Thursday, April 26, 2012

Humankind vs Weeds - The Epic Battle

The Center For Food Safety recently touched off a controversy by using a misleading and manipulative term - “Agent Orange Corn” to describe a biotech (GMO) trait working its way through the regulatory process.  The technology will make corn, and later other crops, tolerant to a herbicide named 2,4-D.  In the early 1960s that was one ingredient in a defoliant mix used by the US military in Vietnam; however, a one minute Wikipedia search shows that the terrible health issues with Agent Orange were caused by an unrecognized dioxin contaminant in the other herbicide in the mix.  Since that time, 2,4-D has passed decades of increasingly strict safety reviews.  It still used in 70 countries and is a common ingredient in the products homeowners use to control weeds in their lawns.  Such facts have not prevented elements of the blogosphere, Organic and environmental community from spreading the disinformation.  The credulous reception of this message suggests that there is a need to explain the importance of chemical weed control to the non-farming public.

Weeds are serious business.  Ever since humans began to farm more than 10,000 years ago, they have battled weeds.  It has been a struggle of literally, “Biblical proportions.” In Moses’ narrative of “The Fall” in the Hebrew scriptures (written ~4000 BCE), Adam and Eve are not only removed from the Garden of Eden, they were each given a specific curse which would continue to effect their respective sexes:  Eve got “pain in childbirth.” Adam got weeds.  “Accursed be the soil because of you!  …It will yield you brambles and thistles… By the sweat of your face will you earn your food ...”  (Genesis 3:16-19).  In developed nations like the US, this “curse” falls mainly on the >1% of the labor force that still farms.  The rest of us need to understand their situation.

For millennia there were two ways to grapple with weeds - pull or hoe them with intense human labor, or tolerate their yield-limiting effects.  Then, in the early 18th century the ancient battle with weeds began to change.  An English agronomist named Jethro Tull (not the epic rock band), began promoting “horse-hoe husbandry.” Farmers could use simple, animal-drawn machinery to plant crops in neat rows and then physically destroy the weeds in between (tillage).  Crop yields increased as did the amount of land that one individual could farm.  Tractors accelerated these trends.  However, there was an environmental downside.

Mechanical tillage greatly increased soil erosion and the water pollution associated with it.  In some areas tillage contributed to the “Dust Bowl.”  As soil is tilled and re-tilled, it declines in its ability to store nutrients and to capture and hold rain water. Beyond these issues, tillage did not fully remove ”Adam’s curse.”   Weeds like Canada thistle and Native Bindweed are quite efficiently spread over fields by tillage equipment.  

Though soil degradation continued, the need for tillage was essentially unquestioned until 1943 when Edward Faulkner wrote his radical book, “The Plowman’s Folly,”  questioning the need for tillage in agriculture.  That idea, and the advent of chemical herbicides, led scientists and farmers to explore ways to farm without major soil disruption.  In 1960 farmers began the first commercial-scale attempts to farm without plows or harrows.  The “No-Till” movement began.

The original drivers for attempting “No-till” were soil erosion and fuel costs. It soon became clear that “no-till farming” had many more advantages: reduced water pollution, rainwater conservation, and restoration of soil quality. As no-till advanced, some farmers were not only dealing with the curse of weeds, but also doing so in a way that was far better for the environment than in the old days of “the plow.”  The introduction of herbicide tolerant biotech crops (GMO) in the late 1990s increased the adoption of no-till farming methods.  There is much more room for adoption of no-till and related, sustainable farming advances, but this is clearly the direction we need to go.

Unfortunately, the curse of weeds remained.  It was widely expected that weeds would eventually be selected which were resistant to the herbicides used on biotech crops.  This had happened with many classes of chemicals before biotech.  The slight surprise was how long it took.  Several important weeds have now become resistant to “Roundup®” starting yet another chapter in the ancient battle with weeds.  What farmers can do is to follow “resistance management practices” by switching herbicide “modes of action” and other methods to stay a step ahead of their old enemy.  The 2,4-D resistance trait in the recent controversy is being developed specifically for that purpose.  That, and other new herbicide resistant crops that are in the pipeline, would be welcomed by farmers still battling “Adam’s curse” of weeds, and they will hopefully help even more farmers maintain, or make the challenging transition to no-till farming. 

There is more at stake than progress with no-till.  Since 2007, we have entered a period of volatile global food prices and supply problems that are unprecedented in modern history.  We are trying to feed more people, feed many of them better than in the past, and to do so in a time of climate change that will only make farming riskier.  This is no time for non-farmers to begrudge the farmers any tools which pass muster in our regulatory framework.  The weeds have shown that they will always be there, as will be the need to deploy new technologies in a prudent manner. 


