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herbicide resistance

Where the superpowers of superweeds come from

Superman had the yellow sun of earth, spiderman had a radioactive spider-bite, but what about superweeds, where does their super power (surviving application of Round-up/glyphosate) come from?

To understand how superweeds survive, we first have to understand why normal weeds (the Jimmy Olsens and Lois Lanes of the plant world) die. <– last superhero reference of this post I promise. (more…)

About the herbicide application report that’s floating around

I’m sure everyone who follows the genetic engineering debate has heard about the report from The Organic Center which lays a net increase in pesticide usage at the feet of genetically engineered crops. So I finally found a link to the report itself [warning pdf, also 69 pages]. I’m neither a statistician nor an agronomist (despite my awesome ISU hat which has exactly that slogan), so I’m not qualified to confirm or refute the numbers they put forward. Hopefully we’ll see more detailed analysis on that end from someplace like Biofortified or Sustainablog. I now have some analysis of the methodology of the report itself, tracked down by gntis on the biofortified forums. What I can do is given a bit of the broader context about the context of their numbers and what they don’t mean. This post will be in the following format:

  • The 318 million pounds in context
  • Chemicals are different
  • –Different Toxicity
  • –Different Persistance in the Environment
  • Herbicide resistant weeds
  • One trait vs a technology

318 Million Pounds in Context

Example tweet:

Pesticide use has skyrocketed by 318 million lbs (in last 13 years) with use of #GMO seeds!

Let’s put that number in perspective. (more…)

Genetically Engineered Crops: Cotton

Field of Cotton in South Carolina. Photo: hdport, flickr

Field of Cotton in South Carolina. Photo: hdport, flickr

Scientific Name: Gossypium itscomplicated*

Genetically Engineered Traits: Insect Resistance (bt), Herbicide Resistance

Details of Genetic Engineering:

Cotton has been genetically engineered to resist both glyphosate (by Monsanto) and glufinsate (by Bayer CropScience) under the names Roundup Ready and LibertyLink respectively. As I’ve discussed in previous posts, there are both economic and scientific advantages to having more than one herbicide/herbicide resistance system as it tends to keep prices down, and slows the development of resistant weeds when any resistance they evolve to one herbicide will be useless if the farmer switches to the other for the next growing season.

But the big deal when it comes to genetically engineered cotton is bt cotton that substantially reduces insect damage (and insecticide applications). In the US both Monsanto and Dow AgroSciences sell their own versions of bt cotton using different bt proteins with different specificities. The Chinese government has also developed and deployed their own bt cotton varieties. Bt cotton is the most widely grown** type of genetically engineered plant in the world today, grown in countries like China, India***, and Australia, where other genetically modified crops are not yet approved, for the obvious reason that it’s harder to get people upset about wearing “unnatural” things than eating them.****

Cotton plant in Turkmenistan. Photo: flydime, flickr

Cotton plant in Turkmenistan. Photo: flydime, flickr

About Cotton: (more…)

Genetically Engineered Crops: Sugar Beet

Two sugar beets. From the USDA via wikipedia. (USDA you are awesome)

Two sugar beets. From the USDA via wikipedia. (USDA you continue to be awesome)

Scientific Name: Beta vulgaris*

Genetically Engineered Trait: Herbicide resistance.

Details of Genetic Engineering:

Sugar beets tolerant of the herbicide glyphosate (created by Monsanto) were de-regulated by the USDA in 2005**.  The beets were first grown commercially in 2008. Before the first seeds were even in the ground, the USDA was being sued in California for approving their cultivation. This fall (2009), a federal judge named Jeffery White ruled that the study of the environmental impacts of glyphosate tolerant beets (part of the data the USDA considered in its decision to deregulate the beets) should have considered the economic impacts of the herbicide tolerant beets on organic farmers. Since the ruling came at the end of the growing season,*** there was no time to breed new conventional seed to plant next spring. There may be enough seed next year, but if so it’ll be a stretch.

