Tuesday, January 31, 2012

Herbicide Resistant Johnsongrass: Coming soon to a farm near you!

Pioneer and K State are jointly releasing a set of new herbicide resistant sorghum varieties, which will incorporate resistance to ALS and FOP herbicides. Ironically, these non-genetically modified varieties invoke one of the classic bogeymen of anti-GM thinkers - herbicide resistant weeds.

In the past, I've heard a couple pro-genetic engineering scientists give herbicide resistant sorghum as an example of a potentially irresponsible creation. This is because another Sorghum species is a notorious noxious weed throughout much of the world: Johnsongrass. Presumably, herbicide resistance alleles in a grain sorghum variety could quickly jump to Johnsongrass, where it would subsequently burn through the rural landscape, making the associated herbicides useless. Johnsongrass is without a doubt one of the most strikingly common weeds in roadside ditches and farm fields here in rural West Virginia and Maryland.* This new potential threat of herbicide resistant Johnsongrass is ironic not only because the resistant grain sorghum varieties were created by non-transgenic methods, but also because these varieties were developed specifically as a control for Johnsongrass!

A Pioneer website states that grain sorghum x Johnsongrass hybrids rarely occur and are almost always sterile. I don't doubt this, but the extreme abundance of this weed easily beats any numbers game - especially with the intense selection of regular herbicide applications. I don't know the agronomy of this system or whether the total cultivation/pesticide strategy does anything special to mitigate the risk of ALS/FOP resistant Johnsongrass emergence, but I'm going to assume it's an absolute sure thing unless someone has data to the contrary.

The non-transgenic status of these plants in no way lessens or ameliorates this risk. The method of genetic change is completely inconsequential. I'm usually a big fan of herbicide resistant crops, but this just sounds like a terrible idea to me all around. Anyone know otherwise?

[Also posted at Biofortified]

h/t: Jesse Bussard @cowgirljesse (who wrote about Jgrass here)

* I know of one house where it has apparently replaced the ornamental grasses in the center of the homeowner's garden.

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