North Dakota State University
NDSU Extension Service
Volume 18, No. 1, January 2000
Alan Dexter, Weed Scientist
Crops that have been made resistant to herbicides through biotechnology techniques and crops that have had the Bt gene inserted for insect control were not grown commercially in 1995. These crops were widely grown in 1998 and 1999 and they had a large impact on pesticide use in some cases. The objective of this paper was to report the influence of herbicide resistant crops and Bt crops on pesticide use in the United States.
Corn, soybean and cotton are the crops with the greatest acreage of biotechnology modified varieties, so these three crops will be considered. The author did not conduct original surveys but obtained information from the National Center for Food and Agricultural Policy in Washington DC (NCFAP), the USDA National Agricultural Statistics Service (NASS), Doane Marketing Research (Doane), Monsanto, AgrEvo USA and American Cyanamid. Most pesticide use data are from 1998 since use data available for 1999 were limited when the paper was prepared. All values for pesticide use have been derived by totaling multiple treatments to the same acreage as multiple acres. Also, pesticides used in a tank-mix combination are totaled separately. Thus, reported pesticide use often exceeds 100% of planted acres.
Herbicide resistant corn was planted on 8% of the USA acreage in 1998 and on 7% of the acreage in 1999 (NASS). Herbicide resistant corn would include Roundup Ready (resistant to glyphosate), Liberty Link (resistant to glufosinate), and Clearfield (resistant to imidazolinones). The Clearfield corn is not transgenic while Liberty Link corn and Roundup Ready corn are transgenic. In 1995, 23 herbicides were applied on 229% of the corn acreage and the average total active ingredient (ai) applied was 2.6 lb/A. In 1998, 27 herbicides were applied on 242% of the acreage and the average total ai applied was 2.5 lb/A. Increased use of tank-mix combinations between 1995 and 1998 probably accounts for much of the increase in acres treated between 1995 and 1998.
Glyphosate use was similar in 1995 and 1998 (Table 1). Glyphosate use in 1995 was before corn emergence. Most of the glyphosate used on corn in 1998 also was preemergence since only about 1% of the corn acreage was Roundup Ready (Monsanto). Glufosinate was applied to 4% of the acreage in 1998, which agrees closely with an estimate from AgrEvo that 4% of the 1998 corn acreage was Liberty Link. AgrEvo estimated that 7% of the corn acreage was Liberty Link in 1999.
Table 1. Herbicide use in corn (NASS).
| ------------------------------------------------------------------------------ | ||
| Herbicide | 1995 | 1998 |
| ------------------------------------------------------------------------------ | ||
| - % of Acres Treated - | ||
| Glyphosate Glufosinate Imazethapyr Acetanilides Triazines Sulfonylureas Growth regulators All herbicides |
6 0 1 58 86 19 41 229 |
5 4 3 68 80 20 40 242 |
| ------------------------------------------------------------------------------ | ||
Imazethapyr was used on 3% of the corn acreage in 1998 suggesting that about 3% of the
acreage was Clearfield (Table 1). A small acreage of Clearfield corn was planted in 1995
and this accounts for imazethapyr on 1% of the acreage. Clearfield corn was called Imi
corn in 1995. American Cyanamid estimated that 4% of the 1999 corn acreage was Clearfield.
Acetanilide use increased and triazine use decreased from 1995 to 1998.
Bt corn for European corn borer control was planted on 24% of the USA acreage in 1998 and 27% of the acreage in 1999 (NASS). In 1995, nine insecticides were applied to 30% of the corn acreage and the average total ai applied was 0.7 lb/A. In 1998, 15 insecticides were applied to 36% of the acreage and the average total ai applied was 0.5 lb/A. The reduction in ai/A was probably due to new lower-rate insecticides.
Doane Marketing Research in the North Central Region of the United States showed a reduction in insecticide use on corn from 33% of the acres treated in 1998 to 28% of the acres treated in 1999. Prior to 1996, only about 2 to 5% of the corn acres were treated for European corn borer control. Other insects such as corn rootworm were the target of most insecticide applications, so the small influence of Bt corn on insecticide use in corn would be expected. Bt corn is planted on a much greater acreage than was ever treated with insecticide for European corn borer because yield comparisons between Bt corn and conventional corn have generally shown a significant yield advantage for the Bt corn. Naturally, the yield advantage varies with the level of European corn borer infestation.
Herbicide resistant soybean was planted on 41% of the acres in 1998 and on 56% in 1999 (NASS). Most of the herbicide resistant soybean would be Roundup Ready (glyphosate resistant) but a small acreage was STS with increased resistance to sulfonylurea herbicides. In 1995, 27 herbicides were applied on 265% of the soybean acreage and the total ai applied was 1.1 lb/A.
