questions: asking about the control measure to control immature fruit drop problem in coconut at the age of 13years. 
 answers: suggested to apply recommended fertilizer like-urea@1.5 kilogram/plant,ssp@2.5 kilogram/plant,mop@1.75 kilogram/plant,borax@50gram/plant.fertilizer should be applied in two equal halves twice in a year to a trench of 10-12 centimeter depth,30 centimeter breadth with a radius of 1-1.75 meter  away from the main trunk.