Where are the super weeds?

In a recent issue of Nature, Natasha Gilbert took “A hard look at GM crops.” Ms. Gilbert states:

“it can be hard to see where scientific evidence ends and dogma and speculation begin.”


“Researchers, farmers, activists and GM seed companies all stridently promote their views, but the scientific data are often inconclusive or contradictory. Complicated truths have long been obscured by the fierce rhetoric.”

I agree wholeheartedly. Especially when browsing the internet, there is a lot of misinformation, half-truths, and outright lies about GM crops. I’m always glad to see this topic approached with scientific rigor, and I expected an outlet like Nature to do just that. The point of Ms. Gilbert’s article was to separate fact from fiction with respect to some often heard claims about genetically modified (GM) crops. One of the three issues Ms. Gilbert chose to tackle in her article is the claim that “GM crops have bred superweeds,” and she considers this statement “True.”

I was a little disappointed to see the term “superweeds” in any type of scientific publication. I have repeatedly expressed my displeasure with this term, and my graduate students know better than to ever use the word around me. To see it in a publication as reputable as Nature is exceptionally frustrating. But at least this article would be approached with some “scientific evidence” rather than “dogma and speculation”, right? But as I read through the section on superweeds, I saw very little that resembled scientific evidence; rather, lots of opinions, anecdotes, interesting tidbits, some facts and figures, and a fairly compelling narrative. But no “scientific evidence.”

The lack of any scientific evidence in the article probably relates to my biggest problem with the term superweed: nobody seems to know what a superweed is. To determine whether “GM crops have bred superweeds” at least two things are needed:

  1. a definition of the term superweed, and
  2. data that relate use of GM crops to development of superweeds.

Let’s begin by trying to define superweed. Certainly, the term indicates that the weed is super in some way; it must possess some trait that is above and beyond an ordinary weed. Like a superhero that has some ability that the general public does not. So what is this “super” trait that superweeds possess? Can a superweed grow faster than the Incredible Hulk? Or can a superweed spin a web like the Amazing Spiderman? Or maybe a superweed can fly like Superman!

Most of the time, the term superweed is associated in some way with herbicide resistance. So if we define superweed as a weed that has evolved resistance to herbicides, we can then test the hypothesis that “GM crops have bred superweeds.” (ASIDE: The way this statement is phrased, there’s no way it can possibly be true, because crops don’t “breed” weeds. There are some rare cases where crops and weeds cross pollinate, but those have not resulted in any herbicide resistant weeds to date. For the sake of argument, we’ll assume Ms. Gilbert really meant “GM crops have significantly increased the development of superweeds.”) Dr. Ian Heap has developed and maintained a website to document new cases of herbicide resistant weeds, and we can use the data at that site to get an idea of whether this statement is true or false using our definition of superweed.

If GM crops have contributed significantly to the development of herbicide resistant weeds, we would expect the number of unique instances of these superweeds to increase following adoption of GM crops. The figure below illustrates all unique cases of herbicide resistant weeds between 1986 and 2012. I have fit a linear regression to the data from 1986 to 1996 (time period before widespread GM crop adoption) and another regression to the time period 1997 to 2012.


The slope of the linear regression is an estimate of the number of new herbicide resistant weeds documented each year. In the eleven year period before GM crops were widely grown, approximately 13 new cases of herbicide resistance were documented annually. After GM crop adoption began in earnest, the number of new herbicide resistant weeds DECREASED to 11.4 cases per year. The difference in slopes between these two time periods is probably not very meaningful from a practical standpoint. But based on the best data available, we can be quite certain that adoption of GM crops has NOT caused an increase in development of superweeds compared to other uses of herbicides.

Perhaps this definition of superweed is too broad. Let’s define it instead as only “glyphosate-resistant” weeds. The first glyphosate-resistant weed was documented in 1996. This is approximately the same time GM crops were first being introduced into the market. But this first superweed evolved in Australia, where no GM crops were grown. So it is obvious that GM crops are not necessary for glyphosate-resistant superweeds to develop. Certainly, adoption of Roundup Ready crops (the dominant GM herbicide resistance trait) has increased the use of glyphosate in cropland, and therefore increased selection pressure for glyphosate-resistant weed populations. But even so, there are currently more instances of glyphosate-resistant weeds in non-GM crops/sites than in GM crops. The following chart (from www.weedscience.org) illustrates the number of cases of glyphosate-resistant weed species in various crops/sites.


