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原文： ISIS Report 01/02/10 GM Crops Facing Meltdown in the USA Majorcrops genetically modified for just two traits - herbicide toleranceand insect resistance are ravaged by super weeds and secondary pests inthe heartland of GMOs as farmers fight a losing battle with more of thesame; a fundamental shift to organic farming practices may be the onlysalvation Dr. Mae-Wan Ho Pleasecirculate widely, keeping all links unchanged, and submit to yourgovernment representatives demanding an end to GM crops and support fornon-GM organic agriculture Twotraits account for practically all the genetically modified (GM) cropsgrown in the world today: herbicide-tolerance (HT) due toglyphosate-insensitive form of the gene coding for the enzyme targetedby the herbicide, 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS),derived from soil bacterium Agrobacterium tumefaciens, and insect-resistance due to one or more toxin genes derived from the soil bacterium Bt (Bacillus thuringiensis). Commercial planting began around 1997 in the United States,the heartland of GM crops, and increased rapidly over the years. Bynow, GM crops have taken over 85-91 percent of the area planted withthe three major crops, soybean, corn and cotton in the US [1]] (see Table 1), which occupy nearly 171 million acres. The ecological time-bomb that came with the GM crops has been ticking away, and is about to explode.
HT crops encouragedthe use of herbicides, resulting in herbicide-resistant weeds thatdemand yet more herbicides. But the increasing use of deadly herbicideand herbicide mixtures has failed to stall the advance of the palmersuper weed in HT crops. At the same time, secondary pests such as thetarnished plant bug, against which Bt toxin is powerless, became thesingle most damaging insect for US cotton. Monster plants that can’t be killed
It is the Day of the Triffids - not thegenetically modified plants themselves as alluded to in John Wyndham’snovel - but “super weeds that can’t be killed” [2], created by theplanting of genetically modified HT crops, as seen on ABC TV news.
The scene is set at harvest time in ArkansasOctober 2009. Grim-faced farmers and scientists speak from fieldsinfested with giant pigweed plants that can withstand as muchglyphosate herbicide as you can afford to douse on them. One farmerspent US$0.5 million in three months trying to clear the monster weedsin vain; they stop combine harvesters and break hand tools. Already, anestimated one million acres of soybean and cotton crops in Arkansas have become infested.
The palmer amaranthor palmer pigweed is the most dreaded weed. It can grow 7-8 feet tall,withstand withering heat and prolonged droughts, produce thousands ofseeds and has a root system that drains nutrients away from crops. Ifleft unchecked, it would take over a field in a year.
Meanwhile in North Carolina Perquimans County,farmer and extension worker Paul Smith has just found the offendingweed in his field [3], and he too, will have to hire a migrant crew toremove the weed by hand.
The resistant weedis expected to move into neighbouring counties. It has alreadydeveloped resistance to at least three other types of herbicides.
Herbicide-resistance in weeds is nothing new. Ten weed species in North Carolina and 189 weed species nationally have developed resistance to some herbicide.
A new herbicide is unlikely to come out, said Alan York, retired professor of agriculture from North Carolina State University and national weed expertGlyphosate-resistant weeds from widespread planting of HT crops
Glyphosate is the most widely used herbicide in the USand the world at large. It was patented and sold by Monsanto since the1970s under the trade name and proprietary formulation, Roundup. Itspopularity shot up with the introduction of HT crops. Data from the USDepartment of Agriculture indicate that the use of glyphosate on majorcrops went up by more than 15 fold between 1994 and 2005 [4]. The EPAestimated in 2000-2001 that 100 million pounds of glyphosate are usedon lawns and farms every year [5], and over the last 13 years, it hasbeen applied to more than a billion acres [6].
