I have recently purchased a farm land with around 50 coconut trees. They should be around 8-10 years old as they are all bearing nuts (although the number of nuts borne is very few). I have initiated the forming of a water basin along with application of urea and Farm yard manure. I have noticed white spots on the trunks of many of the trees. The photograph is attached for reference. Can anyone enlighten me as to whether this is a disease or a deficiency and what is the cure?
PS: I have seen nearby arecanut plantations also having some arecanut trees with such white spots on the trunks.