NCFAP Cotton Case Study Summaries

A National Center for Food and Agricultural Policy study of biotechnology, which included three cotton case studies, documented that transgenic crops help Americans reap an additional 14 billion pounds of food and improve farm income $2.5 billion, while using 163 million fewer pounds of pesticide.

Published: July 9, 2002
Updated: April 5, 2017

The following three case studies were among 40 case studies of 27 crops compiled by the National Center for Food and Agricultural Policy (NCFAP) that documented that hardier crops developed through biotechnology can help Americans reap an additional 14 billion pounds of food and improve farm income $2.5 billion, while using 163 million fewer pounds of pesticide.

To view the full NCFAP report go to: http://www.ncfap.org/40CaseStudies.htm

32. Insect Resistant Cotton (1)

Bt cotton varieties were introduced in 1996, providing control of three major cotton insect pests: tobacco budworm, cotton bollworm and pink bollworm. These varieties offer an alternative to conventional insect spray programs. Tobacco budworm infestations were particularly heavy in 1995, causing severe yield loss in some areas. The worst damage was sustained by Alabama growers, who on average experienced a 29% yield loss due to bollworm/ budworm despite seven insecticide applications. These losses were attributed to the ineffectiveness of pyrethroid insecticides against budworm, due to the development of resistant populations in some states.

The adoption of Bt varieties was extremely rapid in states that experienced resistance problems (Arizona, Alabama, Georgia, Florida). After the year of very high budworm populations and damage in 1995, growers in Alabama adopted the new technology at an extremely rapid rate, planting over 60% of total acreage to Bt varieties in 1996. Bt cotton is credited with saving the cotton industry in Alabama. In 2001, 42% of cotton acreage in the United States was in Bt varieties. Adoption has been low in California (5%) because the worm pests are not a problem in the San Joaquin Valley and because California’s unique cotton cultivars have not been converted to Bt. Adoption was accelerated in certain states (Mississippi, Louisiana, Texas, Oklahoma, Arkansas, and Tennessee) due to implementation of Boll Weevil Eradication Programs (BWEP) and resistance problems experienced in 1995. Growers in BWEP areas are advised to plant Bt cotton due to the effects of the weevil sprays on predators of bollworms/budworms.

The impacts of the adoption of Bt cotton varieties include a reduction in yield losses due to Bt target pests, reductions in insecticide use, and cost savings. Numerous surveys have found that growers are achieving higher yields and attaining higher profits by planting Bt varieties, due to better pest control and decreased insect control costs. The average increase in net income in 2000, comparing Bt to conventional varieties, was $20/ acre, taking into account the technology fee. On average, per acre insect control costs were $2 higher. This increased cost was outweighed by a yield increase of 36 lbs/ acre.

In recent years, the bollworm/budworm has become significantly less troublesome in the Southeast (Georgia, Alabama, Florida) narrowing the economic difference between Bt and nonBt acreage.

Estimated Impacts of Insect Resistant Transgenic Cotton (1)
Change in Production: 185 million lbs/ yr increase in production
Change in Pesticide Use: 1.9 million lbs/ yr decrease in insecticides
Change in Net Revenue: $ 103 million/ yr increase in net revenue

Contacts:
Michael Williams, Mississippi State University 601-325-2986
Email: Mwilliams@entomology.msstate.edu

Jack Bacheler, North Carolina State University 919-515-8877
Email: jack_bacheler@ncsu.edu

Full Report: Plant Biotechnology: Current and Potential Impact For Improving Pest Management In U.S. Agriculture: An Analysis of 40 Case Studies by Leonard P. Gianessi, Cressida S. Silvers, Sujatha Sankula and Janet Carpenter
National Center for Food and Agricultural Policy, June 2002.

33. Insect Resistant Cotton (2)

The fall armyworm, soybean looper and the beet armyworm are destructive migratory pests of many crops in the southeastern US. Damage caused by fall armyworms on cotton is from their feeding on the fruit. Once loopers begin feeding on the outer canopy, they can completely defoliate the plant in 36 to 48 hours. Young beet armyworm larvae feed together and gradually disperse as they grow. They skelotenize leaves.

Transgenic Bt cotton has been commercially available in the United States since 1996. Bt cotton has demonstrated remarkable control of some lepidopteran pests, particularly the tobacco budworm and the pink bollworm. Since its release into commercial markets, Bt cotton seldom, if ever, has required supplemental insecticide control for these two pests. Control of the bollworm has been less dependable. Common lepidopteran pests such as fall armyworms, beet armyworms and soybean loopers are even more tolerant than bollworms. Supplemental foliar insecticide applications have been used in many Bt cotton fields to control economically damaging populations of fall armyworms, beet armyworms, soybean loopers and especially bollworms. Approximately 36% of current Bt cotton acreage is treated for bollworms (1.9 million acres) with 527,700 pounds of chemical active ingredients.

Approximately 65000 bales valued at $19 million were lost to bollworms on Bt cotton acreage in 2000. For beet armyworm/fall armyworm/soybean looper control, approximately 21% of current Bt cotton acreage is treated with 458,955 pounds of chemical active ingredients. Approximately 12,000 bales valued at $3.6 million were lost to loopers/armyworms on Bt cotton acreage in 2000.

Unacceptable control of bollworms and other lepidopteran pests such as beet armyworms, fall armyworms and soybean loopers, prompted the development of a new genetically modified cotton that contains two separate crystalline proteins. The addition of a second Bt protein provides satisfactory control of beet armyworms, fall armyworms, and soybean loopers. Efficacy is improved against bollworms. The dual-toxin cultivars may not require supplemental insecticide applications for these pests.

Bt cotton I will likely be phased out and completely replaced with Bt cotton II; a process that will take several years. It is estimated that Bt cotton II will be adopted on the same acreage that is currently planted with Bt cotton I at an increased cost of $2/A. The major impact of Bt cotton II would be an elimination of current losses and spraying costs due to bollworms/loopers/armyworms on Bt cotton acreage.

Estimated Impacts of Insect Resistant Transgenic Cotton (2)
Change in Production: 37 million lbs/ yr increase in production
Change in Pesticide Use: 1.0 million lbs/ yr decrease in insecticides
Change in Net Revenue: $ 46 million/ yr increase in net revenue

Contacts:
Michael Williams, Mississippi State University, 601-325-2986
Email: mwilliams@entomology.msstate.edu

Ralph Bagwell, Louisiana State University 318-435-2182
Email: rbagwell@agctr.lsu.edu

Full Report: Plant Biotechnology: Current and Potential Impact For Improving Pest Management In U.S. Agriculture: An Analysis of 40 Case Studies by Leonard P. Gianessi, Cressida S. Silvers, Sujatha Sankula and Janet Carpenter National Center for Food and Agricultural Policy, June 2002.

 

34. Herbicide Tolerant Cotton

Weeds can cause significant losses in cotton and require careful management by the grower. During the initial period of establishment, usually the first 6 to 8 weeks after planting, control of weeds is important in order to prevent undue stress upon the cotton seedlings. Weeds, if allowed to grow unchecked, can dramatically reduce cotton yields.

In 1995, the typical US cotton acre was treated with an average of nearly three active ingredients in nearly three treatments. There were also three cultivations made on the typical acre. Extensive use of hand-weeding crews has been utilized. In the early 1990s, 21% of US cotton acreage was handweeded annually with the highest use in California where 75% of the acreage was handweeded.

US cotton growers applied nearly 32 million pounds of active ingredients at an annual cost of $302 million just prior to introduction of transgenic herbicide tolerant cotton varieties. The total cost of weed control including herbicide, handweeding, cultivation and application costs was $797 million/yr.

BXN cotton varieties were introduced in 1995, offering cotton growers a cultivar resistant to bromoxynil (Buctril) a postemergence herbicide that kills may broadleaf plants. Roundup Ready cotton varieties were introduced in 1997. These varieties have been developed to tolerate glyphosate, a nonselective herbicide which normally cannot be applied over crops without severe crop injury. Research has not demonstrated better weed control in BXN or Roundup Ready cotton than that which can usually be obtained in nontransgenic cotton with traditional weed control systems. However, both transgenic cottons expand the options for weed management and make the mechanics of weed control much easier, less expensive and more convenient. The highest rates of adoption of BXN cotton have been in the states of Arkansas, Tennessee, and Missouri where morningglories are a significant problem and where sicklepod is not prevalent. The Roundup Ready system has been widely adopted as Roundup has a broad spectrum of activity, which includes most of the major annual and perennial grass and broadleaf weeds infesting cotton fields.

US cotton acreage planted with Roundup Ready varieties increased steadily following its introduction in 1997 reaching 70% of planted acreage in 2001. Numerous press articles have reported that cotton growers have adopted the transgenic cultivars as a way to significantly reduce their production costs. Growers have reported making fewer trips across fields applying herbicides, making fewer cultivation trips, and making fewer applications of herbicides. USDA surveys of herbicide usage by cotton growers show a general decline in overall herbicide active ingredient used per acre for most states since 1996/1997 to 2000. Extension Service cotton weed control specialists were surveyed to estimate the changes in tillage, herbicide application trips and handweeding that has occurred on the acreage planted to transgenic cotton. All states reported fewer tillage trips and less handweeding, while herbicide application trips were either reported as unchanged or reduced.

Impacts of Herbicide Tolerant Transgenic Cotton
Change in Pesticide Use: 6.2 millon lbs/yr. decrease in herbicide active ingredients Change in Production Costs: $133 million/yr. Savings in weed control costs.

Contacts:
John Byrd, Mississippi State University 662-325-4537
Email: jbyrd@weedscience.msstate.edu

Ron Vargas, University of California 559-675-7879
Email: rnvargas@ucdavis.edu

Full Report: The Potential for Biotechnology to Improve Crop Pest Management in the U. S.:40 Case Studies by Leonard P. Gianessi, Cressida S. Silvers, Sujatha Sankula and Janet Carpenter National Center for Food and Agricultural Policy, June 2002.