<p>Purple and yellow nutsedge are herbaceous perennial weeds that are among the world?s worst pests. Nutsedge species are problematic due to their perennial nature, longevity of tubers, and prolific tuber production. Due to the relatively difficulty in reducing purple and yellow nutsedge populations, herbicide-management programs in cropping systems that target nutsedge species need to be developed. Field studies were conducted to evaluate potential reduction in purple and yellow nutsedge populations using sulfentrazone and glyphosate management programs and site-specific management in a tobacco and soybean rotation, as well as using sulfentrazone, glyphosate, and halosulfuron management programs in a soybean and corn rotation. All weed management systems reduced purple nutsedge densities similarly in the tobacco and soybean rotation. Sulfentrazone plus clomazone preplant incorporated (PPI) in tobacco or preemergence (PRE) in glyphosate-resistant (GR) soybean reduced yellow nutsedge densities 82 and 99%, respectively. Postemergence (POST) treatments of glyphosate in GR soybean did not increase yellow nutsedge reductions when sulfentrazone was applied in tobacco or GR soybean. Glyphosate applied on a site-specific basis POST with a light-activated hooded sprayer (LAS) reduced yellow nutsedge populations as effectively as glyphosate POST broadcast treatments in GR soybean. Weed management systems that included sulfentrazone PRE fb the LAS in GR soybean reduced POST herbicide use by at least 86%, compared to broadcast applications. Sulfentrazone plus clomazone PRE alone in GR soybean followed by (fb) nicosulfuron POST in GR corn reduced purple and yellow nutsedge populations by 48 and 85% relative to the nontreated control, respectively. Clomazone PRE in GR soybean fb sequential treatments of glyphosate POST in GR soybean and in GR corn, reduced purple and yellow nutsedge populations equivalent to soybean PRE herbicide programs and other GR corn POST management programs. Halosulfuron POST treatments reduced yellow nutsedge populations (> 90%) equivalent to glyphosate POST treatments in corn regardless of soybean PRE herbicide program. Greenhouse studies were conducted to evaluate cotton POST herbicides fb MSMA late postemergence (LPOST) for foliar and tuber reduction of yellow and purple nutsedge when applied to nutsedge foliage at two different application timings. CGA-3626222 treatments reduced purple and yellow nutsedge shoot and root/tuber dry weights equivalent to glyphosate POST fb MSMA LPOST. MSMA at 1120 and 2240 g ai/ha and glufosinate POST fb MSMA LPOST reduced purple and yellow nutsedge shoot dry weights, although reduction was greater at smaller nutsedge application heights. Less reduction was obtained with pyrithiobac POST fb MSMA LPOST. The addition of MSMA in mixture to other POST herbicides was of benefit for nutsedge growth reductions with pyrithiobac, but was seldom beneficial with other herbicides. These data initiated studies to evaluate the physiological behavior of CGA-362622 in purple and yellow nutsedge for possible reasons of control. Lab studies were conducted to evaluate absorption, translocation, and metabolism of 14C-CGA-362622 when foliar applied to purple and yellow nutsedge. Less than 53% of the herbicide was absorbed after 96 h. Both nutsedge species translocated appreciable herbicide (30%) out of the treated leaves. Translocation was both acropetal and basipetal, with at least 25% transported basipetally. Neither nutsedge species translocated over 4% of applied radioactivity to the tubers and roots. Most of the metabolites formed by the nutsedge species were more polar than 14C-CGA-362622 and averaged 69 and 61% of the radioactivity in purple and yellow nutsedge. The half-life of CGA-362622 was estimated at 4 h in both purple and yellow nutsedge.<P>
| Identifer | oai:union.ndltd.org:NCSU/oai:NCSU:etd-20020310-225606 |
| Date | 18 March 2002 |
| Creators | Troxler, Shawn Christopher |
| Contributors | Dr. John W. Wilcut, Dr. W. David Smith, Dr. David W. Monks |
| Publisher | NCSU |
| Source Sets | North Carolina State University |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://www.lib.ncsu.edu/theses/available/etd-20020310-225606 |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to NC State University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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