Sure looks like a fungus to me. I now have eight mango trees, first started planting & growing 12 yrs ago, so am familiar. In each of the two locations ( Upper Keys & here in SW Florida ), I have grown mango trees I have faced the fungus problem. But not to worry, Home Depot and most gardening centers sell a blue colored " Liquid Copper Fungicide ", usually in one pint plastic bottles. i just bought two yesterday, will be spraying my trees in next 2, 3 days,..the 3rd spraying this year ! Thats it, should make your leaves nice an healthy in no time, just follow the directions and use a plastic sprayer that attaches to the end of a garden hose, Home Depot sells them also. The two bottles should last me for four to five years.
Hey, if I can do it, anyone can. After one spraying just play it by ear, - spray again if the fungus returns or is stubborn and hangs on after initial spray. I usually spray my trees 2 or 3 times a year. Good luck !

I have the same thing on my mango tree, spraying with a fungicide makes a difference. I have my tree potted and having good circulation helps, too. Keeping the debris cleaned up under the tree takes away a growing medium for the fungus.

Thanks for your help on this. Will spray this weekend.

Sprayed all my trees this morning, took almost an hour. Important to spray both sides of the leaves and also to place a covering underneath, - the trees roots don't like that particular spray.
This is the time to start the anthracose fungus spraying,..once the small flowering pannicles start popping out. If the fungus spots persist, another one or even two sprays, about 2, 3 weeks apart, should set you up in good shape for the coming season. Personally, I would hesitate spraying after April 1st.

This post was edited by jofus on Sun, Dec 22, 13 at 16:35