The only 3 GM crops on the chart are soybean, corn, and cotton. All of the other bars represent non-GM systems. If we add up the number of herbicide resistant species in GM crops and compare it to non-GM crops/sites, we should expect GM crops to have a higher number if GM crops are the primary contributor to evolution of superweeds. However:

  • 35 species of glyphosate-resistant weeds are present in GM crops (soybean, corn, cotton).
  • 40 species of glyphosate-resistant weeds are present in non-GM crops/sites (orchards, grapes, roadsides, wheat, fencelines, fruit, barley).

So again, there appears to be no strong difference between GM crops and other sites where glyphosate is used. So this data again suggest that GM crops are not any more problematic than other uses of glyphosate for selection of superweeds.

One deficiency in the above graph is that it doesn’t indicate where the weeds first evolved. Perhaps they evolved in GM crops, but then moved to infest other sites represented in the bar chart above. So instead, let’s take a look at WHERE the glyphosate-resistant weed species FIRST EVOLVED. Of the 24 glyphosate-resistant species documented worldwide, 11 of these superweeds first evolved in GM crops; compared to 13 superweeds that have evolved in non-GM crops/sites. Read those numbers again. And check out the figure below, looking at where and when glyphosate-resistant superweeds first evolved.


Almost any way you look at the data, it appears that GM crops are no greater contributor to the evolution of superweeds than other uses of herbicides. Which makes sense, because GM crops don’t select for herbicide resistant weeds; herbicides do. Herbicide resistant weed development is not a GMO problem, it is a herbicide problem.

It is important to note that the glyphosate-resistant weed species that have had the most economic impact are those that evolved first in GM crops (in particular, the Palmer amaranth noted in Ms. Gilbert’s article). But this is primarily because it is these weed species that were the most economically damaging to begin with (before they acquired their super-powers). But the Palmer amaranth narrative is what leads many people to conclude that glyphosate-resistant weeds are primarily a problem in GM crops. Certainly, Roundup Ready crops have increased the amount of glyphosate used in cropland, and this increased glyphosate use has contributed to the evolution of some new glyphosate-resistant weeds. No one can dispute that. But glyphosate-resistant weeds evolved due to glyphosate use, not directly due to GM crops. And to date, there have been more new cases of glyphosate-resistant superweeds documented in non-GM crops/sites than in GM crops. So it is difficult to make the case that GM crops are any more problematic than other uses of herbicides with respect to superweed development. Unless, of course, you rely on dogma and speculation.

Now, can we PLEASE stop using the term superweed?


  1. Excellent post Andrew, and thanks for saying what needed to be said, and pulling together the data to support it. People don’t realize that most of the weeds that have become resistant to glyphosate were already difficult to control with it in the first place. If you ever see a field where Palmer amaranth has taken over, all you have to do is note the amount of diversity in the species and know how prolific a seed producer it is to realize how it could become resistant. I think one thing the GM opponents have keyed on is the misconception that if glyphosate is one of the best herbicides, and resistance develops to it, those “superweeds” will somehow be resistant to everything else.

    Another thing I cringe at is “GM crops designed to withstand massive amounts of herbicide.” I think this plays off the fact that if you want to market a crop that is resistant to 1x-2x rate of a herbicide, you have to design it to be able to withstand at least 4x-5x just to withstand spraying overlap or errors in herbicide concentration when filling the sprayer tank. Opponents have jumped on this as if the safety factor is the intended rate of application. Yes, they may be designed that way, but that is not the intended use.

  2. I think another misconception on this topic is that people think the weeds have obtained resistance genes from the crops. It’s not usually mentioned explicitly, but I think that underlies a lot of the claims. These cases are just mutations and amplifications and such, right? Not from gene transfer? I wish that was clearer on these discussions.

    1. Good point Mary. All cases of glyphosate resistance (and nearly all other herbicides) to date have arisen from selection of weed biotypes that had a resistance gene(s) already. By applying herbicides, we selected for those types to be the dominant type in the field. It is a simple case of (un)natural selection. There are a few rare cases of herbicide resistance traits moving from crops to weeds, but those were not in GMO crops. Clearfield wheat genes have been passed to the closely related weed jointed goatgrass. But Clearfield wheat was derived through conventional breeding techniques, not through biotechnology. I’m unaware of any GM crop outcrossing with a weed species and transferring the herbicide resistance gene. It is a possibility (say for glufosinate-resistant rice to weedy rice species), but not yet reality.

