This can be considered as a physiological disorder than a disease
Palms in the age group of 10-25 years are more susceptible
Symptoms are premature yellowing of the nuts when they are half to three-fourth mature
Later splits develop at the tips, which extend longitudinally exposing the kernel
Sometimes kernel also show splitting and malformation
Rarely the kernel inside may exhibit splitting without visual symptoms on the husk, resulting in nut fall
Boron deficiency, hyper nutrition or sudden flush of water after a period of drought or insufficient moisture in the soil is the probable cause (s) of the disease.
Management
Improvement of drainage in ill drained gardens and spraying of borax @ 2 g/litre of water are found effective in reducing the disease incidence
Dept of Agriculture Development 
SFAC Kerala