What did you say is in that premix? How much of each component do I get at this application rate? If I apply this premix at a higher rate, am I still within my atrazine application limits?
If you ever have asked yourself (or others) these types of questions, the tables accompanying this article may be beneficial in preserving your good-natured character. While the introduction of novel herbicide active ingredients has slowed considerably over the past few years, new herbicide pre-mixes are introduced almost yearly. It can be difficult to remember what each premix is composed of and how much of each component is contained within the premix. Table 3 lists many of the corn herbicide premixes used in Illinois, while Table 4 is a similar listing of soybean herbicide premixes. Let's examine the information contained within these tables in a little more detail.
The first column lists the commercial or trade name of the herbicide and its formulation. The commercial or trade name is the name most familiar to folks. Another list of names (arguably less familiar than the names in the first column) appears in the second column; these are the common names for each herbicide component of a premix. For example, in Table 3 we see that Axiom (trade name) 68DF (formulation) is composed of the active ingredients flufenacet (common name) and metribuzin (common name). Common names are useful because they always refer to the same active ingredient; trade names don't always refer to the same active ingredient. Think back a few years to a herbicide with the trade name Option; this product contained the active ingredient fenoxaprop (common name) and was used for postemergence control of grass species in soybean. The Option (trade name) herbicide now on the market contains foramsulfuron (common name) and is used for postemergence control of grass species in corn. Needless to say you do not want to apply fenoxaprop to corn or foramsulfuron to soybeans, hence the benefit of knowing herbicide common names.
The third column lists an application rate for each premix. We tried to select application rates that were representative for Illinois, but you may want to select a different rate and redo the calculations in the fourth and fifth columns. The fourth column indicates how much of each active ingredient is applied at the rate listed in the third column. Going back to the example of Axiom, we see that 19 ounces of Axiom provides 0.646 pound flufenacet active ingredient and 0.162 pound metribuzin active ingredient. Note here that, while rates of commercial products are usually expressed in ounces, pounds, pints, quarts, and so on of product per acre, active ingredients are usually expressed in units of pounds of active ingredient or acid equivalent per acre.
Finally, the last column lists product equivalents for each premix component when applied at the rate listed in the third column. So the 19-ounce rate of Axiom provides the same amount of flufenacet and metribuzin that is contained in 17.23 ounces of Define 60DF and 3.45 ounces of Sencor 75DF, respectively.--Aaron Hager and Christy Sprague