For weed control, U.S. corn and soybean farmers rely on chemical herbicides which were applied to more than 95 percent of U.S. corn acres in 2010 and soybean acres in 2012.

Over the course of the last two decades, U.S. corn and soybean farmers have increased their use of glyphosate (the active ingredient in herbicide products such as Roundup) and decreased their use of herbicide products containing other active ingredients.

This shift contributed to the development of over 14 glyphosate-resistant weed species in U.S. crop production areas.

Glyphosate resistance management practices (RMPs) include herbicide rotation, tillage, scouting for weeds, and other forms of weed control.

In some cases, ERS found that usage rates for RMPs increased from 1996 to 2012.

In other cases, RMP use dropped from 1996 to 2005/06 but increased as information about glyphosate-resistant weeds spread.

For example, herbicides other than glyphosate were applied on 93 percent of planted soybean acres in 1996, 29 percent in 2006, and then 56 percent in 2012.

This chart is found in the April 2016 Amber Waves finding, "U.S. Corn and Soybean Farmers Apply a Wide Variety of Glyphosate Resistance Management Practices."