I’m keeping sugar beets on the list of genetically engineered crops, because there’s a still chance the plants will be grown next year. The judge still hasn’t decided if his own ruling should result in a ban on growing the beets. That’s all the detail I have room for here, but if you’re interested in the court case and the science behind it, I’d recommend checking out Anastasia’s excellent in depth follow up to the judge’s ruling.

About Sugar Beets: (more…)

Genetically Engineered Crops: Soybean

Soybean field. Photo: Big Grey Mare, Flickr (click photo to view photostream)

Soybean field. Photo: Big Grey Mare, Flickr (click photo to view photostream)

Scientific Name: Glycine max

Genetically Engineered Traits: Herbicide Resistance

Details of Genetic Engineering:

The genetic engineering of soybeans is pretty similar to that of Canola. Roundup Ready soybeans (produced by Monsanto) have been on the market for some time. The soybeans, which allowed farmers to spray an herbicide that kills all the plants in the field besides the soybeans themselves, have been a huge hit with market shares >90%. The benefit here is that being able to use herbicide resistant soybeans has been linked to increased use of no-till farming.* Bayer CropScience recently received regulatory approval for LibertyLink soybeans, their own herbicide + resistance system. Having another system is good for two reasons:

  1. Competition brings down prices for farmers
  2. Being able to rotate between two different herbicides prolongs the usefulness of both. Even if weeds develop some resistance to glyphosate (the active ingredient Roundup Ready crops are resistant to) the weeds are killed next year when the farmer sprays Glufosinate (the active ingredient that Liberty Link crops are resistant to).

About Soybeans: (more…)

Genetically Engineered Crops: Canola

Field of Canola in Bloom. Photo: Joe Shlabotnik, flickr (click photo to view Joe's photostream)

Field of Canola in Bloom. Photo: Joe Shlabotnik, flickr (click photo to view Joe's photostream)

Scientific name: Brassica napus

Genetically Engineered Traits: Herbicide Resistance.

Details of Genetic Engineering:

Two companies have produced canola that is resistant to different herbicides.
Monsanto sells canola (Roundup Ready canola) that is resistant to glyphosate, an herbicide monsanto sells under the brand name Roundup and lots of other companies sell under lots of other brand names since the herbicide itself recently came off patent (the resistance trait is still under patent.)
Bayer sells canola (Liberty Link canola) that resists the completely different, if similar sounding herbicide, glufosinate. Glufosinate is sold under a number of brand names (including, you guessed it, Liberty), but I wasn’t able to figure out whether or not it is still under patent.
About Canola:
Derived from the name “Canadian Oil” canola is an oilseed plant also known as rapeseed. The name change came in the 1970s when conventional breeding (this was approx. two decades before the first genetically engineered plants hit the market) created plants with healthier oil and without the bitter taste , and presumably someone to majored in advertising suggested that selling “Rape Oil” would be a good way to go bankrupt.

Two companies have produced canola that is resistant to different herbicides.

Monsanto sells canola (Roundup Ready canola) that is resistant to glyphosate, an herbicide Monsanto sells under the brand name Roundup and lots of other companies sell under lots of other brand names since the herbicide itself recently came off patent (the resistance trait is still under patent.)

Bayer sells canola (Liberty Link canola) that resists the completely different, if similar sounding herbicide, glufosinate. Glufosinate is sold under a number of brand names (including, you guessed it, Liberty), but I wasn’t able to figure out whether or not it is still under patent.

About Canola:

Derived from the name “Canadian Oil” canola is breed of the oilseed crop rapeseed. The name change came in the 1970s when conventional breeding (this was approx. two decades before the first genetically engineered plants hit the market) created plants with healthier oil and without the bitter taste people associated with rapeseed oil, and presumably someone to majored in advertising suggested that selling “Rape Oil” would be a good way to go bankrupt.

Close up of Canola Flowers. Photo: Pollobarca2, flickr (click photo to see pollobarca2's photostream)

Close up of Canola Flowers. Photo: Pollobarca2, flickr (click photo to see pollobarca2's photostream)

Rapeseed (the USDA doesn’t break out separate statistics for Canola) was the third biggest source of vegetable oils around the world in 2008-2009 at 20.5 million metric tons, coming in behind only soybeans and oil palms.

