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Issue No. 5, Article 2/April 24, 2009

Pay Close Attention to Product Names and Formulations

Over the years herbicide manufacturers have introduced many new herbicide products and formulations into the marketplace. Recently, new herbicide premixes and formulations of existing active ingredients have outpaced the introduction of novel active ingredients. Herbicide chemical, active ingredient, and trade names have been discussed in previous issues of the Bulletin, but here we briefly revisit an important aspect of herbicide trade names and formulations.

Planting conditions thus far in 2009 have been much less than ideal across most of Illinois. When fields conditions improve, we anticipate most all planting-related activities will commence at an accelerated pace. Many acres to cover in a relatively short period can lead to very long days in the rush to finish planting. Attention to details can be diverted during these busy intervals, but how might this lead to future problems with herbicides and weed control?

A brief examination of names of herbicides currently on the market demonstrates that several active ingredients are marketed under more than one trade name/formulation. For example, the active ingredient isoxaflutole is marketed as Balance Pro and Balance Flexx. Even though the active ingredient in the two products is identical and the trade names are very similar, several important differences between the products mean that their use patterns are not necessarily interchangeable.

One important difference is the amount of active ingredient in the formulated product; Balance Pro contains 4 pounds of active ingredient per gallon, whereas Balance Flexx contains only 2 pounds of active ingredient per gallon. Another very significant difference is that Balance Flexx, formulated with a safener to reduce the potential for corn injury, can be applied after corn has emerged (up to V2 corn), but Balance Pro must be applied before corn emergence or severe corn injury will result. In the heat of the planting season, inadvertently applying Balance Flexx at the Balance Pro application rate would result in only 50% of the desired rate of active ingredient being applied, potentially leading to less weed control than desired. Inadvertently applying Balance Pro instead of Balance Flexx after corn emergence will result in a less-than-desired corn response.

Table 1 provides a partial list of herbicide products that have similar or identical names but different formulations or components. When possible for products containing the same active ingredient, application rates are provided that would result in the application of a similar amount of active ingredient. For example, Accent and Accent Q both contain nicosulfuron, but Accent Q contains less per unit of formulated product, so a higher rate of Accent Q (0.92 ounce) must be applied to get the same amount of nicosulfuron applied at a lower rate of Accent (0.67 ounce).

Other differences among the various products also become apparent. Resolve DF and Resolve SG are different formulations of rimsulfuron that contain the same amount of active ingredient per unit of formulated product, so application rates are identical. However, while Resolve Q also contains rimsulfuron, it has thifensulfuron as well. Both Flexstar and Flexstar GT can be applied postemergence to glyphosate-resistant soybean varieties, but only Flexstar can be applied to non-GMO soybean varieties.

Time is extremely valuable at this time of year, but taking a little extra to make certain you are using the appropriate product and formulation can be time extremely well spent.--Aaron Hager

Aaron Hager

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