A November 2003 study of levels of
pesticide use on genetically engineered (GE) corn, soybeans and
cotton in the U.S. reports that these GE varieties have resulted
in the application of more pesticides.
While use of Bacillus thuringiensis (Bt) transgenic varieties
have reduced pesticide use by an estimated 19.6 million pounds
in the past eight years, herbicide tolerant crops have been responsible
for the application of an estimated 70 million additional pounds
of pesticides. Overall, the report concludes that GE crops have
caused 50 million additional pounds of pesticides to be used in
The first comprehensive study of the impacts of all major commercial
crops on pesticide use in the U.S., "Impacts of Genetically
Crops on Pesticide Use in the United States: The First Eight Years,"
draws on official U.S. Department of Agriculture data on pesticide
crop and state to calculate the difference between the average
of pesticides applied on the 550 million acres planted to GE crops
compared to the pounds applied to similar conventional crops.
results directly contradict industry claims that GE technology
has markedly reduced pesticide use.
In 1996 to 1998, during their first three years of commercial
crops appear to have reduced pesticide use by about 25.4 million
pounds. But in the last three years, over 73 million more pounds
pesticides were applied on GE acres. Substantial increases in
herbicide use on herbicide tolerant (HT) crops, especially soybeans,
accounted for the increase.
Herbicide tolerant (HT) crops allow farmers to spray broad-spectrum
herbicides over the top of growing plants, controlling weeds while
leaving crops unharmed. Despite the increased costs of GE seeds,
herbicide tolerant crops have become less expensive as the price
of herbicides containing glyphosate has fallen by half, from around
$12.00 per acre when HT crops were first introduced to less than
$6.00 per acre today.
The report finds that many farmers need to spray incrementally
herbicides on GE acres in order to keep up with shifts in weeds
tougher-to-control species, coupled with the emergence of genetic
resistance in certain weed populations. "For years weed scientists
have warned that heavy reliance on herbicide tolerant crops would
ecological changes in farm fields that would incrementally erode
technology's effectiveness. It now appears that this process began
in 2001 in the U.S. in the case of herbicide tolerant crops,"
said Dr. Charles Benbrook, author of the report.
The other major category of GE crops, corn and cotton engineered
produce the natural insecticide Bacillus thuringiensis (Bt) in
cells, has reduced insecticide use by 2 million to 2.5 million
annually. This reduction represents 7% of the total U.S. insecticide
use on these two crops. The report notes that the increase in
herbicide use on HT crop acres, however, far exceeds the modest
insecticides on acres planted to Bt crops, especially since 2001.
Published by the Northwest Science Environmental Policy Center,
report received support from a number of organizations concerned
about the impacts of GE crops on the environment and human health.
Dr. Benbrook, Executive Director of the Northwest Science and
Environmental Policy Center in Sandpoint, Idaho, was formerly
with the National Academy of Sciences Board on Agriculture.
The full report is available on Ag BioTech InfoNet website at
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