Its very hard to tell what that is from the picture...but if its a bug there's a good chance it is hindering the new growths? Can you spray the tree with some soapy water...a couple of drops of Ivory dishwashing in a spray bottle...but make sure you do it in a shady location prefably very early morning or early evening and then rinse it with Plain water after a few minutes once you think the bugs are dead...soapy water in the hot sun could sunburn your leaves...

You may have to re-spray in case there's eggs as well...

Good luck!

Sounds like water- not enough,or too much at the roots. Not enough to feed young leaves..or the soil has gone bad,and is affecting the root system.

The white thing looks like a small bead of mango sap to me.

DM

This is normal. Those early "incomplete leaves" always fall off, and the well "advanced" leaves would come out. The latex color sap is normal during a strong grow sprout. keep doing the same routines.

Sapote

Thanks all for your answers. Nancy, I sprayed that part last weekend with a homemade solution made of natural black soap (paste) with a little bit of vegetable oil and methanol. I use this for mealybugs and aphids, and it works. The bad part is that I did it in full sun and forgot to rinse it with water afterwards!

Stan, this NDM had a nice flush a few weeks earlier, with healthy leaves. Would you still believe that it could be the soil or the watering?

Dangermouse01 and Sapote, how would you explain that black dot at the tip of the sap?

I will check if is there any improvement when I'll be back home for the weekend.

Jalilu

black dot at the tip of the sap? The early ooze out sap had got darken or syrup like substance oozed out in the early stage had changed its color before the white sap came out. I saw this on my new spout all the time.

Sapote

You are right. I found more sap exuding from other mango trees, and also white spiders on one tree and mealybugs on another.