A website from UGA Cooperative Extension

Here is a post by Dr. Eric Prostko discussed the potential problems associated with the the use of Counter and certain postemergence herbicides in field corn.
1) Why can’t certain herbicides be used after an in-furrow (INFR) application of Counter in field corn?

Organophosphate (OP) insecticides, amino acid synthesis (ALS) and certain pigment (HPPD) inhibitors are metabolized in field corn by the same enzyme system (cytochrome P450 monooxygenase).  When these pesticides are used sequentially (INFR + POST) in field corn, this enzyme system cannot successfully metabolize both active ingredients.

2) How bad would corn yields be affected if this accidentally happened?

Research results from 2012 would suggest that yield losses could exceed 40% if an inappropriate herbicide was used following an INFR application of Counter.

Figure 1.  Corn yield response to the interaction of Counter (INFR) and Steadfast (POST).

3) What herbicides can be applied in field corn if Counter is used INFR?

The following herbicides, commonly used in GA field corn production systems, are safe to use if Counter is applied INFR:

Aim, Atrazine, Clarity, Dual Magnum, glyphosate, Impact, Laudis, Liberty, Prowl, Status, Warrant, 2,4-D, and any pre-mix containing these ingredients.

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