and this is to compare how a healthier leaf on the left looks next to one that is starting to change color on the right - it's a different shade of green, as you see. No pronounced spots yet, but this is how it starts.

My citron tree is an indoor one, several years old. It lost 75% of its leaves before I was told it is scale. I sprayed with soapy water and also diluted white oil. I fetilized it as well. The pot is about 35 gallons in volume, and the tree stands about 7-8' high. I keep up with the scale, put cannot rid it entirely. Many leaves are yellowing, also curling. Some to have brown patches. I misted the tree heavily with water to rinse off any dilute soap residuer. New leaves are forming, and some flowers, but some of the new leaves just dry up. HOW CAN I SAVE MY TREE?!! Treat the soil? Keep spending 45" a day picking off scale insects? Would an overwater cause a sudden massive leaf drop, or a change to hotter weather? The tree cannot be taken outdoors and is in a northern exposure (not good, I know). Should I buy lights? Please help.

Wow!! What an immense amount of arrogance!! This is why self-proclaimed 'experts' are usually to be avoided or at the very least, their info approached with a large degree of caution. You are so wrapped up in you own self importance to completely ignore what I might have posted. If you care (or even bother) to read more carefully, I did acknowledge the presence of psyllids in my very first post. I am also a practicing consulting horticulturists - not at all an "Internet only" person - and I am actively engaged on a daily basis diagnosing plant issues. I do this for a living!! I am very familiar with boxwood - apparently much more so than you as the self proclaimed expert are - and have encountered all manner of boxwood issues. If.....and I mean if.....leafminers are present, they are not present in any large numbers or the damage would be far more obvious.....as it is with the mites. "You started arguing without possessing much love and experience with boxwood. That`s your big issue. Be careful on such discussion because you can meet real professional . I am not going to teach you for free here and maintain this discussion." Again, wow!! You have no idea what experience or knowledge I might have with this plant or just how much of a professional I might be. I have openly shared my background and experience whereas you just claim yours with nothing to substantiate. And what is the title of this book you supposedly authored?? Perhaps it is the type of scientific research and detailed plant morphology that we could all benefit from. Or maybe it is just another unsubstantiated bold Internet claim...... btw, I have already been taught by a lot of very skilled academic minds. That's what a college degree will do for you :-) I certainly don't require your half-a**ed instructions!!

The leaf surface with the lightest variegation is indeed more susceptible to sunburn. The pigment chlorophyll functions as though it's nature's sunscreen for plants, and the lighter parts of the leaf have much less chlorophyll, so there's more potential for burn. I'd considered sunburn as a potential cause, but discounted it for a couple of reasons. Rachel said her plant was in a state of quiescence and had just started to grow new leaves. She also didn't indicate it was moved into a considerably brighter spot. Any leaves that existed on the plant prior to any new foliage would have already been conditioned to where the plant is sited; and, any new leaves that come into existence would be perfectly adapted to the photo load wherever the plant is sited. Too, many symptoms related to other issues tend to show up in the lighter parts of variegation, notably, over-watering, a high level of dissolved solids in the soil solution, and toxicities of one or more elements/compounds, particularly fluoride which I don't suspect to be the issue here. Given the info Rachel provided, I'd bet the plant was struggling because of too much water/not enough air in the soil, which limits the plants ability to take up and move water efficiently. Increasing the EC/TDS level of the soil solution by adding fertilizer salts further decreases the ability of the plant to make efficient use of water in the soil, which yields a plant potentially dying of thirst in a sea of plenty ...... at least until the issues are fixed. As an aside, I have a variegated F benjamina forest (a bonsai group planting with more than around 9 trees is referred to as a forest planting - fewer trees are a grove or clump planting) with 15-20 trees in it. It sits on a nursery cart on a cement slab in full sun from dawn until around 7PM and there is no sign of sunburn on any of the leaves ...... but that's not to say the leaves can't burn. They can and the lighter areas will prove more sensitive, just as you suggested. Al