By Brian Hefty

When I was a young agronomist over 25 years ago, it was easy making a recommendation to corn farmers.  Would you like to use old Lasso pre-emerge or go with Dual or Eradicane?  Post-emerge, the only question was if the farmer was willing to switch from a 2,4-D/Banvel mixture to Buctril-Atrazine.  Today, you have so many more choices, and the best news is many of the choices have great agronomic benefits.

Focusing on the pre-emerge herbicides, there is one big question that only you can answer.  Is your biggest issue grass or broadleaves?  For the most part, Roundup is still excellent on grass.  In other words, if your pre is a little weak on grass in Roundup corn, it’s no big deal – the Roundup will clean up any remaining grass.

On the other hand, if you have a severe grass problem or if you are raising conventional corn, you need a pre that has fantastic grass control.  Here are the best grass products along with a couple of comments about each.

CORN GRASS PRE-EMERGE HERBICIDES (with some broadleaf activity):

  • Harness or Surpass – Our experience has shown these work with the least amount of moisture, but they may also run out the soonest in extremely wet situations.  These products are also the best on small-seeded broadleaves, but Harness and Surpass are restricted use herbicides.
  • Outlook and Dual – These products are labeled for both corn and soybeans, and they are commonly used pre or early post to extend residual.  While slightly weaker on small-seeded broadleaves, these herbicides are just as good on grass as anything else on this list.
  • Zidua – Since the other grass herbicides are all 20+ years old, I sometimes forget to even mention Zidua, as it just came out in the last few years, and it isn’t as popular as the other choices.  Like every other product on this list, Zidua is a Group 15, but it is the least water-soluble product of the group.  This could mean longer residual in very wet conditions, which is why Zidua is a great choice in the eastern Cornbelt.

If you have Roundup corn or if you for some reason have little to no grass pressure, using a product that it is better on broadleaves than grass is probably a good way to go with your pre-emerge corn herbicide.  The thing is, there aren’t many single product broadleaf herbicides.  What you will usually get is a premix, which I note in the next section.

CORN BROADLEAF PRE-EMERGE HERBICIDES (with some grass activity):

  • Balance Pro (which I will refer to as Balance) has been out for years, but this year the price has come down.  Balance has good small-seeded broadleaf activity (kochia, waterhemp, Palmer pigweed, lambsquarters, etc.) and suppression on some large-seeded broadleaves.
  • SureStart or TripleFLEX – This contains the active ingredients (a.i.) from Surpass, Python, and Stinger.  This has been the most popular setup product for Roundup due to its low price.  However, if you have a severe broadleaf issue, there are certainly better options for weed control.
  • Verdict – Verdict contains the a.i.’s from Outlook and Sharpen.  While we like the small-seeded broadleaf activity and the burndown on broadleaves the Sharpen provides, Verdict is much higher-priced and it can only be used before the corn emerges.  Verdict can be used in soybeans also, but only at a lower rate.
  • Corvus – Corvus has the a.i.’s from Varro and Laudis.  The problem we have with Corvus is if your main weeds are ALS-resistant.  Since Varro is an ALS, that would leave only Laudis as your pre broadleaf product, meaning you shouldn’t use any HPPD post.
  • Acuron Flexi – this has the new bicyclopyrone (HPPD), along with the a.i.’s from Callisto and Dual.  We strongly encourage you to avoid straight Acuron pre-emerge, as it contains atrazine.  We really worry about atrazine ending up in groundwater, so the safer way to use it is post-emerge.  Acuron Flexi is cheaper than Acuron, and it can be used pre or post.
  • Resicore – when you put the a.i.’s together from Surpass, Stinger, and Callisto, you’ve got a powerful combination.  Resicore is inexpensive, can be used pre or post, and it has 3 different modes of action that all have activity on many of the toughest Roundup-resistant weeds.

The crazy thing about this article is I left off a bunch of other pre-emerge products that could fit in certain situations.  The ones I included are the ones I typically recommend, and the ones I feel bring the best value for most farmers.  If you have a question about the product you are using, please call our radio show at 844-442-4743 or e-mail us at  We would love to talk to you and help you get the best product for your fields.