THE STUDY OF DIPLODIA BARK DISEASE CYCLE CAUSED BY BOTRYODIPLODIA THEOBROMAE ON CITRUS 'SIAM BANJAR'

摘要

Diplodia disease is one of important diseases in South Kalimantan, Indonesia. Around 54 % of citrus plantations in South Kalimantan is affected by the disease and causes considerable loss in yield and quality of citrus fruit. No control methods at present are effective or efficient to overcome the problem. In our effort to control the disease, we conducted a research to determine the life cycle of the pathogen. The experiment was done at the Laboratory of plant diseases and at a glass house of the Department of Plant Pests and Diseases of the Faculty of Agriculture-Lambung Mangkurat University in Banjarbaru and at Laboratory of microbiology of the Faculty of Mathematics and Sciences-Lambung Mangkurat University in Banjarbaru. The experiments set infour phases. In the first phase, the work was done to isolate and to identify the pathogen. In the second phase, the work was done to determine the mechanism of infection of the pathogen. In the third phase, the work was done to find alternative hosts ofthe pathogen and in the fourth phase, the work was done to determine the dispersal methods. The results of the experiment showed that the pathogen was Botryodiplodia theobromae. In the infection process the conidia formed infection pegs before penetration and produced a toxin. In the process it was found that the fungus could also attack cashew and avocado. The fungus can be dispersed either by air current, insect (Nitidulidae, Coleoptera), and rain or water splash.