The dicamba tsunami

October 2017

Much in the agri-news in June were reports from US farmers whose crops had been damaged by their neighbours' use of dicamba herbicide on the latest GM crops [1].

It seems Monsanto was over-eager to sell its new decamba-tolerant soya technology so that the GM seed hit the fields before the technical details for using it had been sufficiently developed. The result has been widespread injury not only to non-dicamba-tolerant soya, but to fruit and nut crops, specialty crops, and home gardens. Damage has been progressing so fast that as soon as the statistics were compiled they were out of date. As at 15th August 2017, complaints had been made in 21 States, affecting 3.1 million acres of soyabeans alone and inciting 2,242 official investigations.

Because dicamba has a long history of use on grassy crops such as maize and forage, and the 'Roundup Ready' glyphosate tolerant GM crops have been with us for decades, it seems the new dicamba-tolerant soya was expected to slot seamlessly into the agricultural arena.

When reports started coming in last year of off-target damage from dicamba spraying, Monsanto hastily reformulated the weedkiller to make it less volatile and blamed the applicators for on-going problems. The big biotech industry answer was a certificated course to put applicators right, plus a 4,550-word 'label' with instructions on correct use of their product.

Farmers and weed scientists who complained that the label instructions are confusing and make it hard to use the product safely have been told that the label "uses very simple words and terms", is not complex enough to prevent correct application, and that the persistent off-target crop damage is all the fault of the "farmers who did not follow the label instructions".

The complexity of this label has been cited in court as evidence the product may be virtually impossible to use properly, and has led some growers and professional spraying companies to avoid the product altogether.

As an example of just how difficult the dicamba label is to follow, it includes the need to spray at a boom height of 24 inches above the crop. This is fine if your field is flat as a billiard table, but normal fields go up and down, and at that height you're likely to hit something and damage the boom. The specifications for appropriate weather conditions for spraying dicamba are such that you'd have to be a meteorologist to follow them: you mustn't spray unless the wind speed is more than 3 and less that 15 mph, or if the temperature gets above 91O F, or if there's a temperature inversion when cold air near the ground gets trapped along with any pollutants, such as dicamba, under a layer of warmer air. This is fine if your soya crop happens to need sprayed just when the weather happens not to be doing the wrong thing. The last straw for some professional applicators was the requirement to rinse out spraying equipment ... three times.

Is it really the fault of the farmers who can't follow instructions, or applicators who can't be bothered cleaning their equipment, or of the ground for not being flat, or of the weather for being too hot, too windy, not windy enough, or upside-down? Or, is that label simply a Monsanto-inspired distraction from the real, intrinsic problem with dicamba?

The real issue with dicamba is its volatility: it has a tendency to head off into the air as a vapour, and once it's in the air, it can travel a very long way. As the temperature rises, dicamba gets more volatile. When this herbicide was used on maize and forage crops, it was always applied earlier in the year when conditions were cooler. Spraying on soya is hitting the summer season and summer temperatures.

That 4,550-word label is mainly about how to avoid spray-drift. The only way to avoid volatility is not to spray at all.

Did Monsanto know that dicamba's volatility would cause a problem? Judge for yourself.

The Company denied university researcher requests to test its dicamba-formulations for volatility, and samples for research came with contracts explicitly forbidding volatility testing. Data supplied by Monsanto to State regulators to 'help' them judge whether its dicamba-formulations were suitable for their climates and geographies, were supplied only in finished form which couldn't therefore be independently analysed. Extra testing and local data, requested by Arkansas' Plant Board were refused.

Arkansas has been particularly badly affected by off-target effects of the weedkiller, and weed scientists there have done some experiments of their own. Every dicamba formulation they tested demonstrated volatility, some as much as 36 hours or more after application. Movement off-target happened despite the most label-compliant efforts. They found that new dicamba formulations, designed to be less volatile to 'solve' the off-target problem, were indeed less volatile in a laboratory setting. Once in the field, the differences were not as evident. Some additives commonly added to the tank mix made dicamba more volatile: these included glufosinate and ammonium-based products. The problem is exacerbated by the amount of dicamba which ends up in the soil after spraying: it becomes volatile as the soil warms up, and can hitch a ride on dust particles [1]. One of the scientists concluded "this is a product that is broken".

And, what was Monsanto's excuse?

Apparently, the Company 'believed' its new dicamba formulation was less volatile than a previous formulation which researchers found could be used safely. Monsanto, therefore, prevented testing because it was unnecessary. Its Chief Technology Officer said "We firmly believe that our product if applied according to the instructions on the label will not move off target and damage anyone." A representative from BASF, which manufactures the weedkiller, said data was still being gathered but he didn't believe volatility was a major factor. Monsanto explained its position is that "Given the timing of the (imminent) approval ... there simply wasn't the opportunity to do additional testing" because "To get meaningful data takes a long, long time. This product needed to get into the hands of growers."


So, biotech science is a matter of 'belief' because to do any real science takes too long.

The latest GM crops are stacked with genes for tolerance to dicamba and glufosinate, all the better to kill you neighbours' crops if you use both herbicides together.

There's an interesting question no one's asking. Since dicamba "has many well-established harmful effects on mammals including neurotoxicity, mutagenicity, non-Hodgkins lymphoma (a blood cell cancer), and reproductive disruption" [1], what effect might all this long-lived, far-travelled dicamba in the air we are breathing have on us?


[1] DICAMBA AND DUST - October 2017

  • Mary Hightower, Dicamba drift: Arkansas researchers find all formulations volatile; 876 injury reports, Agfax, 10.08.17
  • Bryce Gray, Survey: Reports of dicamba damage continue to spread nationally, St. Louis Post-Dispatch, 17.08.17
  • Stephen Steed, No dicamba in '18, weed expert urges,, 18.08.17
  • Tom Polansek and Karl Plume, U.S. farmers confused by Monsanto weed killer's complex instructions, Reuters, 21.08.17
  • Paul Brown, Temperature inversions are a trap for moisture and pollution, Guardian, 29.02.16
  • Emily Flitter, Scant oversight, corporate secrecy preceded U.S. weed killer crisis, Reuters, 9.08.17
Photo: Creative Commons

No comments:

Post a comment

Thanks for your comment. All comments are moderated before they are published.