(Beyond Pesticides, November 7) Once heralded as a breakthrough for reducing the rates and toxicity of the pesticides applied by farmers, genetically engineered (GE) crops are perversely leading to renewed dependency on the very herbicides they were claimed to make obsolete. Growing recognition that pervasive planting of â€śRound-Up Readyâ€ť corn, soybeans and cotton is accelerating weed resistance is prompting GE seed companies to rush to market ‘stacked’ varieties that are resistant to additional herbicides, including 2, 4-D and dicamba. Farmers planting the stacked varieties will be spraying these older herbicides in addition to glyphosate, which most commodity crops have already been engineered to tolerate. Professor David A. Mortensen of Pennsylvania State University has estimated that adoption of Round-Up Ready and 2, 4-D or dicamba resistant stacked varieties in soybeans could result in a 70% increase in herbicide use in a relatively short time.
The St. Louis Pots-Dispatch reported on progress that multinational chemical corporations Dow AgroSciences, BASF, and Monsanto are making to bring multi-herbicide resistant varieties to market. Under separate arrangements with each company, Monsanto adds glyphosate resistance to seeds that are simultaneously engineered to resist other herbicides. In October, Dow AgroSciences obtained a global patent on its Enlist Duo technology, which packages an herbicide containing 2, 4-D and glyphosate with seeds engineered to tolerate both materials. Commercial release of an Enlist Duo corn variety is anticipated for 2013 with similarly engineered soybeans projected to become available in 2015.
2, 4-D is a highly toxic chemical which has been linked to cancer, reproductive effects, endocrine disruption, and kidney and liver damage. It is also neurotoxic and is toxic to beneficial insects (such as bees), earthworms, birds, and fish. Scientific studies have confirmed significantly elevated rates of non-Hodgkinâ€™s lymphoma for farmers who use 2, 4-D.
Monsanto has been partnering with BASF on dicamba and glyphosate tolerant crop varieties since 2009 with a focus on soybeans, cotton, and corn. Commercial release of engineered seeds for these crops is projected for the mid-point of this decade. Dicamba is a neurotoxic chlorinated benzoic acid herbicide that the Environmental Protection Agency classifies as acute toxicity class III, slightly toxic. The material is a recognized eye irritant, moderately persistent in the environment and highly mobile in both soil and water. Chronic exposure is linked to reproductive and developmental effects.
Concern about an impending spike in 2, 4-D and dicamba usage is exacerbated by the timing of the applications for the new herbicides that combine these materials with glyphosate. These new blended herbicides will be sprayed repeatedly during the growing season after weeds emerge and begin to compete with crops. Both 2, 4-D and dicamba are highly susceptible to drift and dicamba is known to volatilize (evaporate) and travel upwards of two miles from the point of application. The spraying of more 2, 4-D and dicamba during periods when specialty crops and home gardens are at their greatest risk of exposure is likely to increase the incidence of pesticide contamination and resultant damages.
GE crops have also yet to deliver on the early promises made by the biotechnology industry to increase crop yields. A recent report from the Union of Concerned Scientists evaluated the overall effect genetic engineering has had on crop yields in relation to other agricultural technologies. It reviewed two dozen academic studies of corn and soybeans, the two primary GE food and feed crops grown in the United States. The report concludes that GE herbicide-tolerant soybeans and herbicide-tolerant corn has not increased yields. Insect-resistant corn, meanwhile, has improved yields only marginally. The increase in yields for both crops over the last 13 years, the report finds, is largely due to traditional breeding or improvements in agricultural practices.
Farmers do not have to remain stuck on a pesticide treadmill that demands ever greater amounts of synthetic inputs and rewards chemical suppliers at the expense of farm profitability and the environment. Organic agriculture is an ecologically-based management system that prioritizes cultural, biological, and mechanical production practices and natural inputs. By strengthening on-farm resources, such as soil fertility, pasture and biodiversity, organic farmers can minimize and even avoid the production challenges that chemical inputs such as synthetic pesticides, fertilizers and antibiotics are marketed as solving.
Source: St. Louis Post-Dispatch