Thursday, November 04, 2010

Got to talking here at work about the increasing spread of glyphosate-resistant weeds in agricultural lands. Any pesticide or antibiotic will, given consistent and unvaried usage in a region, breed resistance, and glyphosates - "Roundup" - has been very, very successful and very popular. The answer, obviously, is to shift over to a similar broad-spectrum herbicide in regions affected by resistant weeds, and definitely in regions in immediate proximity to affected regions.

A few years after Monsanto introduced Roundup Ready GM traits, their rival corporation Beyer CropScience offered a competing set of traits, known as "Liberty Link", which introduced glufosinate resistance into the modified crops. While glyphosate and glufosinate are chemical cousins, they attack different parts of the amino acid array, so that glyphosate and glufosinate resistance are not interchangeable. Luckily, glufosinate is similarly non-persistent in soils, which means that it isn't particularly prone to concentration due to heavy usage. It's also not particularly vicious towards mammals, although it is, like most pesticides, not exactly something you want to eat with your morning raisin bran.

However, glufosinates aren't nearly as pugnacious against weeds as classic glyphosates. Usage guides talk about "weed management" rather than "weed control". This is why Liberty Link has been less than a roaring success as a competitor to Roundup Ready traits. Liberty and its cousins are just less powerful and more specialized in their timing requirements than good ol' Roundup and the generic glyphosates. Roundup's an AK-47; Liberty seems to be more of a hobbyist's target rifle, maybe a long .22.

Pioneer's extensive marketing of their Herculex family of GM traits, which includes a base resistance to glufosinate along with the marquee bio-insecticide which replaces the original YieldGard, means that the glufosinates are a widespread alternative to Roundup resistance if it really gets out of hand. But I really hope that someone somewhere's working on a replacement to both, with more of a "kick" than the underpowered glufosinate. As GMO matures, its practitioners have to realize that while the pace is more sedate than in bacteriology, weed and pest management is still very much a Red Queen's Race.

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