  3. Something parallel to multi-drug-resistant bacteria. So a superweed might be a weed that has evolved resistance to multiple (2+) different mode of action herbicides

    1. Good idea Arnold. Not something I’d thought of. Let’s define “superweed” as a weed that is resistant to multiple herbicide modes of action. I went back to http://www.weedscience.org to see if there is any data on that. It is a little more difficult (time-consuming) to “extract” from the database, but I was able to at least get the data for the glyphosate-resistant weeds.

      There are currently 24 glyphosate-resistant species, and 169 different individual populations of those species. For example, Italian ryegrass has evolved glyphosate resistance in Chile, Brazil, Argentina, and a couple states in the US. Of those 169 separate populations, 29 are documented to be resistant to other herbicide modes of action as well. In the weed-science biz, we call this “multiple resistance.” But for now, let’s call them “superweeds.” 🙂

      Of those 29 superweed populations, 15 evolved in GM crops (corn, soybean, and cotton), 13 evolved in non-GM crops/sites, and 1 report did not specify where it evolved. So in this case, I suppose one could make the argument that GM crops have been a greater contributor to “superweeds”, but the evidence is still not very strong at all.

      1. Interesting and more than I expected. I don’t think it has anything to do with GMO’s One of my favorite sayings from my plant path prof in grad school is that “nature abhors a vacuum”. If we create a vacuum, either resistance is likely to evolve or secession is likely to occur

      2. Points are well taken Andrew. I have gone through the article you mentioned and agree with the points you raised. Super weed is fancy term (a punch) coined by by some opponent group (not Natasha Gilbert). Problem of weed or resistant weed or are since the inception of herbicides. To my mind, all weeds are superweeds becuase they keep coming despite of enormous efforts made by farmers and currently by scientists. One more thing more. If so called superweed acquired resiatnce, then what?. Dont we other herbicide to kill them. If we have then why people are worried so much about this.


  4. A plant that is resistant to two or more herbicides is described as either cross resistant (if the resistance is against herbicides from the same family due to one resistance mechanism) or multiple resistant (if the resistance is against herbicides from more than one family due to more than one resistance mechanism).

    There is no need for the term superweed – it adds nothing to debate and only serves to sensationalise.

    Herbicide resistance is a result of selection pressure due to the use of herbicides and is independent of the use of GM crops except that GM crops might result in the reduction in cultural weed control and the use of a narrower number of herbicides.

  5. I think it is also important to concider the total number of resistance cases against a particular family of herbicides in light of the total amount of that herbicide that has been applied worldwide.

    The number of glyphosate resistance cases is very low considering the large amount of glyphosate that has been used since it was available. Compare this to the high number of cases of ALS resistance against products that have not been used for as long as glyphosate. Resistance to ACCase inhibitors is also more widespread even though these have been used less than glyphosate.

    From a weed science perspective the very low number of glyphosate resistant weeds is actually the interesting thing here.

    1. I was thinking about this yesterday. I haven’t been around ag long enough to have seen it for myself, but I’ve heard that when glyphosate tolerant crops came out Monsanto was assuring people that weed resistance wouldn’t develop. Obviously that was wishful thinking, but with the surprisingly low numbers of resistant ecotypes given the widespread spraying, maybe they had something there.

      1. I think it was absolutely naive to think that it was impossible for weeds to evolve resistance to glyphosate. But to be fair, I don’t think there were very many people even within Monsanto that truly believed that. But There was some pretty good evidence at the time to support the idea that it was more difficult for a weed population to evolve glyphosate-resistance compared to resistance to other herbicide modes of action. Some research on this was published in Plant Physiology and Weed Technology (Weed Tech paper not open access, unfortunately, and I can’t seem to access Jstor right now. But the abstract can be read here: http://cat.inist.fr/?aModele=afficheN&cpsidt=2750951).

        But most cases of herbicide resistance up until the mid-1990’s resulted from target site point mutations. And, therefore, most scientists (public and private) were assuming that would be the mechanism most likely to produce glyphosate resistant weeds. And to this day, most of the highly resistant biotypes of glyphosate-resistant weeds are not a result of target site point mutations. Most GR weeds are resistant due to non-target site mechanisms, like altered translocation. And most interestingly, Palmer amaranth exhibits resistance to glyphosate due to a mechanism never before observed in weeds: gene amplification. (Anastasia, I think you’ll be particularly interested in this mechanism, being a corn geneticist and all.) Todd Gaines published this work in PNAS.

