AbstractsBiology & Animal Science

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