It did not takelong for glyphosate-resistant weeds to appear, just as weeds resistantto every herbicide used in the past had appeared. The Weed ScienceSociety of America reported nine weed species in the United States withconfirmed resistance to glyphosate [6]; among them are strains ofcommon ragweed (Ambrosia artemisiifolia), common waterhemp (Amaranthus rudis), giant ragweed (Ambrosia trifida), hairy fleabane (Conyza bonariensis), horseweed (Conyza canadensis), Italian ryegrass (Lolium multiflorum), johnsongrass (Sorghum halepense), rigid ryegrass (Lolium rigidum), and palmer pigweed (Amaranthus palmeri).Glyphosate-resistant palmer super weed
Glyphosate-resistant palmer pigweed first turned up in late 2004 in Macon County, Georgia, and has since spread to other parts of Georgia as well as to South Carolina, North Carolina, Arkansas, Tennessee, Kentucky and Missouri [7]. An estimated 100 000 acres in Georgiaare severely infested with pigweed and 29 counties have now confirmedpigweed resistance to glyhosate, according to weed specialist StanleyCulpepper at the University of Georgia. In 2007, 10 000 acres of glyphosate-resistant pigweed infested land were abandoned in Macon County.
Monsanto’stechnical development manager Rick Cole was reported saying that theproblems were “manageable”. He advised farmers to alternate crops anduse different makes of herbicides. Monsanto sales representatives areencouraging farmers to mix glyphosate and older herbicides such as2,4-D, banned in Sweden, Denmark and Norway on account of links to cancer and reproductive and neurological damages. It is a component of Agent Orange used in Vietnam in the 1960s.
Farmers in Georgia are reported to be going back to conventional non-GM crops.
Weed scientists at the University of Georgia estimate that an average of just two palmer amaranth plants in every 6 mlength of cotton row can reduce yield by at least 23 percent [8]. Asingle weed plant can produce 450 000 seeds. Many fields in Arkansas, Tennessee, New Mexico, Mississippi and most recently, Alabama are also infested.
Paraquat isrecommended for use in conservation tillage programmes, mixed with upto three other herbicides, each with a different mode of action.Scientists at the University of Tennessee have seen palmer weeds resistant not only to glyphosate but also to the sulfonylurea herbicide trifloxysulfuron-sodiumGlyphosate resistance with the greatest of ease
Critics have beenpredicting glyphosate-resistant weeds before HT crops were introduced,simply through cross-pollination between HT crops and wild weedyrelatives. But they had neglected the ‘fluid genome’ mechanisms thatcan alter genomes and genes in response to environmental stimuli,enabling most weed plants to become herbicide resistant independentlyof cross-pollination. I drew attention to these mechanisms in my book Genetic Engineering Dream or Nightmare, the Brave New World of Bad Science and Big Business [9] first published in 1997/1998.
Researchers led by Todd Gaines at Colorado State University, Fort Collins in the United States investigated glyphosate-resistant palmer pigweed populations from Georgia.They found that the gene coding for the enzyme EPSPS responsible formetabolising glyphosate herbicide was amplified (multiplied) 5 to160-fold in glyphosate-resistant plants compared withglyphosate-susceptible plants [10]. The level of gene expression waspositively correlated with gene copy number. Fluorescent staining forthe gene showed that the amplified gene copies were present on everychromosome.
Geneamplification is one of the most common physiological responses ofcells and organisms to ‘selective’ agents in their environment, knownat least since 1980s [9].
Glyphosateresistance has been confirmed in 16 weed species as of 2009 [10]. Themechanisms identified so far include reduced glyphosate uptake, and/ormutations in the EPSPS gene that make it less susceptible to inhibitionby the herbicide. Glyphosate-resistant palmer pigweed is the first caseof resistance based on gene amplification. It confirms the ease withwhich resistance to obnoxious agents can evolve [9], and the futilityof this ‘chemical warfare’ against nature.Tarnished plant bug the single most damaging pest for cotton
The tarnished plant bug infested 4.8 million acres of UScotton in 2008 [11] making it the single most damaging pest for cotton.Another insect, the fleahopper ranked 5th, and infested 2.3 millionacres.
The Cotton Belt of the United States, extending from the San Joaquin Valley of California to Southeastern Virginia,has largely seen off the boll weevil and tobacco budworm since theintroduction of Bt cotton, which now accounts for 65 percent of thearea planted with cotton (Table 1 [1]). But, as in India and elsewhere [12, 13], secondary pests are posing serious problems, especially the tarnished plant bug.The tarnished plant bug (TPB), Lygus lineolaris,has been a cotton pest for as long as records were kept. Before 1995,it was controlled with insecticides targeting other insect pests suchas tobacco budworm and boll weevil. According to researchers at theMississippi State University Delta Research and Extension Center [14],since the widespread adoption of Bt-cotton and eradication of the bollweevil, less insecticide have been used; and as a result, the tarnishedplant bug has become the primary insect pest of cotton.
Additional insectcontrol costs are coming from increasing foliar sprays, highertechnology fees and pest resistance, said Jeff Gore, researchentomologist at the Delta Research and Extension Center, speaking at the 2010 Beltwide Cotton Conferences in New Orleans [15]
In 1995 planting anacre of cotton cost $12.75 to $24; in 2005, planting Bollgard, RoundupReady cotton with a ‘Cadillac’ seed treatment would have cost about $52an acre. Now in 2010, with Bollgard II and Roundup Ready Flex, farmerswill be spending $85 or more an acre.
“In Mississippi,we have growers who are spending well over $100 for foliar insectcontrol. You add that onto technology fees and seed treatments, youunderstand why our cotton acreage is decreasing.” Gore said.
To compound theproblem, TPB has become resistant to several classes of insecticides,particularly in the Delta regions of the Mid-South states [14].
While TPB is a pestof cotton throughout the growing season, it is particularly damagingduring the flowering period, when the pest reproduces copiously, soboth adult and immature stages of TPB feed on cotton during theflowering period. Most feeding occurs on reproductive structures. Thepests insert their mouthparts into squares and small bolls. It is notuncommon for TPB to cause near-total crop loss in the absence ofeffective control in some areas of the Delta.
Mid-South growersconsulted Gore about planting a non-Bt variety, especially with thehigher costs of Bt technology [15]. “We have a few growers plantingsmall acreages of non-Bt cotton, and they’re probably going to seebenefits from that.
“But if we startshifting back to non-Bt cotton, I promise you, the tobacco budworm willcome back, and we don’t want to be making foliar applications forresistant tobacco budworms, in addition to treating tarnished plantbugs. The amount of money we would have to spend in that situationwould be astronomical.”
TPB has been theNo. 1 pest in the Mid-South for the past four to five years, and isdriving a lot of cotton growers out of the Mississippi Delta, no longerable to afford the cost of sprays.
Gore revealed thatspider mites are also gaining a reputation as ‘budget busters’ in theSouth, along with aphids and stink bugs.
Like TPB, spidermites are becoming resistant to the insecticides used to control them.“Over the past 15 years, we’ve essentially doubled our applicationrates with Bidrin and tripled our application rates with acephate. Sowe’re not only spraying more often, we’re applying higher rates thatcost more.” Gore said.
He pointed out thata side-effect of relying on neoniccotinoids for plant bug control issome resistance has developed in cotton aphids. “We're starting to hearlots of complaints from consultants across the Mid-South.” More of the same is futile
It isdisappointing though predictable that the only official academic advicegiven to farmers is more of the same conventional practices thatcreated the problems in the first place, spraying more and sprayingmixtures of different kinds of pesticides, including those banned forbeing too toxic. Industry, meanwhile, is ready to sell varieties withmore stacked GM traits; up to eight at double the seed price [16].
Disappointingtoo is the persistent effort by some governments and governmentscientists to promote the failed GM technology, which as I made clear,was already obsolete since the early 1980s [9]. A Sciencexpresspaper (indicating quick publication, probably without peer review)entitled “Food security: the challenge of feeding 9 billion people”[17] co-authored by UK chief scientist Prof. John Beddington amongothers, while somewhat dismissive of current GM crops, neverthelessholds out promises we’ve heard for more than 30 years. “The next decadewill see the development of combinations of desirable traits and theintroduction of new traits such as drought tolerance. By mid-centurymuch more radical options involving highly polygenic traits may befeasible.” It went on to promise “cloned animals with engineered innateimmunity to diseases” and more.
Glyphosate andRoundup, still advertised as ‘less toxic to us than table salt’ in apamphlet from the Biotechnology Institute promoting HT crops as ‘WeedWarrior’ [18], is in fact highly toxic as new findings indicate [19,20] (Death By Multiple Poisoning, Glyphosate and Roundup, SiS 42; Ban Glyphosate Herbicides Now, SiS 43). Thirteen years of GM crops in the USA has increased overall pesticide use by 318 million pounds [21] (GM Crops Increase Herbicide Use in the United States, SiS 45). The extra disease burden on the nation from that alone is considerable.
