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EPA IRM Update for Bt (Bacillus thuringiensis) Cotton Plant-Incorporated Protectants

Sharlene R. Matten


The United States Environmental Protection Agency (EPA) mandates insect resistance management (IRM) programs for Bollgard® (Cry1Ac) cotton (see EPA, 2001; Matten and Reynolds, 2003b) and Bollgard® II cotton (Cry2Ab2 and Cry1Ac) plant-incorporated protectants (PIPs) (Matten and Reynolds, 2003a). There are three structured refuge options with specific deployment requirements:

  • 5% external, unsprayed refuge: >150 ft. wide (>300ft. preferred), <1/2 mile (1/4 mile or adjacent preferred);
  • 20% external, sprayed refuge: <1 mile (1/2 mile or closer preferred);
  • 5% embedded refuge: >150 ft. wide (>300ft. preferred), refuge can only be treated if entire field treated;
  • 5% in-field refuge for PBW: refuge must be at least 1 non-Bt cotton row for every 6-10 rows of Bt cotton; and
  • Community refuge: use either 5% external, unsprayed and/or 20% external, sprayed refuge.

Other requirements are: annual resistance monitoring program, remedial action plans, grower education, compliance assurance program, research, and annual reporting. The registration for Bollgard® cotton (EPA Registration Number 524-478) expires September 30, 2006, except for the 5% external, unsprayed refuge option which expires September 30, 2004. EPA intends to review the data specified in the data requirements concerning alternate hosts and chemical insecticide sprays on Bt cotton, and decide in 2004 whether the new data support continuation of the 5% external, unsprayed refuge. If these data support the continued availability of the 5% external, unsprayed refuge option, EPA may approve an amendment to this registration to maintain the availability of this option.

The registration for Bollgard® II cotton (EPA Reg. No. 524-522) was granted on December 23, 2002 and expires May 1, 2004 due to the expiration of the temporary tolerance exemption for the Cry2Ab2 protein.

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Document last modified 04/27/04