Weeds showing herbicide resistance
Daniel D. Worley (email@example.com)
Mon, 23 Feb 1998 06:33:08 -0400
>Date: Sat, 21 Feb 1998 12:07:20 -0500
>From: Richard Wolfson <firstname.lastname@example.org>
>Subject: Weeds showing herbicide resistance
>Here is an excellent article that I was forwarded about the development of
>herbicide resistant weeds. This is a major concern resulting from the use
>of herbicide resistant crops, which are one of the biggest categories of
>genetically engineered crops.
> May 27, 1997, The Des Moines Register
> Weeds showing herbicide resistance
>By GEORGE ANTHAN;
>WASHINGTON -- The hot, dusty, backbreaking job of weeding farm fields with
>hoe or by hand pretty much ended in American agriculture with the arrival
>of chemical herbicides after World War II. This technology and the machines
>that helped implement it revolutionized food production in the United
>States and elsewhere.
>They led to the huge increases in agricultural productivity that have kept
>a world whose population has doubled in 50 years from experiencing the
>widespread famines predicted by English economist Thomas Malthus.
>The technology also made millions of farmers unnecessary. Where a farm
>family once could work only about 160 acres, and then only with plenty of
>children to do hand weeding, a single farmer now routinely can handle 1,000
>acres or more.
>Yet, scientists -- and farmers -- are beginning to ask: "Are weeds staging
>a comeback?" There are reports that more and more weed species have
>developed resistance to many herbicides.
>The Environmental Protection Agency last year stated that 270 weed species
>were reported to have developed pesticide resistance. This compared with 48
>species identified as resistant in a 1986 National Academy of Sciences
>Monsanto Co. is studying a report that a type of rye grass in Australia has
>developed resistance to its widely used Roundup herbicide. Company
>officials have emphasized that up to now there have been no proven cases of
>weed resistance to Roundup, which uses the chemical compound glyphosate.
>"Weed resistance to herbicides has taken off," said Charles Benbrook, a
>Washington consultant who is a former official of the National Academy's
>Board on Agriculture. Benbrook long has advanced non-chemical pest-control
>In its report 11 years ago, the academy warned that "literally hundreds of
>species of insects, plant pathogens, rodents and weeds have become
>resistant to chemical pesticides. Indeed, resistance to pesticides is a
>global phenomenon. It is growing in frequency and stands as a reminder of
>the resiliency of nature."
>Douglas Buhler, research agronomist at the Agriculture Department's
>National Soil Tilth Laboratory in Ames, Iowa, agreed: "The key point is the
>resiliency of nature. We have thought that by using pesticides we could
>outfox nature. And we're not."
>Robert Gordon Harvey, professor of agronomy at the University of Wisconsin,
>said, "We're seeing worldwide a greater number of instances of
>Harvey said a major reason is the emphasis in recent decades on growing the
>same crop in the same fields year after year, referred to as "monoculture."
>"As we've gone to monoculture, we've produced a very inefficient ecosystem.
>If you have only corn in a field, nature says there's room for other plant
>species in that environment."
>Harvey said, "There are a lot of opportunities to manage weeds, but we have
>to be proactive." He advises farmers to have a five-year weed management
>plan that can include crop rotations, cultivation and a rigorous schedule
>both for application of chemicals and for the types of herbicides applied.
>Harvey said weed resistance is a perfect example of nature's persistence.
>Weeds, he said, for centuries have been able to resist man's control
>measures. He noted that in India, women are sent into the fields
>periodically to pull a certain noxious weed, which could be identified by
>its red stem. The women methodically pulled all red-stemmed plants.
>"But the weed adapted," said Harvey. "It developed a green stem. The key to
>weed control is not to use the same process too many times in a row."
>Ray McAllister, director of regulatory affairs for the American Crop
>Protection Association, which represents pesticide manufacturers, agrees
>that use of different herbicides, crop rotations and application of
>"integrated pest management" (often using non-chemical controls) is
>McAllister said resistance "is inevitable, given the way plants evolve."
>McAllister added that new, highly active, low-dose herbicides can result in
>minor genetic changes in weeds that can "make plants resistant to those
>herbicides." He said the overall situation is one the industry has
>"anticipated, planned for and worked around. We do that with a weed-control
>strategy that uses a variety of herbicides, watches for development of
>resistance" and emphasizes "planning alternative control strategies."
>McAllister said chemical companies "are the first to tell the farmer,
>'Don't use this product two or three years in a row.' Crop rotations, which
>enable you to break up the ... life cycle of weeds, and integrated pest
>management are absolutely essential."
>But Harvey, the University of Wisconsin scientist, said, "There's a
>continued reluctance among growers and chemical manufacturers to engage in
>or encourage practice of sound resistance management."
>He contends, "Short-term profits seem to take precedence," although Harvey
>said he sympathizes with a farmer "faced with a note due at the bank," who
>seeks to maximize his immediate output instead of trying to prevent a
>Lisa Drake, public affairs director for Monsanto, emphasized that "to this
>point, we have not verified field resistance to Roundup. But, having said
>that, we are a science-based company. We're very interested in
>understanding the phenomenon of resistance."
>Drake said: "Two or three times a year, we get calls of a particularly
>tough weed alleged to be resistant. We always do the same thing. We get
>some of the weed and we test it out."
>Scientists also are concerned that crops genetically engineered to resist
>herbicides or plant viruses -- such as Monsanto's soybean and Asgrow Seed
>Co.'s squash -- could promote weed resistance if the crops's resistant
>genes escape to weeds, creating an especially hardy variety of the wild
>Eric Johnson of Monsanto said the development of soybeans that resist
>Roundup and thus allow farmers to spray weeds without worrying about
>damaging their crop "actually provides a new tool for managing weeds."
>Fourteen leading agricultural chemical companies have formed the Herbicide
>Resistance Action Committee to help develop "effective, reliable, practical
>and economical" strategies to deal with weed resistance.
>At the same time, the committee says that while many hundreds of cases of
>resistance have been documented worldwide, "only under exceptional
>circumstances has resistance become a limiting factor for crop production,
>and then only on a local basis. ... "
>Robert Zimdahl, a professor of weed science at Colorado State University,
>summed up the resistance concerns in a 1992 essay for a USDA symposium on
>pesticides: "For most of the Western world's history, we have gloried in
>our Promethean power -- the power of science."
>In ancient Greek lore, Prometheus stole fire from the heavens and gave its
>energy to man. But, he continued, "for all its wonders and undeniable
>benefits, science and its associated technology have a disquieting aura of
>fallibility. Pandora may be a more important part of our inheritance than
>Pandora, also a figure in Greek mythology, opened a forbidden box and let
>out all the evils that have since afflicted mankind.
>Richard Wolfson, PhD
>Consumer Right to Know Campaign,
>for Mandatory Labelling and Long-term
>Testing of all Genetically Engineered Foods,
>500 Wilbrod Street
>Ottawa, ON Canada K1N 6N2
>Our website, http://www.natural-law.ca/genetic/geindex.html
>contains more information on genetic engineering as well as
>previous genetic engineering news items
>Subscription fee to genetic engineering news is $35 for 12 months
>See website for details.
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