Scientific American, May 2011

AGRICULTURE
The Growing Menace from SUPERWEEDS
Pigweed, ragweed and other monsters have begun to outsmart
the advanced technologies that protect the biggest U.S. cash crops

by Jerry Miller


IN THE SECOND WEEK OF NOVEMBER, CENTRAL INDIANA IS A PATCHWORK OF TAWNY
AND BLACK: here a field covered with a stubble of dried corn and soybean
plants; a little farther on, bare earth where the farmer has plowed
under the residue of last summer's crop. This is soil that wants to grow
things, and already if you look closely you can see some shoots of fall
weeds: chickweed, cressleaf and purple nettle. In a greenhouse on the
campus of Purdue University, Chad Brabham, a soft-spoken grad student in
weed science, selects two pots, each holding one 18-inch-high plant,
bearing serrated, three-lobed leaves on a coarse stem. If the plants
look familiar, you might have seen them growing in a vacant lot or by a
roadside almost anywhere in the lower 48 states. They are Ambrosia
trifida, or giant ragweed‹a plant as ugly as its name and as useless,
well, as its cousin, common ragweed, A. artemisiifolia, a machine for
sucking up water and spewing out highly allergenic pollen. If the
farmers stopped farming, it would not take more than a few years before
this part of Indiana would live up to the nickname that agronomists joke
should appear on its license plates: Giant Ragweed National Forest.

Over the past half a century or so, that fate has been kept at bay
primarily by chemical herbicides. One of the most widely used is
glyphosate, best known as the active ingredient in Monsanto's Roundup
weed killers, among others. Brabham positions the two pots in a spray
chamber and fills a small tank with a solution of the potassium salt of
glyphosate. A traveling spray head swiftly traverses the length of the
chamber and soaks the drab-green leaves with what by all rights should
be a lethal dose. Brabham removes the pots and returns them to the
growing table. What happens to these weeds in the next 24 hours will
show, in microcosm, what farmers will face across the Midwest this
growing season.

Glyphosate has taken center stage in an emerging drama in which the weed
killer is the protagonist. "I wouldn't use the word 'catastrophe,' but
there are people saying it could be the worst thing for cotton growers
since the boll weevil." So says Doug Gurian-Sherman, a plant pathologist
and senior scientist at the Union of Concerned Scientists, discussing
the spread of glyphosate-resistant weeds‹aka "superweeds"‹which in the
past decade have expanded their range in the U.S. from a few scattered
occurrences to as much as 11 million acres. This coverage is still a
small fraction of the 400 million acres of U.S. cropland, but it
represents a fivefold increase just since 2007. "That's a huge jump in
the extent of those plants, and I don't think anyone was expecting
that," says David Mortensen, a weed ecologist at Pennsylvania State
University. And as he testified at a congressional hearing last
summer‹called by Representative Dennis J. Kucinich of Ohio to
investigate the U.S. Department of Agriculture's regulation of
genetically engineered seeds‹"there is reason to believe this trend will
continue." If superweeds do rise to the level of a catastrophe, it will
be one that could not only have been predicted but that was also even
fore-seen. Like the antibiotic-resistant bacteria that have infectious
disease specialists fearing the worst, it is a problem we have brought
on ourselves, a reminder of the futility of attempting to outrun
evolution. And more weeds are what we least need in a world that may be
bumping up against the limits of technology to expand food production.

THE MAKING OF KILLER RAGWEED

THOSE WHO MOSTLY VIEW CORNFIELDS from an airplane window probably do not
appreciate how much of farming consists of keeping weeds away from
crops. The very word "cultivate" means not only to make something grow
but also to plow or till the soil, which was the original method of weed
control-up-rooting unwanted plants and burying their seeds. Weeds lack
the stealth and single-minded lethality of insects and microbes, which
can strike seemingly out of nowhere and wipe out a crop in a matter of
days. They grow in plain sight and attack their neighbors indirectly,
robbing those plants of nutrients, water and, crucially, sunlight. But
bugs and disease are typically sporadic, hit-or-miss events, whereas
weeds are ubiquitous. Unchecked, a single giant ragweed plant can reduce
the yield in an area holding 30 soybean plants by as much as half.

