GMOs again: the myth of herbicide tolerant crops

A more serious GMO story after yesterday’s frippery.

One of the many myths about GMOs, and one which Owen Paterson used in his GMO lobbying speech earlier this week, is that GMOs will be friendlier to the environment because they will lead to a reduction in pesticide use. The Daily Mail of all media today ran a story claiming that the Agri-business industry lobbied specifically for this policy shift – if true, it would seem very successfully.

Herbicide Tolerant or HT-crops have already been developed and are widely used in the US. You can see the appeal to farmers – spray herbicides anytime without having to worry about killing the crop plants – spray less often because it’s easier to spray at just the right time to kill the weeds. And there is some evidence that herbicide use has decreased within HT crops, so far.

The only problem with the use of HT crops combined with herbicide use is that it drives resistance in crop weeds if spraying is not done properly. And I’m not talking about former cornfield weeds like Cornflower or Corncockle – these are the successful modern weeds like Blackgrass.

Even in the best of all possible worlds, nature can interfere with our best-laid plans. Here for example is an interesting story coming out of Industry junket CEREALS 13. Last year’s appalling weather restricted farmers ability to spray against weeds of cereals fields – spraying in the rain means the herbicide gets washed off before it can do its job – fluctuating diurnal temperates affect herbicide efficacy. Spraying when it’s cold can mean the weeds haven’t come up properly so again less effective.

Using herbicide or any pesticide is basically a game of evolutionary Russian roulette – spray at the wrong time or under the wrong conditions and you drive evolution of resistant strains. And the laws of probability mean it’s inevitable that eventually spraying at the wrong time or under the wrong conditions (or just not well enough) will happen. We all make mistakes and farmers, after all, are only human.

So when an industry expert states “”This (herbicide) resistance potential means we are going to have to get much better control in stale seed-beds, and really focus on maximising the control we get from non-chemical methods” then you know the weeds are winning.

Back to HT crops. If HT crops are used will farmers reduce their herbicide use? Initially yes. But once resistance in weeds appears and spreads, they will have to increase their herbicide use to keep pace with these resistant weeds. Its an evolutionary arms race – very similar to what’s happening to antibiotic effectiveness and resistance in pathogens.

And if you don’t want to take my word for it – here’s an article in Nature about GM driving new superweed evolution.Palmer Amaranth is a weed of Cotton crops in the Southern US. For years after GM herbicide tolerant cotton was introduced, Palmer amaranth ceased to be a problem, until a resistant strain appeared in one place in Georgia 2004. By 2011 it was found in 76 counties across Georgia.

Secretary of State for Agriculture I mean Environment Owen Paterson can act as the Industry cheerleader and I’m sure he’ll do a very good job of it. Let’s just not kid ourselves that this is about anything other than business.

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About Miles King

UK conservation professional, writing about nature, politics, life. All views are my own and I don't write on behalf of anybody else.
This entry was posted in agriculture, farming, GMOs, herbicide resistant weeds, herbicide tolerant crops, Owen Paterson, rubbish weather and tagged , , , , , , , , . Bookmark the permalink.

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