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Comparative epidemiology of Phytophthora diseases of Rhododendron

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dc.contributor.advisor Grunwald, Niklaus J.
dc.creator Taylor, Clare Rebecca
dc.date.accessioned 2011-07-06T21:18:22Z
dc.date.available 2011-07-06T21:18:22Z
dc.date.copyright 2011-06-03
dc.date.issued 2011-07-06
dc.identifier.uri http://hdl.handle.net/1957/21936
dc.description Graduation date: 2012 en_US
dc.description.abstract Rhododendron species are host to many Phytophthora species and are an important crop in the nursery industry. The foliar epidemiology of twelve Phytophthora diseases on Rhododendron was studied in field and growth chamber experiments on two Rhododendron cultivars. The relative aggressiveness of Phytophthora spp. was assessed using disease incidence, severity, and sporulation. Plant experiments were conducted on whole plants and on detached leaves. Growth rates of lesions and colonies for each species at different temperatures were determined in growth chambers on detached leaves and in agar culture. Whole plants were inoculated in the field in four experiments conducted at three to four month intervals. The twelve species studied appeared to fall into two groups with P. citrophthora, P. foliorum, P. kernoviae, P. parasitica, P. plurivora and P. ramorum being the most aggressive species; sporulating the most, developing the largest lesions or exhibiting the highest infection rate. P. cactorum, P. cambivora, P. cinnamomi, P. lateralis, P. nemorosa and P. syringae were less aggressive on foliage under most conditions, with the exception of P. syringae which developed the largest lesions at lower temperatures typical of spring time in temperate climates. It is apparent that different Phytophthora species are more active at different temperatures and thus surveys for Phytophthora infections should be concerned about different species at different times of the year. P. kernoviae is not known to be present in the US. P. kernoviae is of particular concern due to the high sporulation levels observed in detached leaf and whole plant inoculations. Rhododendron spp. appear to be likely candidate vectors for the introduction of novel Phytophthora pathogens. This work has implications for the management of Phytophthora pathogens and importation or movement of Rhododendron plants across nurseries. en_US
dc.language.iso en_US en_US
dc.subject Phytophthora en_US
dc.subject Rhododendron en_US
dc.subject Epidemiology en_US
dc.subject Plant pathology en_US
dc.subject Temperature en_US
dc.subject.lcsh Rhododendrons -- Diseases and pests en_US
dc.subject.lcsh Phytophthora diseases en_US
dc.subject.lcsh Phytophthora en_US
dc.title Comparative epidemiology of Phytophthora diseases of Rhododendron en_US
dc.type Thesis/Dissertation en_US
dc.degree.name Master of Science (M.S.) in Botany and Plant Pathology en_US
dc.degree.level Master's en_US
dc.degree.discipline Science en_US
dc.degree.grantor Oregon State University en_US
dc.contributor.committeemember Mahaffee, Walt
dc.contributor.committeemember Mundt, Chris
dc.contributor.committeemember Hansen, Everett


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