HELP!!! My lemon tree leaves are turning yellow!!!
I've bought a lemon tree a couple of months ago and it've been doing quite well (a lot of new growth and flower buds) until about 2 weeks ago. Its leaves (only 2 now) are starting to turn a bit yellow! The new growth also looks pale green (it thought it was normal but it's been like 2 months that way without turning dark green so I am starting to think if something is wrong). PLUS the fruits drop dramatically (It used to have like ~80 small fruits on and lately it drops about 5 to 10 / day, now there are maybe only 15 on the tree).
I give it deep water once every 2 days, apply liquid fertilizer weekly (about 10ml dissolved in 1 liter used on 2 trees). It gets almost full sun (south-facing window). Do you think it's getting sunburn? Or some iron / magnesium deficiency?
I'm totally new in this so please help. Any advice / suggestion is highly appreciated. Thanks in advance guys.