India has learned bitter Lessons from Bt Cotton [22] in a saga of worsening farm suicides and, in common with the USA,an ecological disaster in secondary and new cotton pests, resistantpests, new diseases, and above all, soils so depleted in nutrients andbeneficial microorganisms that they would cease to support the growthof any crop in a decade. Their only salvation is a return to organicagriculture, which has already proven far more sustainable andprofitable than Bt cotton [12]. This may apply also to the USA.A fundamental shift in farming practices needed now
The organic market has been booming in the United Statesdespite the economic downturn. According to a new report from the USDepartment of Agriculture, retail sales of organic food went up to$21.1 billion in 2008 from $3.6 billion in 1997 [23] (see Fig. 1). Themarket is so active that organic farms have struggled at times toproduce sufficient supply to keep up with the rapid growth in consumerdemand, leading to periodic shortages of organic products.(Figure 1 Growth in US organic market 1997 to 2008)
Certified organicacres more than doubled from 1.3 million acres in 1997 to a little over4 million acres in 2005 (0.5 percent of all agricultural land in the US).In the same period, the number of organic farms increased from 5 021 to8 493, and the average size of certified organic farms went from 268acres to 477 acres.
So why are USfarmers failing to taking advantage of the rapidly expanding market? Itis thought [23] that potential organic farmers may opt to continue withconventional production methods because of “social pressures from otherfarmers nearby who have negative views of organic farming”, or becauseof an inability to weather the effects of reduced yields and profitsduring the transition period. This is not surprising on account of thepersistent negative propaganda carried out by GM proponents, includinggovernment regulatory agencies, against organic agriculture. (See forexample the recent attempt by UK Food Standards Agency to prove organicfood is no more nutritious than conventional food, which backfired [24](UK Food Standards Agency Study Proves Organic Food Is Better, SiS44). The usual claims are that organic agriculture yields less andrequire more energy than conventional agriculture, and organic produceno more nutritious or healthy, but less hygienic than conventionalproduce. These false claims are all thoroughly refuted in ISIS report Food Futures Now: *Organic *Sustainable *Fossil Fuel Free [25], with evidence from the published scientific literature, as well as other studies.
Most relevant forUS farmers is a study by Kathleen Delate of Iowa State University andCynthia A. Cambardella of the US Department of Agriculture assessingthe performance of farms during the three-year transition it takes toswitch from conventional to certified organic production [26]. Theexperiment lasting four years (three years transition and first yearorganic) showed that although yields dropped initially, they equalizedin the third year, and by the fourth year, the organic yields wereahead of the conventional for both soybean and corn.
Our report [25]also documents the enormous potential for reducing greenhouse emissions– even to the extent of freeing us entirely from fossil fuels – throughorganic agriculture and localised food (and renewable energy) systems.It is a unique combination of the latest scientific analyses, casestudies of farmer-led research, and especially farmers’ own experiencesand innovations that often confound academic scientists wedded tooutmoded and obsolete theories, of which GM technology is one glaringexample.
At about the sametime our report was released, the International Assessment ofAgricultural Knowledge, Science and Technology for Development (IAASTD)was also published. IAASTD was the result of three-year deliberation by
400participating scientists and non-government representatives from 110countries around the world [27]. It came to the conclusion that smallscale organic agriculture is the way ahead for coping with hunger,social inequities and environmental disasters [28] (“GM-Free Organic Agriculture to Feed the World[”, SiS 38).
A fundamental shift in farming practice is needed right now, before the agricultural meltdown is complete.References- Adoption ofngenetically engineered crops in the U.S.: Extent of adoption. USDA Economic Research Service, 1 July 2009, http://www.ers.usda.gov/Data/biotechcrops/adoption.htm
- Super weed can’t be killed, abc news, 6 October 2009, http://abcnews.go.com/Video/playerIndex?id=8767877
- “N.C. farmers battle herbicide-resistant weeds”. Jeff Hampton, The Virginian-Pilot. 19 July 2009, http://hamptonroads.com/2009/07/nc-farmers-battle-herbicideresistant-weeds
- Who benefits from gm crops? The rise in pesticide use, executive summary, Friends of the Earth International, Amsterdam, January 2008.
