The Role of Fungi and Cultural Factors in the Etiology of Root Rot of Vanilla (Vanilla Frangrans (Salisb.) Ames) in Uganda

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Leakey C. L. A.
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The results of simple experiment are presented showing that Fusarium oxysporum f.s. vanillae satisfies ~he main criteria of the Koch postulates in a way that would be sufficient to indicate it as the causal organism responsible for Vanilla root rot in Uganda. Nevertheless, in the study of root diseases complex interactions between host conditions general environmental conditions, soil microbiological factors and potential pathogens are certainly not exceptional and may be of very general occurrence. In a root rot involving a host plant with a normal mycorrhizal associate the situation is even less likely to be a simple one. Recent work in Puerto Rico has suggested that a major pathogen in Vanilla root rot is a similar, or possibly identical, fungus to that concerned in normal mycorrhiza of Vanilla root, but these studies have been based on few node rooted cuttings rather ,than normally growing vines. A brief review is presented of current knowledge about the behaviour of orchid and other mycorrhizae which is considered to be of relevance to any further studies on Vanilla root rot. Because of the likelihood of complex interactions involving host and environmental factors in the etiology of the disease, it is suggested that attempt to provide optimum conditions for the health and vigour of Vanilla vines may hold more promise for controlling the disease than attempts to control with fungicides pathogens whose behaviour is only partially understood.
East African Agricultural And Forestry Journal, XXXVI (No. 2), p. 207-210