questions: asking about leaf rot disease of coconut 
 answers: suggested to go for control 1. physical method: remove the rotten portions from the spear and the two adjacent leaves.
2.chemical method : pour fungicide solution of  sitara (hexaconazole) - @ 2ml  in 300ml water per palm to the base of spindle leaf. 2-3 rounds of spraying are sufficient in case of mild infection.