Crops that have been genetically modified (GM) to be tolerant to herbicides have been widely grown in the U.S. since 1996.
Evidence shows that use of the technology has resulted in a net reduction in both the amount of herbicide used and the associated environmental impact when compared to what can reasonably be expected if the area planted to GM HT crops reverted to conventional production methods. It also facilitated many farmers being able to derive the economic and environmental benefits associated with switching from a plough-based to a no tillage or conservation tillage production system.
The technology has also contributed to a change in the profile of herbicides used. A broad range of, mostly selective herbicides has been replaced by one or two broad-spectrum herbicides (mostly glyphosate) used in conjunction with one or two other (complementary) herbicides. Since the mid-2000s, the average amount of herbicide applied and the associated environmental load have increased on both GM HT and conventional crops as a result of increasing incidence of weed species developing populations resistant to herbicides and increased awareness of the consequences of relying on a single or limited number of herbicides for weed control.
Read full, original article: Weed control changes and genetically modified herbicide tolerant crops in the USA 1996–2012