Project Number: 6402-22000-042-00
Project Type: Appropriated

Start Date: May 17, 2005
End Date: May 16, 2010

Objective:
Assess biological and ecological characteristics of weeds that contribute to their invasive and adaptive potential in an effort to provide more effective weed control tactics. Determine specific morphological and physiological characteristics of herbicide-resistant weed biotypes (e.g., horseweed), and invasive (e.g., cogongrass), native and non-native (e.g., pitted morningglory, purple nutsedge, johnsongrass) weed species and causes for their variable control with herbicides. Develop and/or refine effective, economical, environmentally safe, and sustainable weed management systems for cotton, soybean, and corn by integrating chemical, cultural, and herbicide-resistant cultivars with a greater emphasis on conservation tillage practices. Determine ecological changes that occur in the weed populations as a consequence of cultural practices and herbicide changes, including weed species shifts, changes in seed bank dynamics, and the development of herbicide resistance. Investigate mechanism of resistance in glyphosate-resistant horseweed. Assess risks associated with glyphosate-resistant cropping systems on soil microbial ecology, soybean diseases, and nitrogen fixation/assimilation.

Approach:
Sustainable integrated weed management systems will be developed by integrating chemical, cultural, and mechanical control methods to exploit the benefits of each practice to minimize herbicide inputs and to maximize weed control and yield. Focus will be on use of conservation tillage, cover crops, crop rotation, narrow row spacing, competitive cultivars, and herbicide-resistant crops to reduce herbicide use and risks. Research will evaluate changes in the distribution and type of weed species and seed bank dynamics as a consequence of changes in production practices, such as herbicide-resistant crops, cover crops, row spacing, and conservation tillage. A broad range of techniques will used to assess biology and management of weed species and impact of herbicide-resistant cropping systems on weed populations and species shifts and resistance. Investigations will include biological and ecological aspects of a number of pernicious, noxious, and invasive weeds to understand the traits that lead to weediness and devise effective control measures.