Use of digital image analysis to identify Rhizoctonia solani and Rhizoctonia zeae resistance in Festuca arundinacea plant introductions

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dc.contributor.authorSykes, Virginia Roseannaen
dc.contributor.committeechairHorvath, Brandon J.en
dc.contributor.committeememberAskew, Shawn D.en
dc.contributor.committeememberBaudoin, Antonius B.en
dc.contributor.committeememberGoatley, J. Michael Jr.en
dc.contributor.departmentPlant Pathology, Physiology, and Weed Scienceen
dc.date.accessioned2014-03-14T21:36:31Zen
dc.date.adate2009-06-10en
dc.date.available2014-03-14T21:36:31Zen
dc.date.issued2009-04-22en
dc.date.rdate2009-06-10en
dc.date.sdate2009-05-21en
dc.description.abstractBrown patch, caused by <i>Rhizoctonia solani</i> Kuhn, is an important disease on tall fescue (TF, <i>Festuca arundinacea</i> Schreb, synonym <i>Schedonorus phoenix</i> (Scop.) Holub). <i>Rhizoctonia zeae</i> Voorhees, a related pathogen, causes similar symptoms. Confusion over which <i>Rhizoctonia</i> species is causing symptoms and subjective visual evaluations of disease severity may contribute to variability in observed BP resistance of TF cultivars at multiple locations. The objectives of this study were to develop an objective digital image analysis (DIA) method for evaluating disease and to use DIA to screen tall fescue plant introductions (PIs) for resistance to <i>R. solani</i> and <i>R. zeae</i>. There was a strong correlation (r<sup>2</sup> = 0.97) between actual disease severity, measured by applying lesioned tissue of a known area to healthy leaves, and DIA calculated disease severity using scanned images of individual leaves (DIA-IL). The accuracy and precision of visual evaluations and DIA evaluations of entire plants (DIA-WP) were evaluated using DIA-IL as a standard of accuracy. Accuracy of DIA-WP was not significantly different from visual evaluation accuracy. Precision was significantly higher for DIA-WP. Evaluation of PIs and putatively BP resistant TF cultivars for resistance to <i>R. solani</i> and <i>R. zeae</i> using DIA-WP identified clones within each PI that ranked high for resistance to <i>R. solani</i> or <i>R. zeae</i>. No clones were identified with high resistance to both <i>R. solani</i> and <i>R. zeae</i>. Improved precision of DIA evaluation methods and inclusion of <i>R. zeae</i> in BP resistance breeding may decrease variability of TF cultivar performance across locations.en
dc.description.degreeMaster of Scienceen
dc.identifier.otheretd-05212009-201102en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-05212009-201102/en
dc.identifier.urihttp://hdl.handle.net/10919/42769en
dc.publisherVirginia Techen
dc.relation.haspartVRSYKESthesis.pdfen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectturfgrassen
dc.subjectdisease evaluationen
dc.subjecttall fescueen
dc.subjectbrown patchen
dc.subjectSchedonorus phoenixen
dc.titleUse of digital image analysis to identify <i>Rhizoctonia solani</i> and <i>Rhizoctonia zeae</i> resistance in <i>Festuca arundinacea</i> plant introductionsen
dc.typeThesisen
thesis.degree.disciplinePlant Pathology, Physiology, and Weed Scienceen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.levelmastersen
thesis.degree.nameMaster of Scienceen

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