Pesticide Action Network Updates Service (PANUPS)
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 U.S. agriculture.
The first comprehensive study of the impacts of all major commercial GE crops on pesticide use in the U.S., "Impacts of Genetically Engineered Crops on Pesticide Use in the United States: The First Eight Years," draws on official U.S. Department of Agriculture data on pesticide use by crop and state to calculate the difference between the average pounds of pesticides applied on the 550 million acres planted to GE crops compared to the pounds applied to similar conventional crops. The study results directly contradict industry claims that GE technology has markedly reduced pesticide use.
In 1996 to 1998, during their first three years of commercial sales, GE crops appear to have reduced pesticide use by about 25.4 million pounds. But in the last three years, over 73 million more pounds of 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 more herbicides on GE acres in order to keep up with shifts in weeds toward 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 trigger ecological changes in farm fields that would incrementally erode the 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 to produce the natural insecticide Bacillus thuringiensis (Bt) in plant cells, has reduced insecticide use by 2 million to 2.5 million pounds 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 reductions of insecticides on acres planted to Bt crops, especially since 2001.
Published by the Northwest Science Environmental Policy Center, the 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.