I'll post some pics when I get home and I've probably already figured it out but just in case I thought I'd ask the experts!!!
I woke up this morning to black spots on my Mango, very tips of new leaves of my Meyer lemon and on a few edges of my DC. It looks like tar but can't be wiped off and it's not brittle or dry.
I upgraded the pot about a month ago and added Miracle-Gro 12-4-8 slow release into the soil which is a mix of 5 parts pine bark to 1 soil. I have always had great results with this mixture in all my citrus and with this banana. It was growing approximately a leaf every 2-3 days under a grow light till I had to move it to the front of the house. I have it under a track light with 4 100 watt CFL's (2@6500K for veg growth and 2@2700K) they will be changed to 4 LED spots as soon as they come in the mail. The front of the house has the ac unit so it is cooler than the back.
I also spray the plants twice daily with water until 2-3 days ago when I decided to add a bit of aquarium fertilizer to the spray for foliage feeding. I believe the black spots are fertilizer burn from the spray at is the only thing I changed with the mango and the Meyer lemon. I also noticed small crystals on the leaves which look like what builds up on the bottle of fertilizer.
I wiped all the leaves off with a wet rag and sprayed with regular water.
Sorry if this is a lot to read just figured the more info the better. Here is a pic of the plant before the black spots! I'll get better photos when I get home!
