Is anybody able to assist me with my lemon tree. I know just about nothing regarding fruit trees so even basic suggestions will do.
As from the attached photo, my lemon tree just isn't right!!
It's been in this spot for about two years, so I don't think it's a soil type issue, and it receives plenty of sun throughout the day (although in shade for this photo

)
But it is very yellow and bare... and not the yellow I want!! Before I planted it I did the soil draining test; and water drained fairly quickly, and considering the rain we've had, the soil isn't that damp so I don't believe its water logged. I've also been giving it RICHGRO Fruit & Citrus fertiliser and Seasol (according to package directions).
There isn't any sign of fungus and it still flowers and fruits (first year fruiting). It did start yellowing before fruit appeared though...
I have two citrus trees nearby that although are growing slower than this fella, are healthy looking
I was also told to trim off the lower branches to make a trunk, is that true?
Thanks in advance!