What is Acuron and Shieldex herbicides?

Acuron, from Syngenta, is a mixture of s-metolachlor + atrazine + mesotrione + bycyclopyrone registered for use in field corn, seed corn, silage corn, sweet corn, and yellow popcorn.  Acuron can be applied preemergence or postemergence depending upon the type of corn.  I have tested Acuron for a number of years and it is a very good product.  It would be especially useful to growers who are dealing with glyphosate, atrazine, and/or ALS resistant weeds.  But in the absence of resistance, it’s very difficult to for most higher priced new herbicides to beat the cost-effectiveness of a timely postemergence application of glyphosate + atrazine + Prowl tank-mixture in Georgia.   I do not have an exact figure but I have heard that Acuron is a bit pricey?

Shieldex, from Summit Agro USA, contains the active ingredient topyralate.  Shieldex is labeled for postemergence use in field corn, sweet corn, and popcorn.  Shieldex has the same mode of action as several other corn herbicides such as Callisto (mesotrione), Impact (topramezone), and Laudis (tembotrione).  All of these herbicides are HPPD inhibitors (WSSA MOA #27).  There are 2 good reasons why Georgia corn farmers need not worry about this herbicide:  1) it is not yet labeled in GA; and 2) I only have 1 field trial with this product (i.e. not enough data to make a solid recommendation).