Field experiments were conducted at three Virginia locations in 1990 and 1991 to evaluate the effects of cover crop suppression method, nonselective herbicide, no-till cultivation, and herbicide banding on weed control, corn vigor, and corn yield. These factors were evaluated in experimental areas containing either a rye (Secale cereale) cover crop or in areas with no cover crop. In areas with a rye cover crop, the cover crop suppression methods evaluated were paraquat or mechanical suppression via mowing. In areas without a cover crop, paraquat was compared to a treatment without paraquat. Five selective herbicide treatments were evaluated within each level of the variable described above. These treatments included a control or no selective herbicides, a preemergence herbicide combination of atrazine plus metolachlor, and a postemergence herbicide combination of dicamba plus nicosulfuron. The preemergence and postemergence herbicides were applied either broadcast or banded over the crop row. The use of no-till, interrow cultivation was evaluated for each combination of the cover crop suppression method or nonselective herbicide and selective herbicide variables.
Where a rye cover crop was present, paraquat significantly improved control of this species relative to mowing, and it provided significantly better control of most weed species and increased corn vigor and yield. In the absence of a cover crop, paraquat significantly improved weed control, but its effect on corn vigor and yield was dependent on weed pressure. Where weed pressure was moderate to heavy, paraquat significantly improved corn vigor and yield, whereas, it did not have a significant effect on these variables if weed pressure was low. In some situations, paraquat did not significantly improve late season weed control with broadcast selective herbicides, however, it provided quicker control of established weeds which significantly improved corn growth, especially in dry soil conditions.
With or without a rye cover crop, cultivation did not significantly improve weed control, corn vigor, or corn yield when used with broadcast selective herbicides. Banded selective herbicides with cultivation provided weed control and corn vigor and growth equivalent to broadcast selective herbicides without cultivation if weed pressure was low. Where weed pressure is moderate to heavy, banded herbicides with cultivation did not perform as well as broadcast treatments without cultivation. Postemergence herbicides provided weed control and corn growth equivalent to preemergence herbicides, but use of effective nonselective herbicides at planting to control established weeds was critical. / Master of Science
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/46293 |
| Date | 17 December 2008 |
| Creators | VanLieshout, Lawrence Anthony |
| Contributors | Weed Science |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Thesis, Text |
| Format | xii, 142 leaves, BTD, application/pdf, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
| Relation | OCLC# 26064256, LD5655.V855_1992.V364.pdf |
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