My Namdoc mango is struggling with black soot, I have sprayed copper liquid fungicide at the rate 4-5 tsp per gallon, thrice in the last 1 months at a 7 day interval. I don't see a response, and lots of tiny bugs and white flies onthe plant. Suspected scales and sprayed some malathion last week. Dont' see a whole lot of improvement. Any other suggestions.

Thanks in advance for all replies