Organic News
Growing Threat of Superweeds
According to the latest figures from the University of Nebraska’s Cropwatch resource, 12 weed species in the USA are now resistant to Roundup, with a further 10 species worldwide also affected. In Nebraska, glyphosate resistant giant ragweed was confirmed to have developed and begun affecting growers in recent months.
Crops resistant to glyphosate have been grown in the USA since 1996 - most common are industry-leader Monsanto’s Roundup-Ready range of crops, which have been engineered to withstand the top-selling herbicide. However, weeds have also developed resistance through natural selection; the first glyphosate resistant weeds identified were rigid ryegrass in New South Wales, Australia, though the problem is now prevalent in North America, affecting at least 13 US states.
The rise of resistant weeds has led farmers in the USA to use to older, more damaging herbicides and, in some cases, increase applications, rather than decrease the amount of chemicals used - one of the major selling points of GM crops engineered to resist glyphosate.
A cause of concern for GM dependent farmers is the fact that herbicide development has slowed over the past few years. This has led some industry experts to state that traditional breeding methods may yet prove to be more effective and resilient than GM.
Weed resistance to glyphosate has increased fivefold since 2007 and is developing at a rate of one new weed species each year, William Reville of University College Cork told delegates at CropWorld in London recently. "In the USA, species such as common ragweed, horseweed, Johnson grass, water hemp and pigweed are resistant. Some 11millon hectares are affected by this development," he said. While Roundup Ready crops have been grown in the USA since GM soya was introduced in 1996, the resistance has developed by natural selection, he confirmed. While the development of herbicide resistant crops was “a very smart technology” a new approach must now be taken, he said.
He suggested that “an alternative would be to genetically engineer crops that are resistant to two or more herbicides, but the concern is that these are mostly older herbicides, none of which are as safe as glyphosate." Use of the term “safe” in relation to glyphosate is a contradiction since it is linked to the development of certain cancers and birth defects among agricultural workers. Developing GM crops resistant to other herbicides would inevitably lead to the same outcome, with weeds eventually developing resistance.
Gillian Westbrook has been appointed to the new position of
General Manager with IOFGA. Coming from a background in the regulatory area...