  1. First of all I appreciate your reference to Genesis 3 as I feel it is very instructive in how and why we farm. Weeds are not the curse, they are a result of the curse on the soil. You only mentioned two methods for dealing with weeds, I believe there is another. There are many books that deal with why weeds grow but my favorite is the book by Charles Walters titled " Weeds, Control Without Poisons. In it the reasons of why weeds grow are examined and it has been found it weeds grow in imbalanced soils. Then to make matters worse we inl agriculture add soluble fertilizers that make the imbalance even worse.
    We will never attain Garden of Eden- quality soil but we can certainly do better then we are doing now in commercial agriculture. One of the best ways is growing multi- species cover crops to provide natural nutrients for our future crops which are insoluble but still available and stable in the soil. Not only does this practice help in regaining soil balance but it also helps reduce weed pressure as well. When limited tillage and livestock grazing is also incorporated with this program, soil balance is even more inhanced.
    This approach may not be as easy as just using chemicals but it is far better for our soils and our food.
    Rob Jones

  2. Rob,

    I don't agree with the idea that weeds grow in "unbalanced soils," but I do agree that cover cropping is one useful tool in the management of weeds and can supply some of the nitrogen that is needed. The plant ultimately gets that nitrogen in exactly the same form (nitrate, ammonium ion) as with synthetic fertilizer. The release just isn't sufficient during the period of most rapid crop growth. They can't supply the P, K and other nutrients. Neither can animals

    Many of the most troublesome weeds are invasive species that have been accidentally moved around the world.

  3. Rob,
    Also, long-term no-till farming can eventually exhaust the weed seed bank and make weed management even easier

    1. s.d.,
      I didn't think we would have common ground (no pun întended) about what a balanced soil consists of, but I think if we could take a peek at some Garden of Eden soil, it would be much closer to soil William Albrieght advocated for than what commercial consultants promote. We live in the San Luis Valley and the wind blows most of the year and with all the irrigation ditches, all the weeds in the valley get distributed year-round. And yet not all those seeds grow on all farms because of different soil conditions as well as nutrient deficiencies and excesses, in spite of a full weed seed bank.
      As for your hopes of eventually "exhasting the seed bank" with no till, I don't share you optomism. When having to rely on more hericides, more resistance will occur which will keep the weed seed bank full of deposits. (pun intended, sorry) The focus on killing weeds is misplaced, the curse was on the soil, not the weeds and thus the answer is in the soil.

    2. JO,
      You live in a beautiful place in the San Luis Valley. I grew up in Colorado and I have been there many times. As a kid the sand dunes were one of my favorite spots. Those dunes speak to the rather extreme wind erosion that occurs there, probably long before people started growing potatoes, etc.

      No-till is obviously not a good option for potato growing. I would have to see data to believe that the weed seed pressures from wind blown seed differ greatly by soil management.

      The point of my article was that the species mix of weeds will adapt to any method of weed control that we use. If we use mechanical means, we help the weeds like bindweed or Canada thistle that are propagated by being chopped up. If we use hand weeding, we select for the weeds that have very short generation times we can't keep up with.

      I stick with the idea that the "curse" is mankind's problem and that there is no magic fix with the soil.

  4. Instead of relying on the Bible for inspiration, why not rely on the facts?
    There are two that come to mind as extremely important and you have overlooked them.
    1. The particular 2,4-D resistant strain of corn has not been properly tested on mammalian subjects, and should not be approved for use until such time as those tests have been completed with the assurance of safety.
    2. The availability of a 2,4-D resistant crop seed means two things: firstly, more farmers will be using more of this type of herbicide in the coming years, and secondly, the weeds that farmers are battling will become more resistant to 2,4-D faster.
    I understand the fear principle that is being used by those who decry "Agent Orange Corn", and I don't fully agree with their tactic. But you must understand, science does show that 2,4-D can be toxic to the liver, and can cause many reproductive problems in men who are exposed to it on a regular basis. While 2,4-D can be produced without the harmful dioxins in it, and it has a half-life of only 10 days, why take the risks involved in over exposure? It's a cost versus benefit equation that we should do our very best to ensure we are on the right side of.

  5. Anonymous (and one wonders why)
    1. What would you mean by "properly tested?" There are many testing and data requirements from the USDA, the FDA and the EPA before any GMO crop can be approved. Those have been the same requirements for all the other products over the last 16 years. The 2,4-D has been the subject of hundreds of tests over decades. Your "not tested" concept is just wrong.

    2. "Science" does not show the things you say. Those studies have been rejected by the EPA in many reviews. In some cases their methodology was poor. In others, there were other studies showing the opposite result. You can't cherry pick a few out of scores of studies to make an assessment. If we used that standard we would ban coffee and all sorts of other things. The recent rejection of the NRDC's petition is the latest example. The weight of evidence and a rigorous risk analysis say this chemical is safe enough to be on almost every Americans lawn. Use on some corn fields visited by a farmer in a tractor a few times a season represents almost nothing in terms of human exposure.

  6. I've always hoped to run my yard as organic, just keep on top of the maintenance than spraying these pesticides and stuff. But it's really difficult
    at the moment though where I live, the soil is such poor quality I think
    it would result in way too many problems
    Also visit my web page Garden Treatments Blog


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