Mango Sprout Suddenly Losing Leaves
About two months ago I planted a mango seed. It was doing very well and had no issues until the past week or two. The leaves began to have wilted spots on them and fall off. It has lost most of the new foliage now, and the older leaves are starting to develop spots as well. At first I was afraid the plant was getting root bound, as it was growing quite large. It did well with the transplant, but the leaf problem has not changed at all. I later noticed tiny white eggs on the underside of the leaves and wiped all of them off with a damp paper towel. All of them are gone, but now the bottom side of the leaves are weeping. I also noticed some small flying bugs crawling around in the soil. I am not sure if the bugs are the problem though, since the small flying bugs have been around for a while and the leaves are still developing more wilted or dark spots. I don't know exactly what the problem is or how to fix it. IMG3810 shows the underside of the leaf IMG 309 shows the wilting bits of the leaf
Certified GKH Gardening Expert
It would seem your plant is infested with White Fly.
You can treat the plant with Neem Oil, this works as both an insecticide and fungicide. It is safe for people and pets.
Here are some links to help you.