        So target site resistance is quite rare for glyphosate resistance, and that is what most of the predictions in the 1990’s were based on. But, as always, weeds find a way to survive. All in all, I think glyphosate resistant weed evolution is still “rare” compared to other herbicides. But that doesn’t mean it isn’t problematic (as Lynn points out below). I just don’t think it is any more problematic than other types of herbicide resistance.

  6. Yes from what I hear people saying, the main concern is that RR crops allow/encourage a massive increase in the use of Roundup, so therefore this is assumed must lead to an increase in weed resistance; so it surprising perhaps that the data does not support this. Presumably an increased use of Roundup does not mean necessarily an overall increase in use of herbicides in general, as the RR crop has just displaced a non-GM crop. Good post thanks.

    1. I think the data do support the idea that increased use of glyphosate has increased the number of glyphosate-resistant weeds. But not any more than other uses of glyphosate. And if we recognize that glyphosate-resistant weeds aren’t really any more problematic than weeds resistant to other herbicides, the data suggest that GM crops didn’t worsen the problem of herbicide resistance in general.

  7. Agreed that ‘superweed’ is a horrible misnomer. I recently saw a chemical company that referred to ‘high anxiety weeds,’ but I’m not certain that title applied to herbicide-resistant biotypes, alone. And, yes, we (society in general) have been extraordinarily focused on the glyphosate-resistant (GR) weeds that have developed in GR crops; according to Ian Heap’s site “weeds have evolved resistance to 21 of the 25 known herbicide sites of action and to 148 different herbicides.” So we know that the greater weed resistance problem isn’t limited to the use of GR crops alone.

    That being said, having come from the deep-south, Palmer amaranth cotton world, I don’t think anyone will discount the role that GR cotton/glyphosate use (i.e. the system) had in the rapid selection for resistance in Palmer. At one point in time, it was estimated that 99% of the Georgia cotton crop was planted to one single GR cultivar (which yielded pretty well); that system made weed control in cotton easier and more economical than it had ever been (i.e. reduced need for the use of physical weed control and other herbicide MOAs). Again, I want to convey the notion of ‘speed’ Palmer (probably…I never use definitive terms) would have developed resistance to glyphosate (along a roadside, in an orchard, in a fallow field, wherever…), but I think that the rate of development and spread would have been much slower in a diversified system.

    One thing that I think we need to think about is the weed species themselves. We (collectively) are keen to discuss GMOs and pesticide use, but we often seem to forget that there is a ‘flip side’ to the resistance coin: the biology, ecology and genetics of the weed species themselves. If a weed is, indeed, going to be considered ‘super’ (and I still don’t agree with that description) then we should be talking about it in terms that transcend its herbicide-resistance status (i.e. seed production, life cycle, generations year, reproductive strategy, seed dormancy, etc…). Herbicide resistance, you could argue, is just another weedy trait. However, it is one trait where we can really see how human activity imparts selection pressure. Sure we do it when we select for perennials in reduced-tillage systems, etc…but tillage rarely makes the front page of newspapers and chemicals do.

    1. Agree. And certainly the agronomic practices used in the south at the time were just plain bad. Pick up any crop production textbook in the last 50 years and it will repeatedly stress the importance of crop rotation and diversity of weed management practices. One of the things I always tell my weed science students is that there is no technology that can substitute for good agronomic practices. This includes any type of herbicide or pest resistance trait (GMO or not). Technology should be incorporated into an already agronomically sound system. Continuous, no-till, glyphosate-resistant cotton, with no other herbicides is a certain recipe for failure.

  8. “Certainly, adoption of Roundup Ready crops (the dominant GM herbicide resistance trait) has increased the use of glyphosate in cropland, and therefore increased selection pressure for glyphosate-resistant weed populations.”

    Exactly. This IS the problem. Not knowing this and yet pointing it out is a disservice to people.

  9. Interesting treatment of the subject of resistant weeds.

    Given the increasing use of RR crops and the push to add 24D Ready crops, we will encourage a new double resistant weed (RR24D), so will need to add a third herbicide. Eventually we will see 3-Ready crops and 3-resistant weeds. Then a fourth component will be needed. Evolution in nature and economics both tend to ratchet up the armament and defense in a lock-step system. One wonders where it might end.

