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Title: SEEDBANK PERSISTENCE OF A DECLINING GIANT RAGWEED POPULATION: INITIAL RESULTS OF A LONG-TERM STUDY

Author
item NORDBY, DAWN - UNIV OF ILLINOIS
item Williams, Martin
item Chee Sanford, Joanne

Submitted to: Weed Science Society of America Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 11/5/2004
Publication Date: 2/7/2005
Citation: Nordby, D.E., Williams, M.M., Chee-Sandford, J.C. 2005. Seedbank persistence of a declining giant ragweed population: Initial results of a long-term study[abstract]. Weed Science Society of America Meeting. Vol. 45:63.

Interpretive Summary:

Technical Abstract: A long-term study of giant ragweed (Ambrosia trifid) seedbank persistence was initiated in spring of 2002 at the Northern Illinois Agronomy Research Center near Dekalb. The study system is managed to prohibit seedbank additions, therefore focusing on seedbank losses from an initial giant ragweed population. The effects of two tillage types, conventional and no-till, are tested in both crops of a corn/soybean rotation. At the onset of the study and each succeeding fall, soil samples are collected and analyzed to determine seedbank density at depth increments of 0 to 2 cm, 2 to 6 cm, 6 to 12 cm, and 12 to 20 cm. Seedbank losses due to emergence are also monitored weekly from early April through August every year. While tillage has had no effect on total giant ragweed emergence to date, seedbank losses from emergence have been lower in soybeans compared to corn since inception. Conventional tillage had no effect on vertical distribution of giant ragweed seedbank in 2002, however by 2003, seedbank density was significantly lower in the 0 to 2cm depth in the tilled treatment compared to the other depths in the same treatment. No differences in vertical seedbank distribution in the no-till treatments were detected by fall of 2003, although 2004 data will be presented. Giant ragweed seedbank persistence will continue to be studied through at least 2008. Long-term evaluation of this project will increase our understanding of giant ragweed seedbank ecology and provide a study system for exploring the role of microbially-mediated seed decay.