These herbicidal formulations have been, and continue to be, the lynch-pin of GM crops, the vast majority of which have been engineered to survive spraying with glyphosate. They have, therefore, been central to the profitability of GM and to the biotech industry's control of agriculture.
A recent pest-protection consultant review of the history and future of this herbicide describes the predicament which this particular GM-based agriculture has got us into.
The context in which glyphosate-tolerant crops emerged was, of course, the Green Revolution, with its move away from farm-based manures, composts, crop-rotations and seed-supplies, to a dependence on high-tech commercial crop-breeding and agri-chemicals. Expensive inputs plus industry focus on the most profitable products led inevitably to a steady decline in crop diversity and rotation, in plant strains and their genetic pool, and, because efficient high-tech agricultural operations need to have scale, in the number of farms and farmers.
Dealing with weeds using chemicals is a complex business: applying selective herbicides which will wipe out bothersome plants without killing the crop is a cumbersome technique for large operations, while the technical expertise and advice needed makes it too expensive for small operations. Glyphosate, which kills just about anything green (including all crop plants) was widely used for many years for between-crop ground clearance. The earliest holy grail of genetic engineers, therefore, was to create crops which were the only plants which could survive the weedkiller.
What happened then was a set of unfortunate assumptions which suited the biotech industry purpose too well to encourage checking them out with actual science.
One such assumption was that, because glyphosate had been used so much in the past without any signs of suspected resistance evolving in the weeds, this wasn't likely to become a problem just because there were some GM plants in the system.
Other key assumptions were that because the creation of glyphosate-resistant plants had proved so difficult to achieve, and because the technology is based on bacterial genes generating bacterial GM enzymes (biologically active proteins), it would be extremely difficult for any weed to evolve a matching level of resistance.
The first glyphosate-tolerant GM crops "were not perfect, but they were good enough", and after the huge expense and time needed for commercialisation, the biotech industry had to make them work. Selling a one-size-fits-all labour-saving cropping system to farmers wasn't difficult, except for its cost which included a technology fee. Biotech giant Monsanto got round this by attaching contracts to the GM seed which prevented (amongst other things) seed saving and scientific study. This was a "risky marketing innovation that growers strongly complained about but still signed". Contracts have been notoriously backed up by ruthless policing, law-suits, and a lot of top-notch PR. Put another way, the Green Revolution had agriculture so firmly gripped in a chemical-dependent and over-complex method of crop husbandry that anything which made the process easier was accepted no matter what the cost.
Predictably, the industry-driven shift to planting a few successful GM herbicide-tolerant crops, mostly dependent on glyphosate, led to a further reduction in crop diversity, crop rotation, and the crop genetic pool. It also reduced the variety of commonly-used herbicides from eleven pre-GM to one, and it effectively reduced the expensive research and development of new herbicides to zero while funds were diverted into new GM seeds.
Where we are now, is that none of the assumptions about the weeds' meagre capacity to evolve have proved valid: so far pest plants have evolved nine mechanisms of glyphosate-resistance and these include some of the most problematic weed species .
Glyphosate was always a comparatively cheap weed-killer, so using more volume when things began to go pear-shaped was an easy option. When glyphosate went off patent in 2000 it became even cheaper while the alternative selective herbicides became relatively dearer and even less attractive. Monsanto's answer for farmers using its failing herbicide/GM crop technology is to increase the concentration of glyphosate and add older, selective herbicides to the mix [2,3]. Because there's residual resistance to the older pesticides in the field, 'superweeds' which can shrug off multiple herbicides, including glyphosate, are thriving.
Whether our food supply, in terms of quantity, is benefitting from the glyphosate/GM game isn't clear because Monsanto's stifling of field/farm-level crop comparisons has won that round. However, comparisons between US and Europe suggest not .
"A recent survey of key companies found that it costs $136 million over 13 years to bring a new biotech crop trait to the market. Waiting 13 years uses much of the patent life and is trice as long as some experts now speculate as the likely life span of the utility of a new herbicide. These issues are forcing some companies to look for safer investments."
The last chance for the current GM focus is that another 'glyphosate' can be invented for which another set of herbicide-tolerant GM crops can be created. "Current estimates are that science must screen 200,000 chemicals to find one new product, one that almost certainly will not have a new mode of action" and to which some weeds will already be resistant. "... the number of chemical companies trying to discover herbicides continues to decline from about 45 in 1970 and soon will be down to less than six if the publicly announced mega-mergers (of biotech giants) are successful".
Note that the word 'safety' in relation to glyphosate has not featured once in the above story, although it has been the focus of so many previous articles. It seems the glyphosate/GM game is so divorced from the end-recipient (you) that your safety can easily be swept under the carpet.
It's also so divorced from the natural order of the ever-evolving living environment that the cost will always become prohibitive.
The combined spectres of damage to human, environmental and financial health will make any GM game we choose to play against Nature unwinnable.
 Six years ago it was evident that WEEDS HAVE TRICKS UP THEIR SLEEVES - GMFS Archive February 2010
 REHASHED HERBICIDES IN THE GM PIPELINE - September 2013
 SUPER-TOXIC REMEDIES FOR SUPERWEEDS - September 2014
 AGRICULTURAL REALITY SHOWS NO YIELD BENEFIT FOR GM - January 2014 (this preliminary check on crop yields has since been confirmed)
- Jerry M Green, 2016, The rise and future of glyphosate and glyphosate-resistant crops, Society of Chemical Industry, Perspective
Photo: Creative Commons