NOT positive but its possible you have some root rot going on? That happened to one of my potted mango tree and the leaves looks very similar to yours...very droopy. Ironically, by the looks of the tree you would think its suffering from lack of water but in actuality its from soil that is staying way too wet towards the bottom of the pot (perched water) and the roots on mine were rotting. Your potting mix looks VERY water retentive to me...they prefer mix that fast draining, keeping the soil moist not "wet". Is there a way you can very gently remove the plant being very careful with the roots and check to see if the bottom of the pot is very wet? You can also insert a thin (wood dowel) sharpened at one end...insert it all the way down towards the bottom of the pot and see how wet it is. This is just a guess since its hard to diagnose from a picture...Best of luck! Nancy

In the name of saving a few $29.99 3 gallon mango trees, I have already spent a small fortune in products that failed to produced results for this particular circumstance. I replaced the soil in the pots with pricey bagged blends mixed with compost just in case it was a soil borne decease. I have used at both the recommended dose and even at double the dose the following products and additives with no results: Both water soluble 20-20-20 with minors, and premium brand slow release fertilizers with minor elements. In addition I have added to the soil, Ironite in a chelated form, Milorganite, Magnesium Sulfate aka Epson Salts, and Azomite granulated broad spectrum re-mineralizer. I have also used minor elements in sprays (Souther AG Chelated Citrus nutritional spray), and SUPERthrive plant vitamins. I have also used the following fungicides in sprays or soil drenches or a combination thereof: Dithane M-45, Captan, CuPRO, Southern AG Neutral Copper Fungicide, Southern AG Liquid Copper Fungicide, Bonide Complete Fruit tree Spray, and Cleary 3336f systemic fungicide. Believe me when I say that nothing has worked so far. If you are determined on trying something, then by all means try something different then I already have and report your findings. You may want to refer to the fungicide mode of action table to make sure you are not using products blindly that do the exact same thing as the previous one applied. The article below teaches you about this. Here is a link that might be useful: Fungicide mode of action information

It looks like a combination of over-fertilization and bacterial black spot. The bacterial black spot won't kill the tree but too much fertilizer will. It's already dropping young leaves, which is a bad sign. The first priority is to remove the fert and flush the soil. If it lives beyond that, then you can address the bacterial issue. Jeff

Just by chance, did you put in any fertilizer stakes or fertilize them when you bought the house? If so, you might have overdone it with the nitrogen. A heavy nitrogen feed and lack of water will cause leaf drop and that kind of damage. Just a guess though. I would water them and pull up any fertilizer stakes asap. They should recover being such big trees.