| Title |
Investigators | Department | Objectives | Approach Keywords | Progress Reports | Impact Statements | Publications | |
Project * COL00221A(See Project History for COL00221) | |
| Title | Characterize Weed Population Dynamics for Improved Long-Term Weed Management Decision Making |
| Investigator(s) | Westra, P; |
| Department | Bioagricultural Sciences and Pest Mgmt. |
| Objectives | 1. Quantify the demography of giant ragweed (Ambrosia trifida L.) and common sunflower (Helianthus annuus L.) across the North Central region and use this information to enhance weed management decision support systems. 1a. Compare the relative importance of spatial variation in demographic rates at different levels of scale to inter-annual variation within sites. 1b. Examine soil feedback mechanisms as they relate to variation in species demography. 1c. Partition nutrient and water stress in common sunflower and giant ragweed plants alone and in combination with crops. 2. Incorporate weed demographic information into a WeedSOFT module that quantitatively accounts for the economic losses of weed escapes and explore the significance of escapes with a risk-based approach. |
| Approach | Field level replicated biology research will be utilized to address the objectives of this project. Greenhouse and laboratory studies will be utilized as needed to support the research objectives. Data collected will be analyzed utilizing appropriate statistical techniques such that the results of this research can be published in peer reviewed journals. Research will be conducted at the Colorado State University ARDEC research facility near Fort Collins, CO. The results of this research will be shared with growers and clients in Colorado. |
| Keywords | weed biology, weed science, plant ecology, bioeconomic models, crop and weed competition, weed spatial dynamics |
| Progress Reports | |
| 2006 | The ninth year of research of a 10 year weed shift study evaluating the utility of Roundup Ready crop technology for weed management has shown that over a multiple-year timeframe, excessive reliance on a single weed management strategy tends to slowly enrich the weed population with those species that may be inherently more difficult to control with that strategy. When only glyphosate is used for weed control in Roundup Ready crops, there is a slow increase in weeds such as common lambsquarter, wild buckwheat, and toothed spurge. Grasses and broadleaf weeds (including kochia) in this study continue to be well controlled. By incorporating a reduced rate of soil applied herbicides into the system, weed populations were reduced even further. There was a positive corn yield response where a soil applied herbicide program was put down prior to post-emergence applications of glyphosate. Conventional herbicide treatments failed to provide adequate weed control in 2006, and as a result, such treatments resulted in reduced corn yields. Studies on herbicide resistant weeds were conducted with kochia and with Palmer amaranth to evaluate the genetics and molecular biology of dicamba and glyphosate resistance in these weeds respectively. |
| Impact | |
| 2006 | As America moves to the production of more biofuels, it will become increasingly important to devise cost-effective weed management practices that maximize corn yields with minimal environmental impacts. This research helps address potential threats to sustainable corn production in Colorado, and should help maximize corn yields when limited irrigation is used to produce corn. This research will help maintain the sustainability of reduced till crop production in Colorado. |
| Publications | |
| 2006 |
Shaner, D. L., G. Brunk, D. Belles, P. Westra, S. Nissen. 2006. Soil dissipation and biological activity of metolachlor and S-metolachlor in five soils. Pest Manag. Sci. 62:617-623. Shaner, D. L., P Westra, and S. Nissen. 2006. AMADS Increases the Efficacy of Glyphosate Formulations on Corn. Weed Technology. 20:179-183. |