Goplen, Jared2015-10-132015-10-132015-07https://hdl.handle.net/11299/174767University of Minnesota M.S. thesis. July 2015. Major: Applied Plant Sciences. Advisors: Jeffrey Gunsolus, Craig Sheaffer. 1 computer file (PDF); v, 68 pages.As herbicide-resistant weed populations become increasingly problematic in crop production, alternative strategies of weed control are necessary. Ambrosia trifida, one of the most competitive agricultural weeds in row crops, has developed resistance to multiple herbicide biochemical sites of action within the plant, necessitating the development of new and integrated methods of weed control. This research indicates that various crop rotations are more conducive to giant ragweed emergence than others, and that long term giant ragweed management can be accomplished by implementing a zero weed threshold to deplete the weed seed bank. Giant ragweed also retains seed well into the harvest season, indicating that there is ample time to remove escaped giant ragweed from production fields prior to seed shattering to limit replenishment of the weed seed bank. Ultimately, these results indicate that there is potential to manage Ambrosia trifida by eliminating seed bank inputs and degrading the weed seed bank.enCrop rotationHarvest weed seed controlherbicide resistanceseed bank depletionseedling emergenceSeed RetentionThesis or Dissertation