Series: The Benevolent Side of GMOs
The first section of this post is a short continuation from My Conversation With a Scientist, Part One, in which I conversed via email with plant geneticist Kevin Folta, University of Florida. There was a piece of the conversation that I left out by accident and rather than adding it to the original post as an update, I thought it would be best to put it here as an addendum of sorts. We had been discussing the use of Bt (wiki) and glyphosate (wiki) – active ingredient of Roundup. These are two of the most familiar terms associated with GE crops. The general gist of the discussion was that eating Bt or Roundup Ready crops is as safe as eating any other kind of crop.
(Words in bold are my edits.)
Folta: One other thought… remember that plant cells are not that much different from other eukaryotic cells, animal or fungi. Plants that contain these transgenes do well. If they were harmful, the first affects would be seen in the plants. Even when you look carefully at plant proteins or genes, they are generally unaffected by the Bt or EPSPS*** products.
***EPSPS is the enzyme bound by glyphosate
~~~~~~~~~~~~~~ End of Addendum ~~~~~~~~~~~~~~
5/11 Post Begins Here
When I started my Benevolent Side of GMOs series, I promised that I would address problems with the technology and I believe the remainder of this post begins to do so. I will start with glyphosate resistance and its related problems and issues. If there are facts that are excluded here or other points that need to be made, please comment below. I am a humble blogger more than willing to admit that I’m learning every time I post.
Glyphosate Resistance. Anyone following the anti-GMO movement (which I used to do) has heard that word a lot, followed by an even scarier one: superweeds. My conversation with Folta now turns to this topic. Folta is honest here – and forthcoming with the realities.
S4H: I read constantly of the presence of superweeds that are not dying with Roundup application, and that to counteract that, additional Roundup and more and nastier pesticides are used, leading to an overall escalation in herbicides/pesticides. What say you to that?
Folta: There is truth in your statement about ‘superweeds’ mixed with some hyperbole. The fact is that there always were some glyphosate resistant weeds. Weeds are tough critters. In the case of glyphosate they either detoxify it or move it to a part of the cell where it does not interact with the EPSPS enzyme. These are natural models for glyphosate resistance.
Problem one is that when you kill the other weeds with glyphosate, these move in and you can’t kill them. Farmers are seeing this.
Let’s talk ‘superweeds’. These are the weeds that have gradually evolved resistance to glyphosate, developing the mechanisms of detoxification and compartmentation mentioned above. There are 20-some weed species that previously were glyphosate sensitive that now show some degree of resistance. This is a problem and it is growing. Coupled to Problem 1 above, eventually it will be a huge issue unless new steps are taken.
A ‘superweeed’ isn’t so super. It is resistant to one herbicide.
The next step is ‘pyramiding’ genes. You’ll see susceptibility to multiple herbicides that will be used in combination and that will be durable and effective. The downside is that you have to use two herbicides. The second is 2,4-D or dicamba. Both are much nastier than glyphosate, but both have been used for decades in conventional ag. Their use would be at lower levels and we understand them well– they’ve been studied for eons. Drift was an issue, but even that’s been resolved with new formulations.
The upside is that if the odds of developing resistance to glyphosate or 2,4-D are one in a million, the odds of developing resistance to both are next to non-existent. They should have done this from the start.
The issue of weed resistance is a huge problem. It is not GMO specific and many companies are proposing/testing new solutions. Some are just using glyphosate with new surfactants to it penetrates plant tissues more readily. There are other solutions coming too that use other adjuvants to kill resistant weeds with lower applications of herbicide.
S4H: This is helpful but I find myself recoiling at the mention of 2,4-D and of course, I’ve seen it much maligned in many of the articles I’ve read. It is tied to Agent Orange, yes?
Folta: 2,4-D. Yes, much maligned. 2,4-D is an herbicide that mimics a natural plant hormone called auxin. Auxin causes cell expansion and other processes in the plant. Basically, application of 2,4-D causes a plant to grow itself to death. We use it in tissue culture in small amounts because plants respond well to it and it is more stable than natural auxins like indole acidic acid. The reason we don’t use the natural ones to kill plants is because 2,4-D is slow to be destroyed by the plant. It sticks around and works hard longer, allowing smaller doses.
I’m not thrilled with it only because of two main reasons. The first is that it is more toxic compared to glyphosate (which you can drink a glass of and nothing will happen other than getting acutely sick for a few hours). 2,4-D can have chronic effects from exposure at occupational levels and probably is not the best stuff for the critters that inhabit corn fields etc. Glyphosate, no big deal. Now they have to use both (I think the mix is called Enlist, by Dow). Dow has made the corn with “stacked” traits, gly and 2,4-D resistance.
All that said, it has been used for 60 years in conventional ag. To me, the idea of transgenics is to limit and cut agricultural inputs (like herbicides) so this is moving in the wrong (but necessary) direction. The good news is that there is next to no chance of any resistance developing to the mix.
Agent Orange. Again, a warning bell should go off in your head here. This is exploitation of a grim time in U.S. history when chemicals were used as weapons and people died and still are affected. As I mentioned before, 2,4-D and its cousin 2,4,5-T are potent herbicides. In combination they are super effective. The two were sprayed as “agent orange” to defoliate jungle grown in Vietnam and SE Asia. Many people got huge exposures. Horrible images, horrible illness… and the anti-GM movement uses this imagery to scare people about 2,4-D. It is fear again, and scaring people over educating them is unacceptable to me.
The lynch pin here is that it was not 2,4-D or 2,4,5-T that made people ill, at least not the primary cause. The primary cause was a dioxin (back then no big freak out) that was in the mix from the manufacture of 2,4,5-T. That was the culprit.
So 2,4-D was in Agent Orange, but it was not the component that caused the problem. Once again, the facts are ignored to exploit gruesome imagery. You’ll even hear people say that they are going to “dump agent orange on corn” which simply is not true.
So there you have it, another case with a seed of truth expanded into something untrue. Half way through this I remembered that I wrote a blog on this a few years ago. It’s here, and contains similar info in more detail.
~~~~~~~~~~~~~~~~~~~~~~[End of Q & A]~~~~~~~~~~~~~~~~~~~~~~~
So there it is: an honest, rational discussion of glyphosate resistance and what is being done about it. Again, I invite you to add your comments below if you feel something is missing in this discussion or if you have general input.
Here are a few more links that I believe help to fill out this topic, starting with a very recent NY Times Energy and Environment piece covering recent regulatory setbacks for crops containing 2,4-D and dicamba.
Apparently, the word superweed is not part of the vernacular in ag circles. Read Can We PLEASE Stop Using The Word Superweed?
For a very different perspective on organic farms, I recommend this post: Six Reasons Organic is NOT the most environmentally friendly way to farm.
Coming soon: Bt resistance