Farm workers in the US weeding cotton fields by hand - this photo in Benbrook's report "The first thirteen years" is not taken on an organic farm, but at the fields of a farmer growing GM cotton. Herbicide tolerant (HT) cotton was heralded as something so easy that one spraying of the herbicide Roundup would solve the weed problem and require less work - a promise that failed even more miserably then most critics would have dared to formulate it 15 years ago.
In his new study, Charles Benbrook analyses the pesticide use of the last 13 years since the introduction of GM crops in the US. He analyzed the pesticide use (herbicides and insecticides) used with HT and Bt maize, cotton and soybean in the US from 1996 to 2008 and compared it with the pesticide use on conventional crops in the same period.
His results are simple: 318 million pounds more pesticides were applied due to the planting of GM crops from 1996 to 2008; about 144 million kg. A reduction in insecticide use on Bt corn and cotton was more then swallowed up by the additional herbicide uses.
Benbrook concludes that the observed increase of pesticide use has mainly two reasons:
- herbicide resistant weed lead to increased and additional herbicide use, including the use of older and more toxic herbicides like paraquat and 2,4-D;
- pesticide use on conventional crops has decreased in the same time, mainly due to the development of lower-dose herbicides.
For the future, he predicts an continuous and sharp increase of herbicide use because more and more GM maize, cotton and soybeans are now sold as 'stacked' varieties containing several GM traits, bringing the Roundup tolerance to even more fields, and continuously dwarfing insecticide reductions of Bt crops.
For Europe this picture would look even more bleak - in most cases maize is not even treated with insecticides so there is no room for insecticide reduction anyway.
144 million kg of pesticides and raising - that's not only bad news for the environment but also for the climate. Agro-chemical production is based on fossil fuels, and according to the IPCC they make up an important part of agricultural greenhouse gas emissions.
Charles Benbrook (2009): Impacts of genetetically engineered crops on
pesticide use: The first thirteen years Published by The Organic