    As the GMO corporations get a tighter and tighter grip on the seed markets (at least in the US), the percentage of fields in GM crops will increase. So the divide between non-GMO and GMO crops will become irrelevant insofar as herbicide and herbicide resistant weeds are concerned. Increasingly more powerful or at least broad spectrum herbicides will be needed. The same principle holds for pesticides as well, of course. In both cases there is considerable collateral reduction in local biodiversity and ultimately widespread reduction of biodiversity beyond the actual farming – which itself is anathema to biodiversity, however necessary to support increasing human populations.

    Agricultural land is also being given over from food production to fuel production. Perhaps “superweeds” could be used for fuel as the abundant use of fossil fuels declines.

    While we aren’t there yet, of course, is there any thought being given to creating an eventual exit strategy from the GMO+herbicide+fertilizer concept as the inevitable ratcheting up of resistant crop/weed herbicides becomes ridiculous?

    Thanks for the thoughts!

  10. I finally thought I found an article that would give me some credible info about weed resistance to herbicides triggered by herbicide use in gm crops. But this article seemed tendentious, too, in one part, & so I find I don’t trust it. When it states:
    • “35 species of glyphosate-resistant weeds are present in GM crops (soybean, corn, cotton).
    • 40 species of glyphosate-resistant weeds are present in non-GM crops/sites (orchards, grapes, roadsides, wheat, fencelines, fruit, barley).
    So again, there appears to be no strong difference between GM crops and other sites where glyphosate is used.”

    I think that conclusion is problematic. That’s 35 species per 3 crops, an almost 12 per crop mean vs. 40 species per 7 crops, almost 6 per crop mean. If I’m looking at a crop, I have twice as much chance to find a glyphosate-resistant herb in a gm crop. Perhaps your point is still valid if you somehow compare acreages planted etc., but do you see my problem with the “scientificness” of this?

  11. I gather the professor does not live in Arkansas where we are finding weeds 8 feet tall and 5 inches in diameter that have to be cut with a saw. My friend in Rogers, Arkansas isn’t even near farm land and had to cut one of them down in the nearby ditch. She had never seen such a plant and at first thought it had to be some kind of tree without the typical branches because the stem was so tough. Please stop reading, professor, and get out and walk the land. We have an agricultural disaster looming. I wonder if your university gets an endowment from Monsanto. It is sad to see the lack of common sense that is so pervasive in some intellectuals.

    1. Interesting perspective. The article was only about increasing resistance as a response to herbicides. The observation in the comment suggests a possible transgenic phenomenon associated with the GM crop in which the weed is found, to produce a more accurately named “superweed”. Has anyone investigated the weeds (as opposed to the crops)for gene transfer or for some combined modification as increasing resistance occurs to a create a new phenotypic or genotypic form? Are the huge woody forms in fact unusual or just made more common by the herbicides? Either way the comment bears serious consideration.

    2. Well said Sharilyn. Sellers of GM crops are profiting from the extra weed killer sprayed on GM crops. The introduction of 2-4,D resistant GM crops will profit them more. Monsanto took out a patent on tank mix of weed killer required to kill RR weeds. Don’t forget that in the 1990s the chemical industry bought the seed industry. Monsanto is the biggest owner of seeds worldwide closely followed by Dow, Syngenta, Bayer, Du Pont and BASF. Articles like this are for the rusted on pro-GM lot to pretend this technology is not a massive failure for anyone who is not a chemical company.

  12. I do not think one can give any credence to a single observation on an unnamed species growing in a ditch which has not been verified to be glyphosate resistant but has been assumed to be so. All plant species and plants within species are not equally susceptible to glyphosate and there is opportunity for within species selection to occur. This has occurred under both GMO and non-GMO cropping conditions as Andrew has pointed out in the blog. Among species selection probably also occurs – control the most herbicide susceptible species and the more resistant ones have a competitive advantage.

    1. Sharilyn actually proposed going out of the lab and looking at the giant weeds (not just in the ditch, but on the Arkansas farms). Seems like a better approach than dismissing the observation out of hand. Lots of farmers are reporting outsized pigweed for example. What would be the harm in taking a saw and cutting down a few samples to test for changes from the norm (not just morphology, but genetic changes as well) and at the same time test for glycophosphate resistance rather than just throwing the observation away by saying the commenter didn’t provide proof of glycophosphate resistance – something she is unlikely to be able to do on her own.