In 1998, 31 herbicides were applied on 205% of the acreage and the total ai applied was 1.1 lb/A. Glyphosate was applied preemergence to soybean on 20% of the soybean acres m 1995 and was applied preemergence or postemergence to 46% of the acres in 1998 (Table 2). Probably most of the glyphosate in 1998 was postemergence rather than preemergence since Monsanto observed a large reduction in preemergence or burndown glyphosate after introduction of Roundup Ready soybean.
Table 2. Herbicide use in soybean (NASS).
| ------------------------------------------------------------------------------ | ||
| Herbicide | 1995 | 1998 |
| ------------------------------------------------------------------------------ | ||
| - % of Acres Treated - | ||
| Glyphosate DNA's Imadazolinone Fops and Dims (POST grass) Sulfonylureas Diphenylethers Acetanilides Bentazon Metribuzin All herbicides |
20 47 59 34 28 21 12 12 11 265 |
46 34 32 21 17 15 8 7 6 205 |
| ------------------------------------------------------------------------------ | ||
The soybean acres treated by all other families of herbicides declined from 1995 to 1998
(Table 2). For all herbicides, fewer soybean acres were treated in 1998 than 1995 and the
reduction would be 60% of the 72.4 million soybean acres planted in 1998 or 43.4 million
fewer acres treated with herbicide. Also, prices of soybean herbicides have been reduced
from 1995 to 1998 50 the impact on income from herbicide sales has been influenced by more
than just the reduction in acres treated. Glyphosate is generally used without an added
adjuvant while many of the herbicides replaced need an added adjuvant, so the change in
herbicide use has also affected adjuvant sales.
Herbicide resistant cotton was planted on 26% of the USA acreage in 1998 and on 35% of the acreage in 1999 (NASS). Herbicide resistant cotton would include Roundup Ready (resistant to glyphosate) and BTX (resistant to bromoxynil). In 1995, 16 herbicides were applied on 254% of the cotton acreage and the average total ai applied was 1.9 lb/A. In 1999, 21 herbicides were applied on 257% of the cotton acreage and the average total ai applied was 1.8 lb/A.
Glyphosate was applied preemergence to cotton on 9% of the acres in 1995 and was applied preemergence or postemergence to 30% of the acres in 1998 (Table 3). Bromoxynil was not used on cotton in 1995 and was used on 4% of the acres in 1998. This suggests that Roundup Ready cotton was on 22% and BTX cotton was on 4% of the total cotton acres to make up the 26% herbicide resistant acreage. Glyphosate was applied to 30% of the cotton acreage and glyphosate is normally used only once on cotton, so the use of preemergence glyphosate must have been similar in 1998 and 1995 at 8 to 9% of the acres.
Table 3. Herbicide use in cotton (NASS).
| ------------------------------------------------------------------------------ | ||
| Herbicide | 1995 | 1998 |
| ------------------------------------------------------------------------------ | ||
| - % of Acres Treated - | ||
| Glyphosate Bromoxynil DNA's Ureas MSMA Pyrithiobac Prometryne Norflurazon All herbicides |
9 0 81 45 22 0 30 15 254 |
30 4 81 52 20 16 15 5 257 |
| ------------------------------------------------------------------------------ | ||
Prometryne and norfiurazon use dropped considerably and use of urea herbicides and
pyrithiobac increased from 1995 to 1998 (Table 3). Total herbicide use was similar from
1995 to 1998. The average cost for herbicides in cotton was $21/A in 1995 and $25/A in
1998 (Doane).
Bt cotton for control of cotton bollworm and tobacco budworm was planted on 18% of the USA acreage in 1998 and on 25% of the acreage in 1999 (NASS). In 1995, 34 insecticides were applied to 270% of the cotton acreage and the average total ai applied was 1.8 lb/A. In 1998, 38 insecticides were applied to 170% of the acreage and the average total ai applied was 1.3 lb/A. Insecticides were used, on average, one less time per acre in 1998 than in 1995 and the average amount of insecticide applied was 0.5 lb/A less.
Cotton was grown on 13.4 million acres in 1998, so insecticides were applied to 13.4 million fewer acres and 6.7 million pounds of insecticides were not applied in 1998 as compared to what would have been applied using 1995 insecticide use levels. This change from 1995 to 1998 is primarily from the use of Bt cotton.
