Ugli not looking well, any advice???

[PM239]

I have 36 citrus trees, all purchased at the same time, same pots, same media, all variables the same. 
This is the only one like this???

[SonnyCrockett]

Maybe just over-watered?  I'd pull it out of the pot and take a look at the roots.  If they are nice and white and firm, that's okay.  If they are black and mushy, it's been over-watered and the roots are rotting.

[PM239]

Thanks

[Millet]

Looks under fertilized to me, the leaves has the symptoms showing a nitrogen deficiency.  What fertilizer do you use, and what if you fertilizer regimen?

[PM239]

I bought them in the commercial 4" pots, planted them in 15gal pots.
I left them 2 months with no fertilizer, and since then I fertilized Dec 1st and again Jan 1st with a 1/2 cup of 10-10-10.
The potting soil I have drains very well, but will hardly grow a weed, lol.
Admittedly, I am a bit scared of possibly over fertilizing

[Millet]

Going from a 4" container to a 15 gallon pot is normally a real killer.   From a 4" container into a 1-gallon container, then into a 3- gallon container and into a 5-gallon container and on and on is best. 

[PM239]

The pot they come in are 4" wide, but deeper than 3gal pot

[Millet]

According to research citrus absorb nutrients in a 5-1-3 ratio. Meaning for every 5 parts nitrogen the tree absorbs it will absorb 1 part phosphorous and 3 parts potassium, plus trace minerals.    The 10-10-10 fertilizer you used has a 1-1-1 ratio.   Try to find a fertilizer that has  higher levels of nitrogen and potassium and low levels of phosphorous.  Be sure it also has trace minerals.  A half cup of 10-10-10 per a 15 gallon container is a lot of fertilizer.

[PM239]

Thanks again, I always appreciate the lessons!!