakenly said), and Balance Pro is no longer produced by Bayer, it is Balance Flexx.  These HPPD products have all come WAY down in price over the last 12 months, so regardless of the product you choose, it will be economical.  The biggest weaknesses we see with HPPDs are potential resistance if they get overused, long rotational restrictions to a few specialty crops, and less activity than Status or dicamba on wild buckwheat and thistles.
  • Dicamba – Banvel and Clarity have been out forever, and they still work pretty well on most weeds.  Sure, they’re not as good as Status, but they are cheaper.  The two things people have really not cared for with Banvel and Clarity over the years have been drift and crop injury.  If you are going to mix Banvel or Clarity with Roundup, we suggest you spray by V2 if at all possible to practically eliminate crop injury risk.  There is also DiFlexx, which is Clarity plus a safener, if you want to spray after V2.  In terms of drift, you just have to spray when the wind is pretty calm, but there is no way to escape the volatility these products can have.  While not overly common, Banvel and even Clarity to some degree can pick up and move a few hours after application.  To solve this problem almost entirely, you can invest an extra $2 to $4 (depending on your tankmix rate) in Engenia or Xtendimax.  I know those products are thought of as soybean herbicides for Xtend beans, but they are labeled for corn, they are just as effective as Clarity and Banvel, and they have dramatically less volatility risk.

Best One-Pass Early Post Products:

  • Acuron Flexi – This is a new combination of Callisto, bicyclopyrone (a new HPPD), and Dual.  Adding the second HPPD seems to broaden the weed spectrum a little bit, as we are seeing better results on wild buckwheat, for example.  Like each of the other products in this category, Acuron Flexi can be used pre or early post.  Most people will mix a glyphosate with Acuron Flexi, but it could be used without glyphosate if you have almost no emerged grass.
  • Resicore – This product contains the active ingredients found in Surpass (same as Harness), Stinger, and Callisto.  Having 3 modes of action with broadleaf activity is nice, but just like with Acuron Flexi, it struggles with emerged grass and could use a glyphosate tankmix partner if that’s a concern.
  • TripleFLEX – This combination of Harness, Stinger, and Python has been out for quite a few years.  It is the cheapest of all these options, but Python is an ALS herbicide, so that component won’t help you on ALS-resistant weeds.  On most of the Roundup-resistant weeds, all the other choices are better, but they are also more expensive.
  • Halex GT – This product has also been out for several years.  Its big advantage is it already contains glyphosate, to go along with Callisto (mesotrione) and Dual.  While Halex is still an excellent herbicide on most weeds in an early post situation, it now has good competition from Resicore and Acuron Flexi, as they each contain mesotrione, too.

Which product would I pick?  It all depends on your weed spectrum and weed pressure.  All 7 of the products (or product categories) I listed above are sound, and I would feel comfortable applying any of them on my farm using the guidelines I laid out above.