Yellow leaf disease of Arecanut is caused by

Yellow leaf disease of Arecanut is caused by MLO.
MLO is a Mycoplasma like organism, found in the young sieve elements of areca nut palms declining with yellow leaf disease in Kerala and Karnataka States.
It causes yellowing of the tips of the leaflets. And it extends to the middle of the lamina. Tips of chlorotic leaves dry up. Finally, the crown leaves fall off leaving a bare trunk. Root tips turn black and gradually rot.