My Melia tree is looking really sick and has certain about of die back. It is a very old tree, over thirty or forty years. Covered in lichen. We tried to spray it for that a year or so ago but it is a large tree and hard to get coverage. Also not keen on using chemicals.
Lichen on trees are harmless and are not the cause of your tree's problems - there is another underlying reason why your tree is ill. For more information on lichen, please visit the following link: https://www.gardeningknowhow.com/ornamental/fungus-lichen/treatment-tree-lichen.htm
Secondly, a chinaberry tree (Melia azedarach) typically has a lifespan of about 20 years. So the demise of your tree is probably a natural one.
For more information on the chinaberry tree, please visit the following link: