In The Field With Justin Rivers

I have been out in a lot of corn fields over the last week, and one thing I see that is common from field to field is weed pressure. Some were missed on burndown, while others are escapes from a previously applied residual. With the slow growth of the crop, replants, and excessive rains, there will be a need in most fields for an in crop application, and Glyphosate alone will not get the job done.

Luckily, we have quite a few good options in corn to control weeds like marestail, ragweeds, pigweeds and others. There are mainly two site of action groups to consider when we think about post options in corn to control some of these tougher broadleaves, HPPD’s and Growth Regulators( synthetic auxins). In most cases, there will be a need to add other products like glyphosate or atrazine to tank mixes containing these products. Here are the main products to consider and some pros and cons for the two groups….

Group 4 (synthetic auxins)

Product(s)-  Status


–        Great on almost all annual broadleaves, including vines.

–        Quick kill

–        Low volatility risk compared to other dicamba products like Banvel or Clarity

–        Crop Safety


–        Weak on grass

–        Some risk of volatility

–        Less residual activity

Group 27 (HPPD Inhibitors)

Product(s)- Laudis, Callisto, Armezon/Impact


–        Great on most annual broadleaves

–        Most have residual activity

–        Very crop safe

–        With the exception of Callisto, good activity on small grass


–        Weaker on vine species

–        Carryover risk

–        Control of larger weeds

Overall there are many great options in corn. With some of these products, particularly the HPPD’s, the addition of ½ lb of Atrazine will enhance the activity. Be sure to consult the label for adjuvant recommendations as most of these require MSO or COC, or a Non-ionic surfactant. The addition of AMS is also a must in almost all cases.

If you have questions on products, rates, tank mixes or anything else, please don’t hesitate to call.

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