The average cost of insecticides on all cotton acres was $41.10/A in 1995 and was $27.80/A in 1998 (Doane). Assuming that this savings in insecticide cost was on the 2.5 million acres of Bt cotton, the savings in insecticides cost was $72/A in 1998. The technology fee for Bt cotton was $32/A. Comparisons of Bt cotton with conventional cotton in the southeast United States indicated a small yield advantage to Bt cotton of about 4% (NCFAP).
The adoption of seeds containing traits derived through biotechnology has had the greatest impact on reducing insecticide use in cotton and on shifting herbicide use in soybean. Bt corn has increased corn yield but did not have a noticeable effect on insecticide use in 1998. Changes in herbicide use were minor in corn from 1995 to 1998 due to herbicide resistant corn varieties, but this technology was just starting to be adapted in 1998 and adoption could increase in the future. Cotton herbicide products shifted from 1995 to 1998 but the total acres treated with herbicides remained similar and the dollars per acre spent on herbicides increased.
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Editors Note: The following article comes from the Maine Board of Pesticide Control. It outlines the controversy and dilemma policy makers face in dealing with pesticides and people who may be sensitive to them in minute quantities.
It's an affliction so mired in controversy that medical researchers, practitioners and patients dispute even its name. Environmental Illness, Universal Allergy, 20th Century Disease, Chemical Hypersensitivity Syndrome, Total Allergy Syndrome and Cerebral Allergy....These are just some of the terms which have in the past referred to an illness in persons who suffer from varied symptoms—some debilitating—which they attribute to their intolerance of chemicals.
Today sufferers, their advocates and some physicians call it Multiple Chemical Sensitivity (MCS). Others call it Idiopathic Environmental Intolerance, a name resulting from a World Health Organization workshop on the subject in 1996. There, conferees representing several scientific medical groups wrote in a position statement that the term MCS makes unsupported judgments on both the cause behind the symptoms—namely the chemicals—and the mechanisms
Whatever the term (let's settle for MCS), the disorder is unpleasant. Symptoms range from flu-like ailments, irregular heart beat, muscle spasms, skin disorders, difficulty breathing, and fatigue to disorientation, anxiety, loss of concentration, memory loss, irritability, insomnia, migraines, and depression.
In most cases, sufferers are afflicted with one or a few discomforting symptoms. For some, however, symptoms can incapacitate. Parents may need to home-school their MCS children while adult sufferers are driven from the workplace or rendered unable to work altogether. In extreme cases, individuals call themselves "environmental hostages," taking refuge within the confines of their sanitized homes or in remote chemical-free settings.
MCS sufferers generally attribute their illness to environmental chemicals following either a major exposure or repeated exposures at low levels. Culprit agents include paints and solvents, office and carpet chemicals, petroleum products, fiberboard glue, preservatives, perfumes and pesticides. Onset of the illness is also attributed to anesthesia, pregnancy, extreme stress and courses of various drugs.
Following initial exposure(s), MCS sufferers report symptoms triggered by extremely low doses of exposure to chemicals normally tolerated by most of the population. These chemicals need not be related to each other or to those which initiated the disorder.
Leading efforts to show MCS to be a neurobiological disorder are Iris Bell of University of Arizona Health Sciences Center and Claudia Miller of University of Texas Heath Science Center. They and other investigators say MCS is caused by a dysfunctional relationship between the nervous and immune systems.
Most suspect on the neurological side is the interaction between the olfactory nerve responsible for the sense of smell and the portion of the brain known as the limbic system. This system affects emotions—among them anxiety and the innate flight-or-fight response.
Bell argues that the compromised immune system of sensitive persons allows the olfactory-limbic pathways to more readily trigger a seizure-like firing of nerve cells elsewhere in the brain. Sensitivity of portions of the brain can be enhanced by genetic endowment, stress, hormonal variations or nutrition, and, yes, prior environmental exposures. So when commanded by the olfactory nerve, these parts of the brain will elicit MCS symptoms—even when encountering minute levels of chemical stimuli. Miller adds, "the rich neural connections between the olfactory and limbic systems affect potentially every aspect of human physiology and behavior."
Skeptics—and there are many—say MCS victims can make the disorder into whatever they want, thanks to Bell and Miller's theories and the reinforcement of others who diagnose connections between illness and ecology. Scientific groups such as the American Academy of Allergy and Immunology, the California Medical Association, the American College of Physicians, and the American College of Occupational and Environmental Medicine say such MCS theories lack scientific foundation in toxicology or pharmacology. Without measurable physiological evidence of cause and effect, these critics argue, MCS is merely a name in search of a disease.
