Coconut tree disease

I had two coconut trees in my house and during the last rain, one of the trees died possibly due to water stagnation for a long duration (around a month) in our area. So I had raised the level of soil to 5 feet so that there is no water stagnation around the tree.
But unfortunately my second tree is also getting sick. The leaf on the edges starts yellowing and then the whole leaf becomes brown and falls away. It started from the lowest leaf in the tree and is gradually going up. I am worried one day all the leaf will fall off and its the same way the first tree died.
I am attaching the photos. Can expert please help in saving this tree.

Dear Krishhna ji

Attaching File on Coconut Disease management

Disease_Management.pdf (903 KB)