Please read the abstract in the section 00front of this document / Dissertation (Magister Institutiones Agrariae)--University of Pretoria, 2005. / Plant Production and Soil Science / unrestricted

Ethel M. Doidge's thesis is placed on the UIR in 2013 to celebrate 140 years of university education in South Africa. She was the first women to receive a D.Sc. from Unisa'a predecessor, the University of the Cape of Good Hope in 1914 / This thesis researched a mango disease which caused considerable loss to mango growers in South Africa at the beginning of the twentieth century, particularly around Barberton, Warm baths and the coastal region of Natal. The disease caused dark angular spots on the leaves. This did not noticeably affect the general health of the tree, but served as a source of infection for the fruit. The infected fruit is detached from the tree by the slightest air movement and falls rotting to the ground. The infection is carried by wind and rain. Several spraying experiments were carried out at Barberton in an orchard placed at the author's disposal by Messrs Winter Brothers during an exceptionally dry season, which showed that spraying with Bordeaux mixture, iron sulphide or Hyco/ was useless in checking the disease. The disease had not been described in the literature before. According to the author, the cause of the disease was a flagellate bacillus Bacillus mangiferae. It invades the parenchyma, wedging apart and killing the cells and causing gummosis, but it does not touch the lignified tissues. The organism is described, and was tested in detail in laboratory experiments and a resume of its salient characters is given in the thesis / Agriculture and  Animal Health / D.Sc. (Botany)

Ethel M. Doidge's thesis is placed on the UIR in 2013 to celebrate 140 years of university education in South Africa. She was the first women to receive a D.Sc. from Unisa'a predecessor, the University of the Cape of Good Hope in 1914 / This thesis researched a mango disease which caused considerable loss to mango growers in South Africa at the beginning of the twentieth century, particularly around Barberton, Warm baths and the coastal region of Natal. The disease caused dark angular spots on the leaves. This did not noticeably affect the general health of the tree, but served as a source of infection for the fruit. The infected fruit is detached from the tree by the slightest air movement and falls rotting to the ground. The infection is carried by wind and rain. Several spraying experiments were carried out at Barberton in an orchard placed at the author's disposal by Messrs Winter Brothers during an exceptionally dry season, which showed that spraying with Bordeaux mixture, iron sulphide or Hyco/ was useless in checking the disease. The disease had not been described in the literature before. According to the author, the cause of the disease was a flagellate bacillus Bacillus mangiferae. It invades the parenchyma, wedging apart and killing the cells and causing gummosis, but it does not touch the lignified tissues. The organism is described, and was tested in detail in laboratory experiments and a resume of its salient characters is given in the thesis / Agriculture and  Animal Health / D.Sc. (Botany)

Fusarium subglutinans sensu lato is a complex of fungi, which are the causal agents of important diseases on a wide variety of plants. Two important diseases caused by F. subglutinans sensu lato are pitch canker and mango malformation. F. subglutinans sensu lato isolates causing pitch canker on pine trees have been described as a separate species, F. circinatum. whereas F. subglutinans sensu lato isolates associated with mango malformation have not been formally described. The objective of study was to clarify the taxonomy and population genetics of the pitch canker and mango malformation fungi residing in the Gibberellafujikuroi complex. The introductory chapter of this thesis provides a review of the taxonomic classifications used for Fusarium spp. in the G. fujikuroi complex. In addition, the current knowledge pertaining to the population structure of the pitch canker and mango malformation fungi is discussed. In the second chapter the occurrence of F. circinatum was investigated in Mexico. Fusarium isolates were collected from pine trees in Mexico and identified as F. circinatum. Morphology, sexual compatibility studies, pathogenicity tests and histone H3-RFLPs were used to identify and characterize this fungus. The pitch canker fungus, F. circinatum and its teleomorph, G. circinata has been recently described. However, the name G. circinata is invalid, because insufficient information was provided to characterize the type specimen in the description. Additional information and a selection of F. circinatum isolates were, therefore, obtained and studies were undertaken in order to validate the description of G. circinata. The teleomorph G. circinata was validated and morphological criteria were shown to clearly distinguish F. circinatum from other F. subglutinans sensu lato isolates. Chapter four presents a study aimed at better understanding relationships between populations of F. circinatum from different geographical areas. For this study co¬dominant molecular markers were developed. These were then used to determine the genetic diversity, genetic distance and migration between different F. circinatum populations. Analysis revealed a high diversity in the Florida population and a low diversity in the South African population. Genetic analysis also indicated that the South African F. circinatum population originated in Mexico. In chapter five, the influence of sexual reproduction on the F. circinatum populations sampled over ten years in South Africa were studied. Sexual compatibility, vegetative compatibility and allelic diversity that were determined using polymorphic markers, developed in chapter four, were used. These results suggested that sexual reproduction is occurring more frequently in the more recently collected populations than in the initial population. Mango malformation is an important disease in mango growing areas. The study presented in chapter six indicated that this disease is associated with two distinct Fusarium spp. in the section Liseola. The two new Fusarium spp. are thus described as F. mangiferae and F. sterilihyphosum using morphological criteria In chapter seven, the distribution and vegetative compatibility of both F. mangiferae and F. sterilihyphosum was determined for the South Africa populations. Results revealed that each of these species differ in their distribution in South Africa. Vegetative compatibility tests also suggest that both species represent single genets in South Africa. Fusarium subglutinans sensu lato isolates associated with pme and mango are economically important fungi. The focus of the studies presented in this thesis has been on the taxonomy and population genetics of these fungi, with special reference to their occurrence in South Africa. Each of the chapters will contributes towards a better understanding of the taxonomy, population genetics and biology of these fungi. / Thesis (PhD)--University of Pretoria, 2006. / Microbiology and Plant Pathology / Unrestricted

Please read the abstract (preface) in the section 00front of this document / Dissertation (MSc)--University of Pretoria, 2002. / Microbiology and Plant Pathology / Unrestricted