Which is why agronomists have been keeping a close eye on the weed
species‹10 at last count in the U.S. and about an equal number in the
rest of the world‹in which certain populations have evolved the ability
to withstand an ordinarily lethal dose of glyphosate. As Monsanto
spokespeople are quick to point out, that leaves more than 300 species
still vulnerable to Roundup. But the 10 include some of the most
prolific and intractable pests infesting cotton, corn and soybean
fields: giant and cornmon ragweed, horseweed, Johnsongrass, waterhemp
and Palmer amaranth. The last, also known as pigweed, is the Paul Bunyan
of weeds, able to grow a stalk as thick as a baseball bat and tough
enough to disable a combine that has the misfortune to

76 Scientific American, May 2011

encounter it. In its herbicide-resistant form, "it's about the closest
thing out there to a weed we can't control," says Thomas T. Bauman, a
weed scientist at Purdue. "It makes giant ragweed [which itself can
exceed 10 feet] look small, and it germinates all season, so after you
think you've killed it off, it comes up again the next time it rains."
Some cotton growers have had to abandon their fields where pigweed has
taken hold. Others have turned back the clock on agriculture by a
century and are sending crews into their fields to whack at it with
hoes. "I've seen more hoe crews in the fields [in 20101 than the past 15
years combined," says David R. Shaw, vice president for research and
development at Mississippi State University. "It's incredibly hard
work," he adds, "and extremely difficult to make a profit."

It is also work that farmers in the developed world thought they had
left behind, with the coming on the scene of organic herbicides after
World War II. Among the earliest was 2,4-1), the first of a large class
of herbicides that mimic the hormone auxin and send the plant into a
lethal frenzy of uncoordinated growth. Other classes of herbicides
attack other processes, such as photosynthesis or nutrient transport.
Glyphosate inhibits an enzyme called EPSPS
(5-enolpyruvylshikimate-3-phosphate synthase) that builds three
essential amino acids in plants and bacteria but, crucial to its
widespread adoption, not in animals. The chemical attacks cells in the
meristem, the growth bud at the tip of the plant. Within a day of
application the plant stops growing, and death typically follows within
a week or two.

Unlike the auxin mimics, which selectively kill broadleaf plants but are
relatively harmless to grasses, glyphosate attacks anything green. And
unlike herbicides that can lie spread on the soil before weeds emerge in
the spring, it must be applied directly to the leaves of whatever you
are trying to kill. These traits limited glyphosate's usefullness for
several decades after its discovery in 1970. Farmers generally could use
it only in the early spring, between the appearance of the first weeds
and the sprouting of the crop, or during the growing season by the
labor-intensive method of squirting it between the crop plants directly
onto individual weeds. Micheal Owen, an agronomist at Iowa State
University, describes weed management in those

May 2011, ScientificAmerican.com 77

years as both art and science, a continuous juggling of herbicide
application, crop rotation, and fall and spring tillage to various
depths, each with a price in money and time to be weighed against the
potential yield loss averted. Each technique also tended to control a
different suite of weeds or, to put it another way, selected for the
ones it did not kill. Those able to survive the onslaught flourished
under 'the attack regimen. Weed problems are cumulative, as seeds mount
up year after year, so the way to stay ahead was to use different
techniques and change them often. Weeds thrive on predictability.

