Abstract
In 1979, a disease of sickle hare's ear (Bupleurum falcatum L.), characterized by the symptoms of yellows, stunting of the plants, and sometimes witches' broom, was observed in Sakai Town, Fukui Prefecture in Japan. Electron microscopic studies revealed the presence of a large number of pleomorphic mycoplasma-like organisms (MLOs) in the sieve tubes of diseased plants collected from the field, whereas no MLOs were found in the control plants. Of the two leafhoppers, Nephotettix cincticeps Uhler and Macrosteles orientalis Virbaste tested, only M. orientalis was found to transmit the disease. The host range of the disease was tested by allowing infective leafhopper vectors to feed on 117 species of plants belonging to 31 families. Among these, 62 species of plants belonging 21 families was infected, including spinach, turnip, radish, Chinese cabbage, eggplant, Nicotiana glutinosa, onion, welsh onion, lettuce, garland chrysanthemum, carrot, parsley, water dropwort, Japanese hone wort, white gourd, pea, broad bean, white clover, pumpkin and sesame. Out of the experimentally infected species of plant MLOs were recovered from 52 species belonging to 20 families by back inoculation to Japanese hone wort seedlings.
