Glyphosate causes crop disease

June 2017

In 2003, during a 5-year study of crop disease, the first alarm was raised that wheat appeared to be worse affected by 'fusarium head blight' in fields where glyphosate herbicide had been applied just before planting. Laboratory studies at the time also indicated that fusarium grows faster when glyphosate-based weedkillers are added to the medium they're growing in.

Fusarium head blight is a devastating fungal disease which destroys a fifth of wheat harvests in Europe alone. This fungus produces 'mycotoxins' (poisons) known to cause cancer of the liver and kidney, disorders of the blood and lung, vomiting, and damage to the immune system. Anything which promotes fusarium is a serious business.

Worse was to come. Within a few years, studies of plant disease concluded that glyphosate doesn't just stimulate the growth of the fungus. It was also found to increase other diseases in nearly a third of the food crops tested. In addition, it made the crops susceptible to species of fusarium which aren't normally pathogenic at all.

Why this unexpected link between glyphosate and fungal disease should happen is a mystery. Several mechanisms have been proposed, some or all of which might be relevant, for example: application of the herbicide may simply leave more dead plant matter in the soil for the fungus to grow on; glyphosate's significant potential to throw the soil ecology out of balance (it has adverse effects on some beneficial bacteria and on earthworms) will compromise the health of the soil and of the plants living there; the weedkiller binds to essential metal trace-nutrients in the soil (including potassium magnesium, calcium, manganese, zinc, copper and iron) making them unavailable to plants and causing deficiency diseases such as immune system failure. Whatever the mechanism, one thing has become clear: glyphosate's ability to kill plants is due much more to its ability to stimulate disease than to what is popularly described as its 'key' action, it's ability to interfere temporarily with the formation of essential proteins.

With such an obvious potential for agricultural disaster, scientific studies are essential. However, between the huge increases in glyphosate use on GM herbicide-tolerant crops, plus increasing use of glyphosate as a harvesting aid, on top of the traditional use of glyphosate to clear the soil pre-planting:
"It's hard to find an acre in the US that hasn't had glyphosate applied on it in the last three years" (Huber). 
Studying the herbicide's effects using sound science in the field has been rendered almost impossible.

Widespread crop-failure hasn't gripped us, yet. But, as one US journalist suggested, it may be that all these known negative effects of glyphosate have so far been overwhelmed by the increasing use of fungicides and insecticides keeping the plants alive. This would make it just a matter of time before glyphosate gains the upper hand in the chemical war on pests. And the first crop to succumb might well be wheat.

One Canadian University professor, a globally recognised expert in mycotoxins, maintains that studies and farming experience show fungicides are critical when it comes to controlling fusarium and related toxins in wheat. In 2016, a very wet year with perfect conditions for fungal invasion, wheat crops on thousands of farms in Saskatchewan, Canada, were plagued with fusarium disease. Things were so bad that many farmers there couldn't meet the standards for mycotoxin contamination. The most popular explanation for the failure of those 'critical' fungicides is that the fusarium-promoting effects of the glyphosate used to 'dry down' wheat before harvest have finally overwhelmed the chemicals.

Up until now, the agri-chemical industry has been giving itself a pat on the back, not only for saving farmers' crops, but for delivering safe, healthy food. By making available to wheat farmers a stack of fungicidal chemicals for their crops, consumers have been protected from the deadly fungal toxins which would otherwise be present in their food.

Fungicide manufacturers have also been quick to demonise their arch-enemy, organic food: without any chemical 'protection', organic crops will inevitably be more contaminated with mycotoxins and inevitably be a risk to the consumer. The science, however, doesn't back this up.

A review of the science in 2004 concluded:
"peer-reviewed publications indicate that organic foods are not more hazardous sources of mycotoxins than conventional. On the contrary, organic foods tend to be less contaminated, and may provide protection from the toxins".
By 2012, it had also become clear that, whereas conventional and GM systems encourage disease-causing fusarium species, organic systems actually support non-pathogenic fusarium.

During the perfect conditions for fungal disease of 2016, organic stands should have been the worst-affected. But no, even in the areas where conventional wheat was devastated, on organic wheat-growing farms blight was "not a priority issue" nor "a hot button topic". It seems the organic crops growing in soil chock-full of trace minerals uncompromised by glyphosate and absent glyphosate-damaged ecosystems, could protect themselves from disease very well, despite the rain.


Why are we systematically destroying our environment, promoting plant disease, and risking mass starvation and ill-health just to please the biotech industry?

  • Increased Mycotoxins in Organic Produce? Institute of Science in Society Archive, 23.11.04
  • Andy Coghlan, Weedkiller may boost toxic fungi, New Scientist, 14.08.03
  • Scientists warns of dire consequences with widespread use of glyphosate,, May 2010
  • Organic wheat dodges mycotoxin, GM Watch, 3.04.17
  • Robert Arnason, Organic wheat dodges mycotoxin,The Western Producer, 30.3.17

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