Iowa State University

Yesterday's Herbicides   
by Bob Hartzler

March 3, 2008 - After a long hiatus, an herbicide manufacturer has finally introduced an advertisement worthy of The Herbicide Ad Hall of Shame. The ad promotes three of DowAgroSciences ‘new’ products, claiming that you 'shouldn’t let yesterday’s herbicides slow you down'. As nearly everyone is aware, most new herbicide products aren’t really new, but merely old active ingredients repackaged*. None of the active ingredients in these Dow products is less than 15 years old (Table 1). Thus, the first strike against this ad is that it provides misleading information.

Table 1. Age of active ingreadients in new DowAgrosciences products.

The second strike is the negative portrayal of ‘old’ herbicides. In this era of heavy reliance on glyphosate, herbicides with different modes of action are our primary line of defense against the rapid selection of glyphosate resistant weeds. While there is no doubt that, when compared to glyphosate, none of these ‘old’ products are as effective or have as large a margin of crop safety; however, they still are extremely effective weed management tools. Thus, the only thing these herbicides slow down is the evolution of glyphosate resistance.

Fortunately, I couldn’t find a third strike for the ad, but two is sufficient for the Hall of Shame.

* Marshall McGlamery, retired Extension Weed Scientist at the University of Illinois, coined the phrase "can 'em and confuse 'em" for this practice a long time ago.

Prepared by Bob Hartzler, extension weed management specialist, Department of Agronomy, Iowa State University