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An IPM Program for the Environmentally and Economically Sustainable Control of Glyphosate-Resistant Palmer Amaranth in Conservation Tillage Cotton

2011 Grantee: University of Georgia
Funding Awarded: $109,115
Fact Sheet PDF (2 pp, 560k, about PDF)


The widespread use of the herbicide glyphosate has resulted in the development of glyphosate-resistant weeds, specifically, glyphosate-resistant (GR) Palmer amaranth. This pest infests more than 2 million hectares in 10 states, which is approximately 50 percent of the total acreage devoted to upland cotton production in the US.

The immediate goal of this project is to develop an integrated management (IPM) program which combines two strategies to control GR Palmer amaranth: the use of heavy-residue cover-crops and “banded” herbicide applications. Currently, growers throughout the Southeastern US rely on tillage, cultivation, and up to six herbicide applications per year to manage Palmer amaranth. Herbicides can cost growers in the state of Georgia alone upwards of $100 million. The implementation of an IPM program to reduce pesticide applications will result in more sustainable cotton farming.

This project is led by the University of Georgia, in collaboration with the University of Georgia Extension Service, and growers in Georgia, Alabama, South Carolina, North Carolina, Mississippi, and Tennessee.


  • Develop an integrated cotton weed pest management system, using cover crops and herbicide banding techniques, for the control of glyphosate-resistant Palmer amaranth in conservation tillage
  • Facilitate the return to conservation tillage and the adoption of cover crops Improve glyphosate-resistant Palmer amaranth control in conservation tillage cotton using cover crops while reducing herbicide inputs and preserving yield
  • Improve the environmental profile of Georgia farms and adjacent habitats
  • Improve grower economic sustainability


  • Grower-collaborators will assist with the development and implementation of several on-farm experiments that will compare current production and weed management systems with heavy rye production systems with reduced pre– and at-planting herbicide inputs.
  • Demonstrations will transfer results from small-plot trials directly to stakeholders for rapid adoption.
  • Common agricultural data will be collected throughout the season to characterize weed control and yield as affected by cover crop and a reduced input herbicide system.
  • The ecological impacts of rye residue and herbicide application program will be evaluated using a set of environmental metrics.

Knowledge Survey and Transfer

  • A grower survey during the first year of the study will characterize Georgia growers’ cotton producing practices. The survey will identify the crops, herbicides, and mechanical weed control practices that were used before and after the development/confirmation of GR Palmer amaranth. Additional questions will explore the perceived environmental and economic advantages and disadvantages of IPM strategies.
  • A follow-up survey in the second year of the study will evaluate growers’ interest and participation in cover crop production field days and workshops, their current opinions about the benefits of conservation tillage, cover crops, banded herbicide applications, and their likelihood to implement an IPM program.
  • Results from field trials will be made available to local stakeholders in the form of fact sheets distributed at Georgia county extension meetings, that are attended by more than 2,000 growers annually.
  • Grower-collaborators will discuss their experiences with other transitioning farmers at cotton production field days conducted at the demonstration sites.
  • A crop production video demonstrating the production and management of winter cover crops, the techniques for proper planting into a high residue system, and the potential modifications required for adapting existing herbicide sprayers to banded application patterns will be produced and distributed at the same events.
  • The outcomes from research efforts will also be shared with cotton growers and extension personnel in the neighboring states of Alabama, South Carolina, North Carolina, Mississippi, and Tennessee, which are also heavily infested with GR Palmer amaranth.

Desired Outcomes

  • Improve GR Palmer amaranth control in cotton using cover crops while reducing herbicide inputs and preserving yield. Success will be measured by showing that Palmer amaranth densities do not increase in the integrated system and that yields are not adversely affected.
  • Facilitate the return to conservation tillage and the adoption of cover crops. Success will be measured by observing an increase in the number of acres returning to, or estimated to return to, heavy-residue conservation tillage.
  • Improve the environmental profile of Georgia farms and adjacent habitats. Success will be measured by demonstrating a reduction in the number of herbicide sprays, a reduction in the amount of spray applied, and reductions in field Environmental Impact Quotient values with the integrated system.
  • Improve grower economic sustainability. Success will be measured by economic analyses demonstrating that the costs of the integrated systems do not exceed those of growers’ current systems and that yield returns remain the same or increase.

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