Science in Society Archive

Roundup Ready Sudden Death, Superweeds, Allergens…

Time to Wipe GM Crops Off the Globe

Dr. Mae-Wan Ho and Prof. Joe Cummins update on the failures of the most widely planted GM crops

GM crops have failed on every count

Evidence has existed for years that genetically modified (GM) crops have lower yields, perform poorly in the field, use more pesticides and result in reduced profits for farmers [1] (“GM crops failed on every count”, SiS13/14). Yet the relentless growth of GM crops continued, through a combination of hype, half-truths and outright falsehoods and corruption [2].

According to industry-backed International Service for the Acquisition of Agri-biotch Applications (ISAAA) - which describes itself as “a not-for-profit organization that delivers the benefits of new agricultural biotechnologies to the poor in developing countries” - GM crops covered 81 million hectares worldwide in 2004, an increase of 20 percent over 2003 [3]. Two traits account for nearly all GM crops planted: herbicide-tolerance (almost all glyphosate-tolerant) covering more than 75 percent of the area, and Bt – crops engineered with toxins from the soil bacterium Bacillus thuringiensis to kill insect pests - in the remaining area.

The failures of Bt crops experienced by farmers all over the world have recently been amply confirmed: ineffective against insect pests, harmful to health and biodiversity, yield drag, pest resistance (“Scientists confirm failures of Bt crops”

Problems with GM crops tolerant to glyphosate or Roundup (Monsanto’s formulation of the glyphosate herbicide) first emerged in 1998 - two years after Roundup Ready (RR) soya was introduced to market - and have been building up ever since (see list in Box).

Damning evidence against RR crops and glyphosate herbicide

  • Glyphosate application is linked to sudden crop death (this article)
  • Roundup-resistant “nightmare” superweeds have emerged (this article)
  • Glyphosate is linked to cancers, neuro-defects, spontaneous abortions (reviewed in The Case for a GM-Free Sustainable World, [4], is toxic to human placental cells at concentrations below agricultural use, Roundup at one-tenths of the recommended agricultural dosage [5] (“Glyphosate toxic and Roundup worse”, SiS 26)
  • Roundup is especially lethal to most species of frogs [6]. It caused a 70 percent decline in amphibian biodiversity and 86 percent decline in the total mass of tadpoles  (“Roundup kills frogs”, SiS 26); also lethal to earthworms and beneficial soil bacteria [4].
  • Glyphosate application is further linked to acrylamide release from the polyacrylamide added to commercial herbicide mixtures to reduce spray drift [7] (“Acrylamde in cooked food: the glyphosate connection”). A new report released earlier this year by United Nations Food and Agriculture Organisation (FAO) and World Health Organisation (WHO) stated [8]: “The neurotoxicity of acrylamide in humans is known from high occupational and accidental exposure when acryalmide is used in industrial processes in the production of plastics and materials. Studies in animals have also shown that acrylamide causes reproductive problems and cancer.”  It recommended that, “efforts to reduce acrylamide levels in foodstuffs should continue.” But there was still no mention of glyphosate connection
  • RR soya showed yield drags averaging 6.7 percent compared with non-GM varieties in a study based on 8 200 trials in US universities in 1998; this finding was confirmed in numerous other reports published between 1997 and 2000 [1]
  • Yield drag in soya was associated with problems in root development, nodulation and nitrogen fixation, particularly in drought or infertile conditions, as the bacterial symbiont responsible for nitrogen fixation is sensitive to both Roundup and drought [9]
  • RR soybean perform poorly in heat stress conditions, with up to 40 percent crop losses [10]
  • RR soya’s GM insert was found to have rearranged since characterised by Monsanto, and contained a large fragment of DNA of unknown origin [11, 12]. At least four extra RNA transcripts capable of being translated into new, unknown proteins have now been found (this article)
  • Allergies to soya rose 50 percent between 1998 and 1999 in Britain as a result of GM soya import [13]. Male rats were stunted by GM soya in Monsanto’s study, consistent with an increase of 26.7 percent in a major allergen, alpha-trypsin-inhibitor, which is also a growth inhibitor [14, 15]. Possible new allergens have now been identified in GM soya (this article)

Glyphosate linked to sudden crop death

Fusarium fungus causing sudden death syndrome in soya and wheat was first reported in an article from the New Scientist magazine several years ago describing an unpublished study by Myriam Fernandez and co-workers from Agriculture Canada [16], which has been completed and published recently [17].  Glyphosate application in combination with no till (crop seeds drilled into fields prepared by herbicide treatment alone) had significantly increased Fusarium head blight in spring wheat.  The Fusarium infection not only affected wheat production but also increased the risk of mycotoxins harmful to humans and farm animals.

Sudden crop death following Fusarium infection is also a problem in soya production.  In growth chamber and greenhouse experiments, glyphosate treatment caused significant increases in disease severity and infection of roots [18]. In field experiments with soya, there was increase in Fusarium disease after glyphosate application, but the disease incidence did not differ between glyphosate tolerant and sensitive cultivars [19].

During 1997, a severe epidemic of soybean sudden death syndrome severely affected several RR cultivars. A follow up study found that disease susceptibility depended on the genetic background of the cultivars [20].

Fusarium sudden death is clearly linked to the use of glyphosate. Presently, it is not yet clear whether the effect is due to the residues of plant material in the soil resulting from herbicide use or whether the fungus itself is affected by glyphosate.

Farmers’ nightmare in RR superweeds come true

Field of RR crops have been suffering infestation of weeds resistant to glyphosate and Roundup for several years. Now, the farmers’ worst nightmare has come true. The dreaded palmer pigweed has become Roundup resistant, Monsanto admits [21]. Pigweed is considered one of the very toughest herbicide resistant weeds to deal with, and palmer pigweed especially so, it can get to six feet tall.

