hi Slashy with old established citrus, I would agree that digging around would not be good. I have about 100 citrus trees and all I ever do (once they are established) is add mulch or compost every year. This does so many good things for the soil including helping lighten it up a bit so that water can work in a bit better. I simply add a thick layer on top the soil, about a hands width will do. Put it all around the tree, reaching out about a 1/2 meter past the reach of the limbs. Sprinkle a bit of water over it to let the nutrients wash down into the soil. In time the mulch will work its own way into the soil (amazing how that happens). Just water enough that some water does make it into the soil. Be careful not to over water as citrus does not do well with wet roots. If the trees are green, how are they getting water now? Keep it up. RE the fruit on the lemon, just start a good mulch and modest water. I believe you will see flowers soon enough. Lemon can flower 2 or 3 times a year, it may surprise you yet.

No, you cannot use vegetable oil. You can find horticultural oils any place where gardening supplies and chemicals are sold. In the meantime, do some googling about 'hortucultural oils' and why they are so useful for the control of scale insects and the suppression of other pests. Scale insects can be a challenge to control. Whomever gave you this particular plant needs his/her glasses adjusted, lol. If these pests are on the leaves and stems......I'm just sayin.

The Sulphur I've only applied once before i left for work 2 weeks ago. I will measure the PH of the soil again soon to see what it is at and will reapply if needed. I've just been watering with regular tap water which is around 7.6 PH here. Every other tree doesnt have issues with it as i think the compost acts as a buffer anyways to bring it down. Same pepper which had sulphur applied also and has started to go pretty well. Blueberries are going super well in pots. Never had issues with them in first place and they are planted in Azalea mix/peat moss/ pine bark with yearly addition of added peat moss/compost and regular acid ferts. Altho i did swear i had more blueberries then this, i think the birds have got to them. On another note to see how rest my garden is going Apricot on its way Peach tree/ Raspberry (which are growing like mental they want to unleash like crazy out of that pot)/ Small blueberry bush 1st yearPeach before i left for work 2 weeks difference when i got back going well this is an O'henry peach Apricot tree growing very well & the Mandarin, both which got battered a bit today but unusual rain at this time of year but should bounce back. Tomatoes/eggplant well on its way in this early spring (just to rub it in for you guys in winter) haha.

Aha - indeed! it should recover to a producing tree... IF the new growth is from above the graft. I cannot the graft in the picture./. unless the graft is where the damage is? If the bottom leaves are same as the top ones that are dying / died then you are in luck. Sometimes the scion will sprout a new shoot just at the graft line and it will all work out. Investigate closely and if you decide to keep it, patience will / should reward you. Do you know by chance where the tree came from (source nursery) and the rootstock?