READYING A REVOLUTION

ALL THAT CHANGED in the early 1990s, when Monsanto perfected the
technology to breed crops that could resist glyphosate. Whatever else
one could say about this innovation, it was a scientific triumph that
took, by Monsanto's estimates, 700,000 person-hours of research time. A
seven-year search for the right gene ended in an outflow pipe from a
Monsanto facility in Louisiana. There researchers looking for organisms
that could survive amid the glyphosate runoff discovered a bacterium
that had mutated to produce a slightly altered form of the EPSPS enzyme.
The altered enzyme made the same three amino acids but was
unaffected by glyphosate. Scientists isolated the gene that coded for it
and, along with various housekeeping genes (for control and insertion of
the gene for the enzyme) collected from three other organisms, implanted
it in soybean cells with a gene gun.

This is a brute-force technology in which the selected DNA is wrapped
around microscopic specks of gold that are blasted at soybean embryos,
in hopes that at least a few will find their way to the right places on
a chromosome. Tens of thousands of trials resulted in a handful of
plants that could withstand glyphosate and pass the trait down to their
descendants. Starting in 1996, Monsanto began selling these soybean
seeds as Round-up Ready. Seeds for glyphosate-resistant cotton, canola
and corn followed soon after.

It also was a commercial triumph. Roundup Ready seeds revolutionized the
farming of commodity crops in the U.S. and around the world,
particularly in Argentina and Brazil. Encouraged by Monsanto's
advertising, farmers basically outsourced their weed problems, planting
Roundup Ready seeds and dousing their fields with glyphosate at the
first (and second and third) appearance of weeds. Last year in the U.S.,
93 percent of soybean acres, and a large majority of corn and cotton,
were planted with Roundup Ready seeds. Estimates of global demand in
2010 ranged up to almost one million tons.

Whether this technology has actually helped farmers produce more food is
in dispute. The biotech industry likes to claim that it has, but a study
by the Union of Concerned Scientists in

78 Scientific American, May 2011



2009 concluded that any gains were small and far outstripped by the
progress wrought by conventional breeding, at a small fraction of the
cost. But the Roundup Ready system had other advantages as well. Most
experts agree that among synthetic organic pesticides, glyphosate is one
of the least toxic and persistent. And its effectiveness when used on
Roundup Ready crops meant farmers had less need for tillage. No-till or
low-till farming, a trend that began in the 1980s, saves fuel and
reduces erosion and nutrient runoff into waterways. Glyphosate "is an
incredibly effective chemical for killing plants," says John Lydon,
chief weed scientist at the USDA, "and one of the most benign
agricultural chemicals in use."

That state of affairs was, of course, too good to last. "Weeds are
constantly evolving by adapting to high selection pressures imposed by
crop production practices," says Purdue horticulturist Stephen Weller.
Glyphosate resistance was almost unknown in the years before Roundup,
but since then it has appeared in new species of weeds at the rate of
about one a year. Applying the same herbicide to the same crop every
year, with no other weed-control measures, creates a perfect laboratory
for the evolution of resistance, Bauman says. "The resistant weed is out
there. Just apply the herbicide, and you'll find it."

The first question everyone has about these glyphosate-resistant
superweeds is whether they have the same resistance mechanism found in
Roundup Ready seeds‹that is, did the gene jump the species barrier into
weeds from crops? Owen, expressing the consensus of plant, biologists,
says no; weeds native to the U.S. are too far apart from soybeans, corn
or cotton to interbreed. (In contrast, certain plants are considered too
close to their weedy relatives to run the risk of adding herbicide-
resistant genes, such as creeping bentgrass, the turf of choice for golf
greens.) Under the evolutionary pressure of glyphosate, weeds developed
their own defenses. Resistant pigweed has the normal form of the EPSPS
gene, not the altered allele engineered by Monsanto. But it has the
normal gene in vastly greater numbers, from five to 160 times as many
copies, which produce the enzyme in amounts that overwhelm the
inhibiting effect of the herbicide.

