Candidatus Phytoplasma pruni

Candidatus Phytoplasma pruni is a species of phytoplasma in the class Mollicutes, a class of bacteria distinguished by the absence of a cell wall. The specific epithet pruni means "living on Prunus", emphasizing the fact that the phytoplasma is a parasite of various Prunus species, otherwise known as stone fruits. The phytoplasma is commonly called the X-disease phytoplasma. Like all phytoplasmas, Candidatus Phytoplasma pruni infects both plants and insects. Potential plant hosts include peach, cherry, plum, and others. Known insect hosts include various species of leafhoppers. Since the pathogen can not live outside of host cells, it must be transmitted to a new plant host by an infected leafhopper.

from Wikipedia