Abstract

Mycoplasmas or rickettseai have been implicated in more than 25 tree diseases. Of these spike disease of sandal (Santalum album L.) caused by Mycoplasma like organisms and citrus greening of Citrus sinensis (L.) are the important diseases in India. Electron microscopic studies showed that the causative organisms of the two diseases differ in their ultrastructural morphology. Cytochemical tests showed the presence of polysaccharides in the outer membrane of citrus greening agent, indicating its resemblance to rickettsia