Mainstream medicine does recognize that individuals labeled with MCS are clearly distressed and that many are functionally disabled. It is explained, however, to be a potpourri of symptoms resulting from a conditioned response or other psychologically based disorders.
Skeptics offer alternative theories: 1) MCS may be triggered by low-level environmental chemical exposures, but that the sensitivity begins with psychological stress, 2) MCS is a misdiagnosed physical or psychological illness and chemicals are not the cause, and 3) MCS is an illness belief system that is maintained by a medical subculture of support groups, hotlines, journals and clinics which reinforce these beliefs.
Whatever its origins, MCS critics tell clinicians to treat symptoms as if they were physiologically based. Universally accepted data do show exposure to volatile organic compounds at levels far below those usually associated with toxicity to the central nervous system may indeed trigger symptoms consistent with panic attacks and depression. For this reason, skeptics urge physicians to provide care in ways that avoid assumptions that symptoms are all in the patient's head.
MCS advocates support arguments that mental disorder plays an important role in MCS symptoms. Since the brain is the seat of all emotions, it should come as no surprise that depression, anxiety and disorientation become credible symptoms of a neurological reaction to external chemical insults.
With both camps appreciating the mind can powerfully induce physical disorders, advocates and doubters concur research is needed to test MCS theories. They share also another opinion: each says the other guy's science is flawed.
As proof for their views, MCS advocates have offered tests such as emission tomography. This tool maps degrees of blood and glucose deprivation in the brains of MCS victims after chemical exposure.
Detractors say these tests are invalid. Without an appropriate test universe as well as experimental and control groups studies, these findings show nothing but the consequences of MCS, not the causes.
Instead, the medical establishment supports the many findings which point at the psychological basis for MCS. They also call for use of environmental challenge chambers that are double-blinded and placebo-controlled for testing specific outcome measures after low-level chemical exposure.
The recent discovery of rodent models—mice and rats which imitate MCS-like symptoms—has been lauded by both sides of the debate, but each accuses the other of pursuing this research at a glacial pace. MCS advocates say mainstream medicine has been bought by the chemical industry, government worker disability and insurance interests that wish to prevent MCS from becoming established by law as a bona fide disease. The medical establishment counters that MCS advocates are padding their own comfortable industry by allowing today's scientific vacuum to be filled by political definitions.
The Maine Board of Pesticide Control (MBPC) is faced with several challenges as a regulatory agency. While recognizing pesticides as valuable tools of agriculture, forestry and other industries, the regulatory panel is also charged with protecting the welfare of Maine's citizens and their environment.
Since the MBPC has no research resources of its own, it must rely upon a consensus of science to determine when pesticide risks outweigh their benefits.
At the same time, the panel hears Maine citizens—listening for opportunities to find a middle ground between pesticide users and concerned neighbors.
Increasingly, citizens have come forward to the MBPC with MCS complaints. Some claim to be so sensitive they require family members or legal representation to speak publicly on their behalf for fear of encountering a chemical exposure.
Imagine the potential line of questioning—some seemingly harsh—in the mind of each MBPC member when addressing MCS issues:
Until the medical community finds more agreement on this disorder, regulators like the MBPC will be squeezed somewhere between objective inaction and subjective policy making. There, a middle ground may be awfully hard to find.
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Testing
Date Category Location Time Available
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Jan. 18 Ornamental & Bismarck (Radisson) 8am-4:30 pm N
Turf
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Jan. 24 Fumigation Minot (Research & 8am-Noon, Train Y
Extension Center) 1pm-5pm, Test
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Jan. 25 Fumigation Fargo (NDSU Alumni 8am-Noon, Train Y
Center) 1pm-5pm, Test
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Feb. 7-9 Ground Core, Fargo (NDSU Alumni 7th: 1pm-5pm Train Y
Aerial, AgPest, Center) 8th: 8:30am-4:30pm
Right-of-Way, Train, (6pm-7:30pm
Research & Demo, optional study
Seed Treatment session)
9th: 8am-5pm, Test
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Feb. Ground Core, Minot (Research 22nd: 1pm-5pm Train Y
22-24 Aerial, AgPest, & Extension Center) 23rd: 8:30am-4:30pm
Right-of-Way, Train; (6pm-7:30pm
Research & Demo, optional study
Seed Treatment session)
24th: 8am-5pm, Test
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Mar. 6-8 ND Aerial Applicators Assoc. Convention Aerial Applicators only!
AgPest, Fargo (Ramada) 6th: 7am-8am and Y
Right-of-Way, 1pm-2pm,
Research & Demo, Registration;
Seed Treatment 2pm-5pm, Train
7th: 8:00am-4:30pm,
Train
8th: 8am-5pm, Test
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Mar. 21 Fumigation Dickinson (Travel 8am-Noon, Train Y
Lodge Hotel) 1pm-5pm, Test
-----------------------------------------------------------------------------
Mar. 22 Fumigation Carrington 8am-Noon, Train Y
(Research & 1pm-5pm, Test
Extension Center)
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Mar. Ground Core, Williston (Research 27th: 1pm-5pm Train Y
27-29 Aerial, AgPest, & Extension Center) 28th: 8:30am-4:30pm
Right-of-Way, Train; (6pm-7:30pm
Research & Demo, optional study
Seed Treatment session)
29th: 8am-5pm, Test
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Date Category Location Time
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Jan 18 Ornamental & Turf, Bismarck 8am-3:30pm
Greenhouse (Radisson)
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Jan 24 Fumigation Minot (Research & 8am-Noon
Extension Center)
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Jan 25 Fumigation Fargo (NDSU 8am-Noon
Alumni Center)
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Feb 16 Ground Core, Aerial, Park River 8am-3:30pm
AgPest, Right-of-Way, (Walsh County
Research & Demo, Ext. Bldg)
Seed Treatment
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Feb 18 Ground Core, Aerial, Fessenden 8am-3:30pm
AgPest, Right-of-Way, (KLT Office
Research & Demo, Building - Meeting
Seed Treatment Room)
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Feb 24 Ground Core, Aerial, Minot 8am-3:30pm
AgPest, Right-of-Way, (Ward County
Research & Demo, Courthouse - Ex
Seed Treatment Servicemen's Room)
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Feb 29 Ground Core, Aerial, LaMoure 8am-3:30pm
AgPest, Right-of-Way, (Omega Mall)
Research & Demo,
Seed Treatment
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Mar 1-2 Must attend both days
Ground Core, Aerial, Grand Forks 1st: 8am-10am
AgPest, Right-of-Way, (Civic Center) plus SGI program
Research & Demo, 2nd: 9am-10am
Seed Treatment plus SGI program
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Mar 7 ND Aerial Applicator Assoc. Convention
Aerial, AgPest, Fargo Pre-registration
Right-of-Way, (Ramada) 7am-8am,
Research & Demo, Training:
Seed Treatment 8am-Noon and
2pm-4pm
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Mar 14 Ground Core, Aerial, Mandan 8am-3:30pm
AgPest, Right-of-Way, (Seven Seas)
Research & Demo,
Seed Treatment
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Mar 20 Ground Core, Aerial, Dickinson 8am-3:30pm
AgPest, Right-of-Way, (Travel Lodge Hotel)
Research & Demo,
Seed Treatment
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Mar 21 Fumigation Dickinson 8am-noon
(Travel Lodge Hotel)
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Mar 22 Fumigation Carrington (Research 8am-noon
& Extension Center)
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Mar 23 Ground Core, Aerial, Devils Lake 8am-3:30pm
AgPest, Right-of-Way, (Ramsey County
Research & Demo, Courthouse -
Seed Treatment Meeting Room)
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Mar 23 Ground Core, Aerial, Alexander 9am-4:30pm
AgPest, Right-of-Way, (City Hall)
Research & Demo,
Seed Treatment
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Mar 29 Ground Core, Aerial, Williston 8am-3:30p.m.
AgPest, Right-of-Way, (Williams County
Research & Demo, Courthouse -
Seed Treatment Meeting Room)
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Apr 11 Ground Core, Aerial, Watford City 9am-4:30pm
AgPest, Right-of-Way, (McKenzie Weed
Research & Demo, Board Shop -
Seed Treatment SW Watford City)
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Apr 13 Ground Core, Aerial, Fargo (NDSU 8am-3:30pm
AgPest, Right-of-Way, Alumni Center)
Research & Demo,
Seed Treatment
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Fargo, ND, 58105-5051or Fax to: (701)231-8474
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| Back to Contents |
Pesticide Quarterly, Volume 18, No. 1, January 2000
NDSU Extension Service, North Dakota State University of Agriculture and Applied
Science, and U.S. Department of Agriculture cooperating. Sharon D. Anderson, Director,
Fargo, North Dakota. Distributed in furtherance of the Acts of Congress of May 8 and June
30, 1914. We offer our programs and facilities to all persons regardless of race, color,
national origin, religion, sex, disability, age, Vietnam era veterans status, or sexual
orientation; and are an equal opportunity employer.
This publication will be made available in alternative format for persons with
disabilities upon request 701/231-7881.
North Dakota State University
NDSU Extension Service