Up until now, Monsanto’s Roundup was seen as a particularly effective herbicide for palmer pigweed. This was one of the selling points of Roundup Ready crops. Roundup Ready crops tend to yield less, and it is the ability of Roundup Ready to deal with palmer pigweed that makes it worthwhile.

The palmer pigweed population tolerated “extremely high rates of glyphosate applied in the field under excellent growing conditions,” according to Stanley Culpepper, University of Georgia weed scientist. The resistant population infests 500 acres of Roundup Ready cotton in central Georgia.

Common waterhemp, also known as pigweed, from seed collected from suspect fields in 2004 showed high tolerance to glyphosate in greenhouse experiments [22]. The weeds were found in fields planted with Roundup Ready soybeans continuously since 1996. “Common waterhemp is our No. 1 weed problem in corn and soybeans in most of Missouri.” said Kevin Bradley, Missouri University extension weed specialist, “With the introduction of Roundup Ready soybean varieties, glyphosate (the active ingredient in Roundup and similar herbicides) became the No. 1 herbicide used in soybean fields.”

The problem developed over the past three years at one site and the grower continued to use increasing amounts of glyphosate. The weeds survived a dosage of glyphosate almost 10 times the recommended rate (6lb per acre as opposed to 0.75lb).

Last year, glyphosate-resistant common ragweed was confirmed in Missouri, which was also resistant to 10 times the normal rate of application. Marestail and ryegrass had already developed glyphosate resistance even earlier.

Three years ago, an independent market research study predicted that RR resistance was set to hit the economic value of farmland, wiping around 17 percent off land rentals. More than half of farm managers surveyed placed glyphosate resistance in weeds ahead of weed resistance to other herbicides. Glyphosate-resistant maretail was found in Delaware, Tennessee, Kentucky, Indiana and Ohio. Glyphosate-resistant ryegrass was reported in California. Weed scientists in Iowa and Missouri were then testing waterhemp; and complaints about the marginal control by glyphosate of velvetleaf, ivyleaf, morning glory and lambsquarters had also surfaced. The report, commissioned by Syngenta, had been quietly circulated to farmers and landowners via its PR company, Gibbs & Soell [23, 24].

Monsanto recommends using additional herbicides, not only on Roundup Ready cotton, but also Roundup Ready soybeans and corn [21]. Research in “Palmer amaranth management” continues.

Unknown extra proteins in RR soya?

RR soya was approved for commercial growing in 1996, but independent molecular characterisation was done only in 2001 [12]. The GM insert was found to be scrambled since characterised by Monsanto. The insert contains the epsps gene responsible for glyphosate tolerance, but a further 250bp fragment of the gene is located downstream of the nos terminator from A. tumefaciens. A terminator normally tells the cell where to stop transcribing the message, but the cell appears to have ignored this signal, and at least 150bp of this DNA beyond the nos terminator are transcribed [25]. The read-through transcript is further processed, resulting in four different RNA variants from which the transcribed region of the nos terminator is completed deleted. That means the RNAs could be translated into new and unknown proteins. The nos terminator is used in many GM crops, suggesting that novel proteins may be present in other GM crops as well.

Possible new allergens in GM soya

The possibility that new proteins are present in GM soya is also indicated in another study comparing the allergenic potential of GM and wild type soya in South Korea [26]. GM soya extract showed a banding pattern different from the wildtype, in particular, there is a distinct protein band at 80 000 Da (Dalton, unit of molecular weight) in the GM soya absent from the wildtype.

Skin prick test performed on 49 children who visited the pediatric allergy clinic at Severance Hospital, Yonsei University and Ajou Univeristy in Seoul, Korea, identified 13 children who reacted positively to wildtype soya, and 8 of them also to GM soya; one child reacted only to GM soya. Specific IgE antibodies to soya allergens were found in 9 children. The protein bands in wild and GM soya that reacted with sera from two children were mainly between 20 and 65 kDa, although the pattern differed between GM and wildtype soya. GM soya showed a unique strong protein band that reacted with IgE at ~25 000 Da in one sera while wildtype soybean showed a moderately strong band ~30 000-36 000 Da in both sera.

These findings suggest that new allergens may be present as the result of genetic modification.

Glyphosate accumulates in roots and reproductive tissues

There are several fundamental flaws in RR technology. Glyphosate is rapidly translocated to, and accumulate in roots and reproductive tissues, resulting in reduced pollen production and viability, or increased fruit abortion. Glyphosate affects the relationship between RR crops, plant pathogens, plant pests and symbiotic microorganisms, nitrogen fixation or accumulation [27]. These may account to some extent for the yield drag that has been consistently observed, and increases the exposure of livestock and humans to toxic herbicide residues.

Wipe GM crops off the globe now

We must wipe GM crops off the globe now and shift comprehensively to non-GM sustainable agriculture. This was the call of the Independent Science Panel after a thorough review of the evidence in 2003 [4]. Their case for a GM-free sustainable world has been considerably strengthened since.

Conventional industrial agriculture has been showing signs of collapse from decades of unsustainable practices, including massive reductions in grain yields for four successive years. With water already depleted in the major bread baskets of the world, and oil rapidly depleting, and global warming predicted to further compromise crop yields, there is a real threat of not producing enough food to feed the world [28-30], which is why we cannot afford to waste any more time with GM crops. GM crops are industrial monocultures writ large: more damaging to the environment, more genetically uniform and hence more prone to disease, use more pesticides, according the US Department of Agriculture’s own data [31], and according to farmers’ experience from all over the world, require more water and are less tolerant to drought than non-GM varieties [32]. Persisting with GM crops now will have catastrophic consequences on world food security.

Article first published 03/10/05


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