The Corpus Callosum

Roundup-Resistant Weeds

Here at ScienceBlogs, we’ve regularly posted about the thorny issue of
antibiotic overuse, and the subsequent antibiotic resistance.
 This is a good example of evolution in action; it’s also a
good reason why we need to study and understand evolution.  

But antibiotic resistance is not the only such example.  The
same principle applies to herbicides and weeds.

Naturally, a good example comes to us courtesy of ,
the company that everyone
loves to hate
.  (There is even a movie now, The
World According to Monsanto
.  It’s on
Google video, here.)

You see, Monsanto has made a lot of money by engineering crops that are
resistant to their most popular herbicide, ® ().
The idea is that you can plant these crops, then bathe the field with
Roundup.  The herbicide kills the weeds, but the crops are

Any biology sophomore could tell you, that sooner or later, you will
get Roundup-resistant weeds.

Now it has been documented.  Roundup was first used
in 1976
.  In 1996, Monsanto introduced Roundup-ready
.  No Roundup-resistant weeds were detected
before the widespread use of the resistant crops.  Even then,
it took a while.  But now…

johnsongrass in Mid-South

Mar 19, 2008 10:09 AM, By David Bennett
Farm Press Editorial Staff

Johnsongrass, the latest entry to the lengthening
list of glyphosate-resistant weeds — in both Arkansas and
Mississippi — was announced in mid-March. It is the first
glyphosate-resistant warm-season grass found in the United States.

“We’re not trying to push resistance in these
weeds,” says Bob Scott, Arkansas Extension weed specialist.
“But there’s close to 5 million acres of Roundup
Ready crops that get two or three applications of Roundup every season.
Plus, we’re using Roundup as a burndown.

“It’s inevitable that such weeds are produced.
It’s hardly a surprise.”

Johnsongrass found in a Crittenden County soybean/wheat field is the
fifth glyphosate-resistant weed discovered in Arkansas. The others:
horseweed (also known as marestail), common ragweed, giant ragweed and
Palmer amaranth, a pigweed…

() is
notable because is it an invasive
that can be toxic
to livestock

In the long run, it may not matter, since industrial-scale agriculture
may not be around much longer.  The thing is, the genetic
modifications are now in the wild.  There is no way to put the
genie back in the bottle.  It is not possible to fully
anticipate the consequences.  

One could argue that the benefits outweigh the risks.  After
all, the more food we can grow, the more people we can feed.
 It would be nice to eliminate hunger.

But, what if our ability to engage in industrial farming is
time-limited?  that is, what if we can only do it for a few
decades, before the petroleum necessary for this kind of farming
becomes too scare to be used for this purpose?  What is no
alternatives are found, or if they are found but not deployed?

Then, we will have grown a population of humans that is too large for
the planet to support.  Many of them will die.  Sure,
some people will have made a lot of money off the scheme, but does this
really make sense?


  1. #1 RichB
    April 15, 2008

    Some would argue we have already exceeded the population the planet can support. As for the money, Monsanto would argue that it is in business to make money. Being in business for any other reason would escape them. A sad situation, though, that must be solved some other way…

  2. #2 Epicanis
    April 15, 2008

    “the genetic modifications are now in the wild.”

    That’s a misleading way of putting it – “modifications” suggests that it happened “on purpose”, implying that the weeds are glyphosphate resistant because the Evil Genetic Modifications™ have somehow jumped from the soybeans to the Johnsongrass.

    As far as I can tell, this is a natural evolutionary adaptation not related in any way to the engineered crops, and not a spread of the “engineered” genes into wild populations.

    That said, does it make me a bad person that when I read this I thought “Wow! Cool!” for purely scientific reasons?…

  3. #3 Dirkh
    April 16, 2008

    Unfortunately, the “wow” factor is pretty low for Midwestern farmers trapped in whatever cycle of seed-weed profitability Monsanto chooses to impose upon them. As a former biology sophomore, I can tell you that this kind of thing has been going on in one form or another for decades now.

  4. #4 dantel
    May 19, 2008

    That’s a misleading way of putting it – “modifications” suggests that it happened “on purpose”, implying that the weeds are glyphosphate resistant because the Evil Genetic Modifications� have somehow jumped from the soybeans to the Johnsongrass.

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