questions: telling that he has a 5 numbers of orange trees but the leaves are small sized, chlortic crowned and the tees start declining. asking why this is happening and the preventive measure for the same. 
 answers: replied that it has been due to zinc defiency which is considered as the most wide spread and damaging micronutrient defiency of citrus. zinc sulphate solution @ 6 gram in 1 litre of water has been suggested to spray during new flushes.