Though I control the amount of water I use to water it(checking regularly with a meter) I have lost a lot of leaves and branches. It is flowering and the leaves look really healthy but still drop off. However I noticed that on the trunk sap is dripping out and on one of the branches there has appeared a white foamy substance. On touch its sticky like the sap I could not see any creature in it but I am suspecting the tree has been infested by something. Can you help! How can I stop this happening ? Is there a cure ?
You may have several issues going on. I would look for scale insects, and possibly even spittlebugs. These articles should help: