Bitter rot, caused by the fungus <i>Greeneria uvicola</i> (Berk. & Curtis) Punith., is one of the most important fruit rot diseases that threaten the burgeoning winegrape (<i>Vitis vinifera</i> L.) industry in the southeastern United States. Epidemiological studies were conducted to examine the variation in aggressiveness among isolates, period of fruit susceptibility in <i>V. vinifera</i>, relative susceptibility of cultivars to bitter rot, and influence of temperature and duration of wetness on infection. Detached <i>V. vinifera</i> ?Chardonnay? fruit were inoculated with 10 isolates of <i>G. uvicola</i> obtained from fruit of <i>V. vinifera</i>, <i>V. rotundifolia</i> (muscadine grape), and a French-American hybrid. Isolates HCMD1 and HCMD5, obtained from <i>V. vinifera</i> grapes from a Maryland vineyard, were the most aggressive. Severity of disease on fruit inoculated with isolates collected from <i>V. vinifera</i> was significantly higher than with isolates collected from <i>V. rotundifolia</i>. The period of fruit susceptibility was distinguished by inoculating intact clusters of grapes in vineyards in Alamance Co. and Rockingham Co., NC, every 2 weeks from bloom until 2 weeks before harvest. Susceptibility of <i>V. vinifera</i> ?Merlot,? ?Chardonnay,? and ?Cabernet Franc? fruit increased from bloom until véraison in 2003 and from bloom until 2 weeks before véraison in 2004. The relative susceptibility of 38 cultivars and selections, including 23 <i>V. vinifera</i> cultivars and 5 French-American hybrids, was determined by inoculating and incubating detached fruit at 26°C. Fruit of <i>V. vinifera</i> were significantly more susceptible to infection by <i>G. uvicola</i> than French-American hybrids. <i>V. vinifera</i> ?Petite Sirah,? ?JB97-8-0-7,? ?MissBlanc,? ?Roussanne,? ?Mourvédre,? and ?Petit Verdot? were among the most susceptible to the bitter rot pathogen. <i>V. aestivalis</i> ?Cynthiana Norton,? <i>V. vinifera</i> ?Arkansas 1271? and ?Riesling,? and French-American hybrid ?Traminette? and ?Chardonel? were among the most resistant. Growth chamber studies also were conducted to examine the influence of temperature and duration of wetness on infection. Detached fruit of <i>V. vinifera</i> ?Cabernet Sauvignon,? ?Cabernet Franc,? and ?Chardonnay? were inoculated and incubated at 14, 18, 22, 26, or 30°C for 6, 12, 18, or 24 hours. The optimal conditions for infection of fruit by <i>G. uvicola</i> were a temperature of 23.7°C and 9 hours of wetness.
| Identifer | oai:union.ndltd.org:NCSU/oai:NCSU:etd-12162004-150249 |
| Date | 16 December 2004 |
| Creators | Miranda, Julie Guerra |
| Contributors | Turner Bond Sutton, Barbara B. Shew, Frank J. Louws |
| 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-12162004-150249/ |
| 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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