      I think Sharilyn has a valid point about the error of making conclusions without doing the investigation in the field – and the remarks by Arnold serve only to reinforce her frustration at the lab bench scientist who seems not to be interested in the real world of her farmer friends.

      No one really disputes that both non-GMO and GMO style herbicide uses can encourage herbicide resistance. Her reference is to what seem like something alien in her ditch and on her friends fields.

        1. Thank you. Much better answer, but could be expanded for the non-expert.

          I think Sharilyn would be interested to know that both pigweed and giant ragweed evolve a resistance to Round Up (glycophosphate) and that the resistance is heritable. Pigweed grows to about 6 feet tall and and giant ragweed can reach 15 feet. Either can stop a combine. Given the herbicide resistance and their large size, farmers must now resort to mechanical removal. Glycophosphate resistant giant ragweed is now spreading widely in the US and is as far north as Ontario.

          The likely reason these huge weed plants seem unusual is that in the recent past, they were easily controlled by Round UP but now that is not possible in many areas, hence the plants get to a large size before the crop is harvested or when they are in “ditches” and are unfamiliar at that kind of size even to people who have been around for quite a while.

          1. Every time you get the name of GLYPHOSATE wrong in this discussion, you make yourself seem even less qualified to comment.

            It has nothing to do with sugar or phosphate.

            1. Thanks for the reply,Stu, but in fact, glyphosate is a marketing jargon term for the commercial formulation that is easier to say than the complete chemical terminology. The active chemical is assumed to be glycophosphate (C3H8NO5P) although there may be other materials, such as carriers in the final Round Up formulation.

            2. Glyphosate is not marketing jargon, it is the approved common name for the chemical N-(phosphonomethyl)glycine. It is not “assumed” to be the active ingredient. It IS the active ingredient. There have been hundreds of studies that confirm this active ingredient and its mechanism of action in plants.

            3. All three names (and many more) refer to the same actual chemical. And yes, you are correct that glyphosate is the approved term for the active ingredient in the various formulations of round-up style herbicides.

            4. Your response prompted me to look up the etymology of the word “glyphosate.” It begins with the original discovery of its herbicidal abilities in 1970 by John E Franz, who was an employee of Monsanto at the time. The name “glyphosate” was coined using a contraction of the chemical name “glycine phosphonate” another name for the same chemical, thus making it easier to pronounce.

  13. “Herbicide resistant weed development is not a GMO problem, it is a herbicide problem.”

    So it’s time to cut out herbicides before we grow some unstoppable (I’m gonna say it) superweeds. “Feed me, Maurice!”

    Meanwhile, well-trained Permaculturists generally don’t have a weed OR herbicide problem, that I’ve observed… maybe science has been going the wrong direction for 100 years?

    1. Really? Where are these mega-productive permaculture farms that are feeding more people than “conventional agriculture”?

      1. Up and coming, my friend. Permaculture is new on the scene. But for a five minute taste of a small farm that indeed is feeding many more people than other local “conventional agriculture” farms, search YouTube for Greening the Desert. Will _blow_you_away_ or your money back 😉 Also watch the Zaytuna Farm tours, which are a bit longer, or anything on Sepp Holzer.

        1. And more important than the fact that Permaculture is very productive per acre, it doesn’t create herbicide resistant weeds. (Keep in mind I’m not discussing conventional organic row farming but true honest-to-God Permaculture.) In other words, it holds the promise that we can continue the practice for tens of thousands of years and even see increases in fertility.

          I think I read somewhere in a side-by-side comparison that Permaculture is more productive per acre, but even if you suppose that conventional is 25 more productive (giving the benefit of the doubt), will conventional remain the leader for 100 more years? Will the food be of the same nutrient value? Will it have destroyed more than it has given?

          Let’s not be short-sighted.

          1. If we don’t measure productivity by yield per acre how is it possible to compare systems. Organic agriculture in any incarnation cannot feed the world simply due to available nutrients. There’s not enough manure in the world to grow food for people let alone grow food for the animals to make the manure. I understand permaculture seeks to address some of this but I am yet to see a profitable permaculture operation that doesn’t rely on income from another source, eg training, tours etc.

            1. “Organic agriculture in any incarnation cannot feed the world simply due to available nutrients. There’s not enough manure in the world to grow food for people let alone grow food for the animals to make the manure.”

              Supposing you’re right, that there aren’t enough nutrients, why wouldn’t a blended approach be workable? Permaculture for pest control and some plant feeding, and big Ag-style fertilizer for the rest of the feeding? This could bridge the gap and cut back on the herbicide resistant weeds since no pesticides are used.