- 2000-2001 pesticide market estimates: usage, U.S. Environmental Protection Agency, http://www.epa.gov/oppbead1/pestsales/01pestsales/usage2001_3.htm
- Glyphosate-resistant weeds: can we close the barn door? Weed Science Society of America, 18 November 2009, http://www.wssa.net/WSSA/PressRoom/WSSA_GlyphosateResistance.pdf
- “’Superweed’ explosion threatns Monsanto heartlands”, Clea Caulcutt, 19 April 2009, http://www.france24.com/en/20090418-superweed-explosion-threatens-monsanto-heartlands-genetically-modified-US-crops
- “Paraquat fights glypohsate resistant palmer amaranth”, 30 September 2009,
http://paraquat.com/english/news-and-features/archives/paraquat-fights-glyphosate-resistant-palmer-amaranth - Ho MW. Genetic Engineering Dream of Nightmare? The Brave New World of Bad Science and Big Business,Third World Network, Gateway Books, MacMillan, Continuum, Penang,Malaysia, Bath, UK, Dublin, Ireland, New York, USA, 1998, 1999, 2007(reprint with extended Introduction). http://www.i-sis.org.uk/genet.php
- GainesTA, Zhang W, Wan D et al. Gene amplification confers glyphosateresistance in Amaranthus palmeri. PNAS Early Edition 2009,www.pnas.org/cgi/doi/10.1073/pnas.0906649107
- ARS survey helps growers track two key cotton pests. PHYSORG.com, 1 December 2009, http://www.physorg.com/news178912351.html
- Ho MW. Farmer suicides and Bt cotton nightmare unfolding in India. Science in Society 45 (in press)
- Ho MW. Mealy bug plagues Bt cotton in India and Pakistan. Science in Society 45 (in press)
- CatchotA, Musser F, Gore J, Cook D, Daves D, Lorenz G, Akin S, Studebaker G,Tindall K, Stewart S, Bagwell R, Leonard BR and Jackson R. MidsouthMulttistate Evaluation of Treatment Thresholds for Tarnished Plant Bug.2009, Mississippi State University Extension Service, http://msucares.com/pubs/publications/images/p2561_pics/bug_1.jpg
- “Insect control pushes cotton costs higher”, Elton Robinson, Farm Press, 15 January 2010, http://deltafarmpress.com/cotton/cotton-insect-control-0115/
- Benbrook C. Critical issue report: the seed price premium. The Organic Center. 2009 December. http://www.organic-center.org/reportfiles/Seeds_Final_11-30-09.pdf
- GodfrayHCJ, Beddington JR, Crute IR, Haddad L, Lawrence D, Muir JF, Pretty J,Robinson S, Thomas SM and Toulmin C. Food security: the challenge offeeding 9 billion people. Sciencexpress, 28 January2010/10.1126/science.1185383
- Weed Warrior Hebicide-Tolerant Crops, accessed 29 January 2010, http://www.biotechinstitute.org/resources/YWarticles/10.1/10.1.3.pdf
- Ho MW and Cherry B. Death by multiple poisoning, glyphosate and Roundup. Science in Society 42 , 14, 2009
- Ho MW. Ban glyphosate herbicides now. Science in Society 43, 34, 2009
- Cherry B. GM crops increase herbicide use in the United States. Science in Society 45 (in press)
- Ho MW. Lessons from Bt cotton. ISIS letter to Hilary Benn, UK Secretary of State for the Environment, 4 January 2010, http://www.i-sis.org.uk/lessonsFromBtCotton.php
- Marketing U.S.organic foods: recent trends from farms to consumers. Carolyn Dimitriand Lydia Oberholtzer, USDA Economic Research Service, September 2009, http://www.ers.usda.gov/Publications/EIB58/
- Ho MW.UK Food Standards Agency study proves organic food is better. Science in Society 44, 32-33, 2009.
- Ho MW, Burcher S, Lim LC, et al. Food Futures Now, Organic, Sustainable, Fossil Fuel Free, ISIS and TWN, London, 2008. http://www.i-sis.org.uk/foodFutures.php
- DelateK and Cambardella CA. Organic production: Agroecosystem performanceduring transition to certified organic grain production. Agronomy Journal 2004, 96, 1288-98.
- InternationalAssessment of Agricultural Knowledge, Science and Technology forDevelopment, IAASTD,2008http://www.agassessment.org/inde ... s_Materials&ItemID=11
- Ho MW. “GM-free organic agriculture to feed the world”. Science in Society 38, 14-15, 2008.
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