STUDIES ON WITCHES’ BROOM OF LONGAN II. TRANSMISSIVE APPROACHES

The transmissive approaches of witches’broom longan were studied. The diseade can transmit through seed, budwood, insect and dodder. pollen may carry the virus. But it can not transmit through a rubbing way like sap.The transmissive experiments with insect during 1985-1989 showed that tessaratoma papillosa Drury and Cornegenapsylla sinica Yang et Li could transmit the witches’ broom, which could furnish us a convincing evidence of why the disease could spread in the orchard and which could help us to set up a principle to prevent the disease by control of the insects.Unclean seed and budwood, earring the virus more or less, would substantially damage production owing to the fact that not only can cause the seedling and grafts to be diseased, but also can transmit and spread the disease through unclean seed and budwood and plant when they are transported to disease-free area or a new orchard. In order to prevent the witches’ broom of longan from spreading, it is recommended that the quarantine measure should be enforced; diseasefree plants should be propagated and cultivated and the insects concernedshould be controlled.