Plants with names like wind bentgrass, shortawn foxtail and wild poinsettia sound like they’d make a pretty bouquet, but actually, they represent just a fraction of the ever-increasing array of herbicide-resistant weeds around the world.
Because weeds compete with crop plants for soil nutrients, water and light, weed management has always been a cornerstone of effective farming and good crop yields. According to a U.S. Environmental Protection Agency report, herbicides make up the majority of pesticide sales and applications. Data gathered by the International Survey of Herbicide-Resistant Weeds show that resistant weeds have been gaining ground since the early 1980s, a result of global adoption of farming monoculture and a move away from more traditional methods.
Professor of Agroecology Dr. Miguel A. Altieri of University of California, Berkeley, has suggested that while “present capital- and technology-intensive farming systems have been extremely productive and competitive, they also bring a variety of economic, environmental and social problems.
Superweed proliferation and range have exploded since mid-1990s and the widespread introduction of the glyphosate-based herbicide Roundup, patented by Monsanto, and Roundup Ready, the complementary patented seed lines that are genetically-modified (GM) to be glyphosate-resistant.
When Roundup and Roundup Ready came on the market, many saw them as a less toxic solution to the existing palette of older, more harmful pesticides. Over time, plants in and outside the GM crop fields have adapted to pervasive use of Roundup products by evolving a tolerance to glyphosate.
Growers who have adopted specialized production, monoculture, along with the comparative ease and simplicity of Monsanto and related products see increased yields. They also face the necessity, according to Altieri, of “ever-increasing chemical inputs” to maintain crop yields and combat weeds.
An expanding variety of superweeds persist in the face of increased pesticide application, nullifying the goal of using Roundup in the first place. A 2012 study published in Environmental Sciences Europe found that between 1996 – 2011, the use of GM crops such as Roundup Ready resulted in an extra 527 million pounds in herbicide use.
According to the Union of Concerned Scientists (UCS), superweeds impact more than 60 million acres of farmland. The current response has been to implement a range of older pesticides such as such as 2,4-D and dicamba in combination with glyphosate, and at the same time, to approve and implement a range of GM crops resistant to those combinations.
This kind of chemical and GM escalation would likely have a number of effects on the environment, both in and around crop fields according to the UCS:
– The contamination of non-GM plants by GM crops has already been established. It is therefore likely that the crossover between pesticide-resistant GM crops and glyphosate-resistant superweeds would continue to occur with other pesticides. A study published by a team of researchers from Pennsylvania State University, University of New Hampshire, and Montana State University describes how the use of 2,4-D and dicamba damages non-target plants by 75 – 400 times more than glyphosate.
– 2,4-D and dicamba are associated with increased rates of diseases in humans, including non-Hodgkins lymphoma, according to the UCS.
– These pesticides are toxic to many other fruit and vegetable crops, and are more difficult to use correctly, according to an article in the Michigan State University Journal. They are more likely to harm neighboring crop areas as well as non-agricultural areas through air dispersal.
The alternative is to return to the methods of integrated weed management. What many recommend is a diversified approach based on the science of agroecology. This includes, according to the UCS, “crop rotation, cover crops, judicious tillage, the use of manure and compost instead of synthetic fertilizers, and taking advantage of the weed-suppressing chemicals that some crops produce.”
According to Altieri, policies and research over the past decades have favored the development of monoculture; agroecology promotes methods which protect crops, improve soil quality and water use, maintain biodiversity and prevent contamination of other plants, organisms, and pollinators.
The UCS recommends education and support for farmers wishing to use sustainable weed management methods, as well as increased research on crops and cover crops that can help control weeds.
