Leaf scorching in Mango is due to

Leaf scorching in Mango is due to Chloride toxicity. Chlorine toxicity can result from air pollution, in the form of chlorine gas, or from excess chloride in the soil. Chlorine is a micronutrient, essential to plant growth. However, too much chlorine can accumulate in leaf tissue, resulting in leaves with a scorched or burned appearance.
This disease is characterized by drying of twigs and branches followed by complete defoliation, which gives the tree an appearance of scorching by fire.
Trees with scorched leaves have brown or dead tissue on the tips, margins, or between the veins of the leaf. Leaf tissue may appear bleached, instead of scorched.