GMOs and the Changing Use of Pesticides

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GMOs and the Changing Use of Pesticides

• Chris Boerboom
• Extension Weed Scientist
• University of Wisconsin - Madison

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Herbicide Resistant Crops (HRC) The concept
CP4 EPSPS Roundup gene Ready

• Soybeans Roundup Ready
• Corn Roundup Ready, Liberty Link
• Cotton BXN, Roundup Ready
• Canola Liberty Link, Roundup Ready

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Audience Survey

• FACT
• Herbicide resistant crops are fully resistant
  (no injury) to a specific herbicide such as
  Roundup
• QUESTION
• Will farmers spray more herbicide if they use
  this technology?

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Public Perception

• Biotech Critics
• Herbicide resistant crops are resistant to
  herbicides so farmers will be spraying more
  herbicide, increasing food and environmental
  hazards
• Charles Benbrooks study on Roundup Ready
  soybeans shows that the amount of herbicide used
  on these beans is two to five times the amount of
  spraying for conventional beans.
• National Family Farm Coalition

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Herbicide Use in HRC

• Biotech Advocates respond
• These biotech crops provide solutions for pest
  and weed control that can have added benefits .
  . . including a reduction in the number of
  pesticide sprays and reduced environmental
  exposure, reduced labor, higher yields,
  compatibility with more sustainable agricultural
  practices, . . .
• Monsanto

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Roundup Ready Soybeans
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Soybean Herbicide Use Patterns(Major States)
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Soybean Herbicide Rates (Major States)
3 increase with RR soybeans (Lin et al.
2001) 13 increase with RR soybeans (Benbrook
2001)
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What do pounds of herbicide mean?

• Herbicide programs in
• Conventional Soybeans
• Raptor at 5 oz/a
• 0.04 lb/a imazamox
• Pursuit Plus at 2.5 pt/a
• Prowl at 1 pt/a
• 1.25 lb pendimethalin
• 0.06 lb imazethapyr
• 1.31 lbs total

• Standard herbicide program Roundup Ready Soybeans
• Roundup UltraMAX at 26 oz/a
• 0.75 lb glyphosate

Should it be a question of the number of
ingredients applied and their toxicity? Conventio
nal 2.8 ai/ acre Roundup Ready 1.4 ai/acre
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Roundup Ready Soybeans in Conservation Tillage
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Herbicide Resistant Corn
US Adoption in 2002 only 10 (LL RR) 24 less
herbicide applied in 2000 vs 1991
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Effects of Herbicide Resistant Crops on Pesticide
Use

• Large shift to glyphosate (Roundup) use in
  soybeans
• Increase in total pounds of herbicide applied
• Fewer herbicide ingredients and applications per
  field
• Minor effect in corn to date

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Effect of Herbicide Resistant Crops on Pesticide
Use

• So what?
• Debate has not evaluated toxic effects on
  applicators, food, or environment
• Technology has lowered the cost soybean weed
  management (216M in 1999) and stifled new
  research
• May further the adoption of conservation tillage
• Herbicide resistant weeds are a concern

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Will herbicide resistance threaten the success of
HRCs?

• Wisconsin ALS herbicide use in 1996
• Soybeans Corn
• Pursuit 66 Permit 4
• Pinnacle 47 Accent 22
• Beacon 3
• Python 4
• Current ALS resistant weeds in Wisconsin
• giant foxtail, green foxtail, eastern black
  nightshade, shattercane, common ragweed, giant
  ragweed, kochia, waterhemp

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Will herbicide resistance threaten the success of
HRCs?

• Current weed species with glyphosate resistance
  in the world
• rigid ryegrass and Italian ryegrass
• goosegrass
• horseweed (30 of TNs cotton infested)

Solution Another herbicide will be applied or
tank mixed with glyphosate Consequence Added
cost and perhaps an added application, potential
injury, which erode the benefits of the
technology
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Bt Crops for Insect Resistance

• Bt Bacillus thuringiensis, a natural soil
  bacteria
• produces a protein that is toxic to caterpillars
• Bt Corn European
• Corn Borer resistance
• Bt Cotton tobacco budworm, cotton bollworm,
  and pink bollworm resistance

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Bt Crops Perceptions

• Biotech Critic
• In essence, the plants are insecticides.
• Green Peace
• Biotech Advocate
• Fewer pesticides will be sprayed and crop yields
  will be higher.
• Cant directly state that Bt crops will replace
  toxic pesticides

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Bt Corn Adoption
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Effect of Bt Corn on Insecticide Use

• EPA Because many farmers do not use
  insecticides to control European corn borer,
  large changes in insecticide use are not
  expected.
• Estimates
• EPA 3.9 million fewer acres treated
• Benbrook increase from 4 in 1995 to 5 in 2000
• Carpenter 1.5 decrease from 1995 to 1999

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Potential Effect of Bt Corn

• Bt Corn for Corn Rootworm Control
• In the US
• 9.0 million lb insecticide applied in 2001
• Lorsban and Counter were 68 of total pounds
  applied
• In Wisconsin
• Regent and Force applied to 11 of corn acres
• (16 of corn acres treated with insecticides)

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Conclusions Pesticide use

• Effect of herbicide resistant crops on pesticide
  use
• - rate debate is relatively inconsequential
• - toxicity and resistance are of greater concern
• Effect of Bt crops on pesticide use
• - acres treated is important applicator, food,
  and environmental issues
• Effect of genetically engineered crops on
  pesticide use is a relatively minor point
  relative to other social/political issues.

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References

• Carpenter, J. E. and L. P. Gianessi. 2001.
  Agricultural biotechnology Updated benefit
  estimates. National Center for Food
  Agricultural Policy. www.ncfap.org/reports/biotech
  /updatedbenefits.pdf
• Fernandez-Cornejo, J. and W. D. McBride. 2002.
  Genetically engineered crops U.S. adoption and
  impacts. ERS Agricultural Economic Report No.
  AER810. www.ers.usda.gov/publications/aer810/
• Carpenter, J., A. Felsot, T. Goode, M. Hammig, D.
  Onstad, and S. Sankula. 2002. Comparative
  environmental impacts of biotechnology-derived
  and traditional soybean, corn, and cotton crops.
  Council for Agricultural Science Technology.
  www.cast-science.org/biotechnology/index.html
• Benbrook, C. M. 2001. Troubled times amid
  commercial success for Roundup Ready soybeans.
  Northwest Science and Environmental Policy
  Center. www.biotech-info.net/troubledtimes.html
• NASS/USDA. 2002. Agricultural chemical usage 2001
  field crops summary. http//usda.mannlib.cornell.e
  du/reports/nassr/other/pcu-bb/agcs0502.pdf