One of the main reasons for the development of glyphosate resistant horseweed and Palmer amaranth in the U.S. is the fact that a large portion of crop acres are treated with glyphosate. This chart provides an illustration on the use of glyphosate in corn, cotton, and soybean from 1996 to 2003. The significant increase in glyphosate use in cotton and soybean over the past several years can be attributed to the rapid adoption and utilization of “Roundup Ready” crop varieties. Soybean data for 2003 was unavailable.

U.S. Acres Treated with Glyphosate 1996-2003 <BR>Source: USDA - National Agricultural Statistics Service – Agricultural Chemical Usage Reports<BR>