Herbicide use on roundup ready crops.

In his News Focus article "GM crops in the cross hairs" (26 Nov., p. 1662), Dan Ferber refers to the assessment by Charles Benbrook of the effect that the introduction of Roundup Ready crops has had on herbicide use, concluding that the benefits are not clear-cut. We disagree with this conclusion. Changes in herbicide use are largely meaningless unless relative environmental and health risks are taken into consideration, and Benbrook notes the more benign nature of Roundup compared with other herbicides. According to Ferber's article, Benbrook found that farmers apply two to five times more herbicide to Roundup Ready acreage than to conventional soybeans. However, an examination of herbicide use data does not seem to support this finding.