MYSTERY SURVIVOR

BACK IN THE PURDUE GREENHOUSES, Brabham's experiment with giant ragweed
demonstrates yet another kind of resistance, which appears to have also
evolved independently. In susceptible weeds, the effects of glyphosate
show up first in the rapidly dividing cells of the meristem. (The
chemical also travels to the roots, where it may interfere with
resistance to fungi; plants are notoriously hard to autopsy, but
shriveled and rotted roots are often noted after spraying with
glyphosate.) But when Brabham examines his specimens 18 hours after
spraying, he sees something very different: the big leaves have begun to
curl and brown, but the meristem is green and healthy. The plant appears
to be segregating the herbicide in the leaves, which over the next week
or two will die and fall off. But the plant will survive and regenerate
from the meristem. "I'd love to know what's causing that," Weller says,
"because you sec the same thing in pathogen resistance. The leaf dies,
but it doesn't spread to the rest of the plant. That's something we
could really make use of, if we knew how it does it."

It is important to remember, Weller says, that Monsanto's Roundup Ready
technology did not cause this problem by itself; the weeds evolved
resistance to glyphosate on their own. But the availability of seeds for
glyphosate-resistant crops enabled farmers to take the path of least
resistance, which was to douse their fields with Roundup to the
exclusion of other weed-control techniques and chemicals. They could
have taken a lesson from medicine, which relies on a multiple-drug
strategy to control fast-mutating viruses such as HIV; the odds are very
much against a single organism spontaneously evolving resistance to
several different chemicals at once, so ideally there are no survivors.
It is fair to say that Monsanto, with a huge investment to recoup, did
not exactly discourage them. "[Glyphosate resistance] could have been
avoided, or at least put off for a long time, if farmers had used
another herbicide in combination," muses Glenn Nice, a Purdue extension
agent who deals with farmers around the state regularly. "But farming is
a business like any other." Actually, not exactly like any other:
farmers make their money at the margins‹that is, after defraying
expenses‹and their efforts are constrained not just by cost but by the
length of a day and a growing season. "An ounce of prevention is worth a
pound of cure," Nice adds, "but you still have to pay for the ounce."

And farmers will be paying. Biotech and chemical companies are hard at
work inserting genes for resistance to other herbicides into crops.
Monsanto hopes to market, within the next year or two, seeds for plants
resistant to an herbicide called dicamba, and Dow has developed a gene
for resistance to 2,4-D. The traits will be "stacked" along with Roundup
Ready genes onto a new generation of genetically engineered seeds, so
that farmers can broadcast two herbicides on their fields, together or
sequentially, rather than relying just on glyphosate. DuPont already
sells seeds with resistance to glyphosate and another herbicide,
glufosinate. That is in addition to other engineered traits bred into
commercial seeds, such as the gene for Bt, a naturally occurring
insecticide.

This is a prospect many agronomists greet warily. Dicamba and 2,4-D are
older chemicals whose use has been grandfathered in under federal
regulations; both are considered more toxic and persistent than
glyphosate and might not easily get through the registration process if
they were introduced today. Dicamba, in particular, has a tendency to
volatilize after application, drift and settle on neighboring fields,
where it has been known to damage other crops or wild vegetation. And
there is the question, still unanswered, of how many added traits you
can load onto a seed before you begin to impair the plant's vigor and
productivity. Every additional thing you ask of an organism takes energy
away from what it is supposed to be doing in the first place‹in this
case, growing food.

The bigger question has to do with the future of agriculture and how
farmers will feed a growing and increasingly affluent and urban world
population. "This is a silver-bullet, industrial approach, not an
agro-ecosystem approach," Gurian-Sherman says. With a population of
glyphosate-resistant weeds already established in many places, it is
virtually certain that if dicamba and 2,4-D are used the same way, some
of the same weeds will evolve resistance to them as well. Then where
will we turn? There are only so many herbicide families, and chemical
companies are not developing new ones, because the returns are so much
better on genetic engineering of seeds. "I'm not opposed to genetic
engineering in principle, but where has it gotten us?" he asks.
"Billions in research have produced only two helpful traits [glyphosatc
resistance and Bt expression], whereas conventional techniques have
yielded insect , and disease resistance, drought tolerance and better
crop yields at a lower cost."

