I'd say some kind of mites or scale. Spray it with neem under and on top of the leaves. Neem takes 3 days to work and bugs forget to eat and mate, so it should do the trick for you.

Sorry I don't what is it. If you have warm weather then leave them outside in morning sun and keep soil moist.

Are they Manila mangoes?

Sapote

They're relatives to Manila: these are Ataulfo mangoes. And actually I do keep them outside and water them every two days.

Should I keep the soil moister by watering them every day???

*And regarding desertdance's comment, I haven't seen any mites or scales in or around any of my little trees (maybe I have to look more carefully).

What's the soil like? No, I think every other day, watering, is fine - just let the water drain out the bottom. Have you fertilized yet? If you do, only very DILUTE amounts. What is the soil like? Does the plant dry out a bit before the next watering?

Where do you live , Jose? You get lots of humidity? Anyone think it might be a bit of anthracnose? Not sure that's it.....It's when I see the brown crisy edges of the leaf it makes me think it is either a burning (from fertilizer) or a watering issue (either not enough or just staying too wet...)

MyamberMUTT

I keep all my mango trees in a mixture of 50 / 50 MiracleGro potting mix and worm castings and they all seem pretty good and from my point of the view the mix has nice drainage. I don't fertilize them, since the MiracleGro mix already has this kind of pellets of slow-releasing fertilizer. The "every two days watering regime" I keep lets the soil dry between these.

I currently live in Mexico, in the neighbor city of El Paso, Texas: Cd Juarez (it has an arid climate, yet we still have little rainfalls every summer).

Again, I don't think the "disease" is infectious, since the other tree seems to be doing ok...

(The images show the healthy tree which shares the pot with the ill tree) *It was a polyembrionic seed, so I got two trees, but I refer to them as one.

This post was edited by JoseMariaChavez on Tue, Aug 19, 14 at 21:39

This image shows the comparison between the healthy and the ill trees...

I think they are all fine. I never have a perfect all green leaves young mango seedling. After one or two years old they will be stronger, healthier. The tap root is deep so I only water seedling when the pot is light in weight (bottom 1" of soil still moist), while I water those 4 - 5ft ones every other day in warm summer. Constantly wet soil has too many invisible enemies for seedlings to handle.

I don't mean to demerit you and you knowledge, but I kind of been let down by you all... :'( This morning I found the same kind of spots in the other mango tree, and with all my preoccupation went online to find out what was really happening... It turned out that they had LEAF SPOT!!! I'm relatively new in this, so I had barely no idea what was happening...

Now, let me reformulate my request: What, why did this happened, and how can I treat it...???

Thanks, again. I hope that know you'll be able to answer correctly... :(

You're watering it too much. I have a few mango in pots, and they aren't watered that much. If you stick your finger in the soil 1-2" depending on the pot size and it's still moist don't water it.

You can spray with copper which will control what looks like anthracnose. But what you have is bacterial, neem won't help that.

Don't wet the leaves at all and if you must do it early in the day so they can dry out. Folks down here with lawn sprinklers have the same problems when they water their lawns late in the day.

There's lots of info on the web and leaf spot and other leaf blight diseases.

Its a seedling that is having troubles with hot and dry air. Also it could be that a Mango will have some problems with peaty potting mixes. You know what I wish? I wish somebody studied what the formula for the seedlings cotyledon I think its called..the seed that's inside the husk. I've had Aultufo explode to semi adult leaves a nice red..like I was going to get fast growth. Once it exhausted the seed storage reserve,it came to a stop. Its outside in sun and hasn't yet had a second flush.
Whats in those seeds?!..lol.