A Disease of Aucuba japonica Thunb

Trapp, George (1934) A Disease of Aucuba japonica Thunb. PhD thesis, University of Glasgow.

Abstract

1. A description of the symptoms of a disease in Aucuba japonica Thunb. is given. In most cases the injury takes the form of a blight of the terminal twigs, in others a more systemic affection was observed. 2. The histology of typical stem, leaf and root lesions was studied but revealed no certain evidence of parasitic invasion. 3. Isolation from the more recently necrosed parts yielded a constant and, in most cases, pure growth of a motile bacterium. 4. Inoculation experiments with this organism gave negative results. 5. The organism is given specific characterisation and details of its life history are described. 6. The action of the extracted products of bacterial growth was tested on sections of sterile aucuba tissue without positive result. 7. Bacterium-free filtrates of the expressed sap from diseased plants were inoculated into healthy tissues but no lesions were produced. 8. Phomopsis aucubae Trav., occurring generally on the dead parts of aucuba bushes, was unsuccessfully inoculated on vigorous healthy shoots. 9. The parasitism of Botrytis cinerea Pers. was established for experimental cuttings but this fungus was never observed in naturally occurring forms of aucuba disease. 10. As botrytis has not previously been mentioned on aucuba this new type of infection is described symptomatically and histologically. 11. The results of inoculation with mixed inocula of aucuba bacillus and botrytis pure cultures indicate than an antibiotic relation exists between these organisms. The inhibition of botrytis infection by the bacillus may afford an explanation of the non-appearance of botrytis rot of aucuba in nature. 12. The relative claims of the organisms, isolated from decayed tissues, to be regarded as significant in the production of necrosis are enumerated but no attempt has been made to formulate definite conclusions regarding the possible pathologic role of any of them. 13. It is suggested that differences in the degree of incidence of necrotic injury from year to year may be related, directly or indirectly, to the variation of climatic forces.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Keywords: Botany, Plant pathology
• Date of Award: 1934
• Depositing User: Enlighten Team
• Unique ID: glathesis:1934-80024
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 03 Mar 2020 10:06
• Last Modified: 03 Mar 2020 10:06
• URI: https://theses.gla.ac.uk/id/eprint/80024