Canola is the main oil I use in my own cooking. Canola is apparently one of the healthier sources of vegetable oils, but the two things I most appreciate about it are the high smoke point (it’s harder to burn the oil itself*), and low cost. Last time I checked I was able to find a 48 oz bottle of canola oil for 2.99 which was better than local prices for peanut or corn oil. (Olive oil of course comes in much smaller containers that cost $10 or more, not at all suitable for graduate students.)

*Good for someone who is both as indifferent a cook, and as easily distracted as I am.

Herbicide Resistance

Plant breeders can find natural resistance to pathogens. Some crops can be grown in regions where they have few or no natural insects attackers. But every crop with face the problem of weeds, other plants that threaten to steal light and nutrients. And the crops that sustain us will always suffer from an unfair handicap, as crop plants devote much of their energy to food production (whether that means fruits, roots, seeds, or even leaves) while weeds can devote all their energy to outcompeting their neighbors.
Since farmers as individuals and we as a species depend on growing fields of crops like like corn, eggplant or rhubarb and not weeds like kudzu, thistles or chickweed we need to protect our crops. A farmer can protect his crop physically, either sending people out with hoes to slay every plant but his own crops* or using a cultivator to turn over the soil between the rows, hopefully burying or slicing and dicing the majority of the weeds. The first costs money and is miserable for whoever does the work. The second burns extra fuel, bad from both global warming and cost perspectives, and increases soil erosion (top soil broken up by the plows of the cultivator can more easily be carried away by rainfall).
The alternative is for the farmer to defend his crop with herbicides (plant killing chemicals). The problem with this approach is to find chemicals that kill weeds but not the crop plants. Similar to the challenge of finding antibiotics which can kill the bacteria attacking a human body without killing the human her or himself, herbicide developers face the added difficulty that most weeds are much more closely related to the crops they’re competing with than bacteria and humans(which last shared a common ancestor more than a billion years ago). In many cases it is more comparable to finding a toxin that would kill mice, but not humans, at similar dose to body-weight ratios. And even when they find a suitable herbicide, it may have nasty effects on humans (and many herbicides do).
Herbicide resistant lines are can survive broad spectrum herbicides, herbicides that kill all plants, like glyphosate (Round-up when you the brand name version from Monsanto), glufosinate (Liberty) and Imidazolinone (Beyond). Without having to worry about finding chemicals naturally survivable by crop species, herbicides can be used that are far more effective at killing weeds, in addition to being less toxic to humans.** With more effective pesticides, farmers can stop using cultivation as an additional method of weed control, letting the soil remain unbroken, which reduces the loss of topsoil from erosion. The mistake I think a lot of people make is assuming all herbicides are equally bad. Given the choice I’d much rather get lost and wander into a field treated with glyphosate than a field treated with a quarter as much atrazine.
*The worst sunburn I ever got in my life came from a day spend hoeing a cornfield
**The MSDS for the active ingredient in round-up, glyphosate. Basically you shouldn’t rub it in your eyes or take a bath in it, but even then, the result would probably be irritation, not death. Extropolating from the LD50 in rats***(with apologies for nested footnotes), always a dangerous thing to do, a person of my weight would have to eat 500 grams of pure glyphosate to have an even chance of death. And that’s on top of it being classified as Group E (evidence that the chemical does NOT cause cancer)
***LD50 is a fancy way of saying how much of a toxin must be feed to a group of lab animals to kill half of them.

What herbicide resistance is, and why the trait is so valuable to farmers.

Spear Thisle

One of many enemies faced by crops, the spear thistle. Photo John Tann, Flickr

Plant breeders can find natural resistance to pathogens. Some crops can be grown in regions where they have few or no natural insects attackers. But every crop with face the problem of weeds, other plants that threaten to steal light and nutrients. And the crops that sustain us will always suffer from an unfair handicap, as crop plants devote much of their energy to food production (whether that means fruits, roots, seeds, or even leaves) while weeds can devote all their energy to outcompeting their neighbors.

(more…)