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The biology of Geosmithia morbida and susceptibility of walnut and hickory species to thousand cankers disease

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dc.contributor.authorUtley, Curtis, author
dc.contributor.authorTisserat, Ned, advisor
dc.contributor.authorCranshaw, Whitney, advisor
dc.contributor.authorJacobi, William, committee member
dc.contributor.authorKlett, James, committee member
dc.date.accessioned2007-01-03T05:34:05Z
dc.date.available2007-01-03T05:34:05Z
dc.date.issued2013
dc.description.abstractSince 2001 widespread mortality of black walnut (Juglans nigra) has been reported in Colorado, USA. Affected trees initially show a yellowing and thinning of leaves in the upper crown, followed by twig and branch dieback and ultimately tree death. We report that this mortality is the result of a combination of an expanded geographic range of the walnut twig beetle (Pityophthorus juglandis), its aggressive feeding behavior on black walnut, and extensive cankering caused by a filamentous ascomycete in the genus Geosmithia (Ascomycota: Hypocreales). Thirty seven Geosmithia strains collected from J. californica, J. hindsii, J. major, and J. nigra in eight USA states (AZ, CA, CO, ID, OR, UT, WA) were compared using morphological and molecular methods (ITS rDNA sequences). Strains had common characteristics including a yellowish color of conidia en masse, growth at 37°C, and absence of growth on Czapek-Dox agar and belonged to a single species described here as G. morbida. G. morbida is the first Geosmithia species documented as a plant pathogen. We also tested the susceptibility of hickory and walnut species to G. morbida in greenhouse and field studies. Carya illinoinensis, C. aquatica, and C. ovata were immune. All walnut species tested, including J. ailantifolia, J. californica, J. cinerea, J. hindsii, J. major, J. mandshurica, J. microcarpa, J. nigra and J. regia developed cankers following inoculation with G. morbida. J. nigra had the largest cankers, whereas J. major, a native host of the WTB and presumably G. morbida, had smaller and more superficial cankers. Canker size differed among maternal half-sibling families of J. nigra and J. cinerea, indicating genetic variability in resistance to G. morbida. Our inoculation studies with G. morbida have corroborated many of the field observations on susceptibility of hickory and walnut species to TCD, although the ability of the WTB to successfully attack and breed in walnuts is also an important component in TCD resistance.
dc.format.mediumborn digital
dc.format.mediummasters theses
dc.identifierUtley_colostate_0053N_11628.pdf
dc.identifier.urihttp://hdl.handle.net/10217/79196
dc.languageEnglish
dc.language.isoeng
dc.publisherColorado State University. Libraries
dc.relation.ispartof2000-2019
dc.rightsCopyright and other restrictions may apply. User is responsible for compliance with all applicable laws. For information about copyright law, please see https://libguides.colostate.edu/copyright.
dc.subjectblack walnut
dc.subjectGeosmithia morbida
dc.subjectthousand cankers disease
dc.subjectwalnut twig beetle
dc.subjectCarya
dc.subjectJuglans
dc.titleThe biology of Geosmithia morbida and susceptibility of walnut and hickory species to thousand cankers disease
dc.typeText
dcterms.rights.dplaThis Item is protected by copyright and/or related rights (https://rightsstatements.org/vocab/InC/1.0/). You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).
thesis.degree.disciplineBioagricultural Sciences and Pest Management
thesis.degree.grantorColorado State University
thesis.degree.levelMasters
thesis.degree.nameMaster of Science (M.S.)

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