Answer: Champaca usually grows in full sunshine without problem so I'm not sure why the leaves would show symptoms of sun scald. If the areas in question turn a tannish color, it probably is sun scald - perhaps the tree has been fed too much and the new growth is rapid and tender? If this is the case, simply hold off on fertilizer and allow the growth to develop more slowly. If the areas are dark brown rather than a tan brown, it could indicate a fungal disease (poor air circulation, not enough sunlight, etc.). You'll need to move the tree out from under the overhang to provide more sun and better air circulation.
Best wishes with your tree!
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