A virus disease of tea in the up‐country districts of Ceylon is described which is known as ‘phloem necrosis’ from the characteristic internal symptoms. External symptoms including leaf curl and zigzag and dwarfing of the shoots are of less constant occurrence and appear to be much influenced by climatic and growth conditions generally. Severely affected bushes are rendered entirely unproductive. The disease is shown to be transmissible by grafting to certain types of tea, nine clones of various origin having been infected so far. In others, of the type commercially favoured for replanting, no symptoms are produced. These have proved to be symptomless ‘carriers’ capable of transmitting the disease to further susceptible scions. The theoretical aspects of the results are discussed, considerations of control and the practical significance of the ‘carrying’ capacity being left for a