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dc.contributor.authorJeffries, Colin Johnen
dc.date.accessioned2018-01-31T11:46:02Z
dc.date.available2018-01-31T11:46:02Z
dc.date.issued1979
dc.identifier.urihttp://hdl.handle.net/1842/28301
dc.description.abstracten
dc.description.abstractA new selective medium containing pentachloronitrobenzene and 2-ami nobutane - the PAB medium - was developed for use with the soi1-di1ution plate method for the enumeration of fungal propagules of F. solccni var. coeruleum and F. sulphureum in field soil. These fungi cause a dry rotting of potatoes in storage. The efficiency of the PAB medium in the measurement of levels of soil contamination was compared with that of other methods. Also described is the PM70 medium, suitable for the isolation of a number of pathogens, including P. exigua var. foveata from diseased tuber tissue.en
dc.description.abstractThe incidence of dry rot after grading was related logarithmically to the number of F. solccni var. coeruleum propagules in progeny tubersphere soil. Highest levels of progeny tuber contamination with F. solccni var. coeruleum were associated with the planting of infected seed. Planting of contaminated seed sometimes gave high levels of transmission, possibly because dry rot developed after planting. Propagule production by infected seed varied between seasons and may be related to soil temperature. Tuber factors, eg variety and seed size, also influenced propagule production. Of the seed treatments tested, only thiabendazole reduced consistently the transmission of F. solccni var. coeruleum.en
dc.description.abstractLevels of soil contamination increased during the growing season but removal of the seed tuber prevented further increase. Highest numbers of propagules were in a 5 cm diam. zone of soil surrounding the seed and spread of propagules was mainly lateral and downwards forming a decreasing gradient of inoculum with increasing distance from the seed tuber. Propagule distribution on progeny tubers followed the same pattern but harvesting by elevator digger disturbed the soil inoculum, making all progeny tubers highly contaminateden
dc.description.abstractF. solani var. coeruleum survived a 6 year rotation in field soil and this soil-borne inoculum is possibly important in the re-contamination of clean seed stocks.en
dc.description.abstractMost varieties, of those tested, were resistant to infection by F. solani var. coeruleum in November but susceptible by February. Tubers were more susceptible if incubated initially at 4°C rather than at 15°C.en
dc.description.abstractTransmission of F. solani var. coeruleum was compared with that of F. sulphureum. Propagules of F. solani var. coeruleum were produced in cavities in the tuber and in pustules on the tuber surface but F. sulphureum showed little surface sporulation. Thus thiabendazole, which inhibits surface sporulation was inconsistent in reducing transmission of F. sulphureum. Moreover, F. sulphureum sporulated on stems growing from infected seed tubers in the field.en
dc.description.abstractF. sulphureum infected seed usually produced less inoculum than did F. solani var. coeruleum but in one season the reverse was true and was possibly related to high soil temperatures. F. sulphureum does not appear to survive in field soil as well as F. solani var. coeruleum. Although F. sulphureum seems less well adapted than F. solani var. coeruleum for propagule transmission none of the varieties tested was resistant to infection by F. sulphureum.en
dc.publisherThe University of Edinburghen
dc.relation.ispartofAnnexe Thesis Digitisation Project 2017 Block 16en
dc.relation.isreferencedbyAlready catalogueden
dc.titleTransmission studies on the potato pathogens Fusarium solani var. Coeruleum and Fusarium sulphureumen
dc.typeThesis or Dissertationen
dc.type.qualificationlevelen
dc.type.qualificationnamePhD Doctor of Philosophyen


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