              But I doubt you’re right. From what I’ve seen, fertility gradually increases.

              “I am yet to see a profitable permaculture operation that doesn’t rely on income from another source, eg training, tours etc.”

              I have. Scroll up, I gave directions how you could see it for yourself, too.

              And how many big Ag farms are truly profitable without the massive government subsidies?

              Now if you’ll excuse me, I am trying to heal from chronic fatigue and I do my best to avoid debates on the internet. Sucks too much energy. You may have the last word. God bless!

            2. Fertility can’t increase as long as nutrients are removed in the form of harvest and not returned. Of course there are opportunities for fusion, it just doesn’t seem like anyone is interested in the realities of 7 billion mouths to feed, and would rather stick to elitist notions of “naturalness”

        2. Permaculture has been around about 20 years less than the Green Revolution, which has been credited with feeding over a billion people. When is permaculture going to feed a billion people? It has been around almost 40 years now.

          1. That is a very observant comment, yet it ignores that Permaculture is (its biggest downside) difficult to learn and unfamiliar to farmers; By contrast, the “green revolution” fit right in line with what farmers were already doing, with immediately measurable results, even with questionable long-term results.

            When is it going to feed a billion people? You probably didn’t watch the five minute video to see it with your own eyes, for if you had I doubt you would be asking that question.

            1. I am well aware of Sepp Holzer, but as I said, he supplements his income with tours and workshops, does he make a living purely from farming? I think the idea of everyone being farmers is appealing to some, and a living death for others. I believe in diversity of human endeavour as much as diversity in food production. The idea that Holzer can grow plants withotu fertiliser is hard to understand, unless there is a definition of fertiliser that differs from my understanding of “plant nutrients”

              I have an issue with the idea of Permaculture being “new”, because it’s not new, it’s old enough to have mature examples, and there are few, and the few that exist are reliant on education as a supplement, and are not demonstrably more productive than conventional systems.

              Sure, the green revolution tapped into what farmers already do, it’s a lot easier to change individual practices than behaviours. But until everyone lives in permaculture systems, the design revolution it promised does not feed the population, or even come close.

            2. By the way, I wasn’t being sarcastic when I noted that you made an observant comment. You may have the last word. God bless!

  14. Dear Andrew,

    I really enjoyed this article and today am sharing it on my FB page, which can be found here: http://www.facebook.com/hatepseudoscience

    I wanted to let you know because there are bound to be some angry/uninformed comments, and I thought you might like the chance to defend your piece. No pressure to join the conversation, I just wanted to let you know.

    Thanks for a great read!

  15. Dear Andrew,

    Very interesting article (thanks to the pseudoscience FB page for pointing me to this). I work in this field in Europe and am continually frustrated by the non-adoption of GM crops in the EU when all the evidence points to their safety, but the scaremongering frankenfoods people seem to have the ear of the tabloid newspapers.

    Is there a similar study on the resistant weed biotypes in the EU since 1997? As per your graph of the introduction of GM crops? And does this show the same trend as pre-1997?
    I suspect there are as many cases being recorded within the EU as beforehand. And multi-herbicide resistant blackgrass has emerged in the UK without any GM crops being grown there.


  16. Great post Andrew. I’m an Italian researcher currently working on GMOs and I’m taking advantage of the excellent work you guys are doing 🙂

  17. I am extremely surprised by the conclusion you seem to be deriving from this data. Roundup resistant weeds growing in fields not treated with roundup should be sounding a huge alarm bell that the effects of what we are putting in one field is affecting weeds in another field. This is the most dangerous potential situation for spreading not just the genetics of GMO crops in one field to another but also spreading the resistance in the weeds far and wide. I think your hard work in bringing this together has supplied ammunition for a cause you don’t support. Are you so blind to your predetermined cause that you don’t even ask the simplest scientific question regarding your own work or is it all you care about that we don’t use the term superweed?

    1. Dear Bagheri, You mean if there is any spread of round-up resistant weed, it can not be control by other herbicide too. Simply tell me if a weed is get resistance to X herbicide, what is the to control that weed. In opinion herbicide Y is still available us to control that weed. Now please tell me in what way that round-up resistant weed is ‘super weed’, if we have option to kill that by other herbicides too. Very normal situation as we do in other herbicide resistant weed.

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