The solution, Gurian-Sherman argues, lies not with more expensive
technological fixes but with the kind of crop science that would have
been familiar to Gregor Mendel in the 19th century: incremental advances
in yield, drought resistance and fertilizer use. "We need a fundamental
shift in how we think about agriculture," he says, "and this isn't
getting us any closer to it." 5!

MORE TO EXPLORE

Failure to Yield: Evaluating the Performance of Genetically Engineered
Crops. Doug Gurian-Sherman. Union of Concerned Scientists, April 2009.

The Impact of Genetically Engineered Crops on Farm Sustainability in the
United States. Committee on the Impact of Biotechnology on Farm-Level
Economics and Sustainability, National Research Council. National
Academies Press, 2010.

SCIENTIFIC AMERICAN ONLINE

More sources on superweeds at
http://www.scientificamerican.com/ar...s-farming-thre
at-ragweed-forest
--
- Billy

Dept. of Defense budget: $663.8 billion
Dept. of Health and Human Services budget: $78.4 billion


Every gun that is made, every warship launched, every rocket fired signifies in the final sense, a theft from those who hunger and are not fed, those who are cold and are not clothed. This world in arms is not spending money alone. It is spending the sweat of its laborers, the genius of its scientists, the hopes of its children. This is not a way of life at all in any true sense. Under the clouds of war, it is humanity hanging on a cross of iron.
- Dwight D. Eisenhower, 16 April 1953

Send Monsanto after the superweeds?

In article ,
"Martin Riddle" wrote:

Send Monsanto after the superweeds?


If only the weeds had incorporated Monsanto's genes, then they would
belong to Monsanto. Unfortunately, the weeds have sorted out the problem
on their own, and have come up with their own unique responses to the
herbicides.


McGowan's Drinking Guide (Translated from the original German. It's
complicated, OK?)
Drinking Problems

Symptom Fault Action to be Taken

Everything has You have fallen As for falling over
gone dim, and you over forwards. backwards.
have a mouthfull of
cigarette butts and
broken teeth.
----

Are you better off than you were 30 years ago? 10 years ago? 1 year ago?

Thank Reaganomics/Thatcherism, a.k.a. Voodoo economics :O(
----

in the water bucket
********* a melon and an eggplant
***** nodding to each other
* ************* - * Yosa Buson
--
- Billy

Dept. of Defense budget: $663.8 billion
Dept. of Health and Human Services budget: $78.4 billion


Every gun that is made, every warship launched, every rocket fired signifies in the final sense, a theft from those who hunger and are not fed, those who are cold and are not clothed. This world in arms is not spending money alone. It is spending the sweat of its laborers, the genius of its scientists, the hopes of its children. This is not a way of life at all in any true sense. Under the clouds of war, it is humanity hanging on a cross of iron.
- Dwight D. Eisenhower, 16 April 1953

Billy wrote:
Scientific American, May 2011

AGRICULTURE
The Growing Menace from SUPERWEEDS
Pigweed, ragweed and other monsters have begun to outsmart
the advanced technologies that protect the biggest U.S. cash crops

i would not call it advanced,
instead it is quite retarded.


by Jerry Miller
....
THE MAKING OF KILLER RAGWEED
....
The solution, Gurian-Sherman argues, lies not with more expensive
technological fixes but with the kind of crop science that would have
been familiar to Gregor Mendel in the 19th century: incremental advances
in yield, drought resistance and fertilizer use. "We need a fundamental
shift in how we think about agriculture," he says, "and this isn't
getting us any closer to it." 5!

MORE TO EXPLORE
....
SCIENTIFIC AMERICAN ONLINE

More sources on superweeds at
http://www.scientificamerican.com/ar...s-farming-thre
at-ragweed-forest

absolutely no surprises in any
of this reading.


songbird