From the looks of your pics, the roots look healthy, and so does the new growth! I would be concerned about using fertilizer this time of year, since I am sure with the roots that bound, you are draining your pot of most nutrients everytime you water anyway...I would give a small dose at every watering. Too bad you do not have FP..It has every nutrient that your tree needs! I would also make sure it is getting Fe, by using a capful of vinegar in a gallon of water at every watering to unlock the nutrients, especially for the Fe that could be in the soil once fertilized..A good Ph makes the iron more mobile and for immediate use for your trees.. Give it a shot. A little fertilier and vinegar just might do the trick...Like I said, the new growth coming in looks great. A sign that you do not have root rot..You are also not loosing twigs or leaves at a rapid rate if at all. Hope it works out

Liz, fertilized soil will not be enough for citrus. A couple of things - first off, I suspect your potting medium is too wet and soggy. I know you've repotted, but none of the container folks here like MiracleGro soil, it just compacts and doesn't breath well enough for citrus roots. If you search for "511" mix in this forum, you'll get a great container potting mix. MeyerMike can help you out with that for sure, his citrus do exceptionally well with 511 mix. Secondly, and due to that, I am suspecting you have something fungal going on. When you see round spots like that, it is almost always something fungal in nature. You don't need a microscope to see mites. I can see them with my 57 yo "mature" eyes :-) Mites give a very classic appearance to leaves, they look speckled or stippled. Your leaves are not displaying that at all. Black spots under the leaves sounds like Greasy Spot to me. You'll need to treat with an anti-fungal agent. Also, a tree that pours its energy into blooming, while failing is a tree that is in trouble. It feels that it is dying, so this is its last ditch effort to reproduce itself. More sunlight, better potting soil, switch to a better fertilizer with micronutrients like Foliage Pro by DynaGro may all help. The fruit that fell off looks like wind damage scarring. I would pull off all the other little fruit right now, and let's see if we can get your little tree to put its energies back into its canopy, instead of the fruit. Patty S. Here is a link that might be useful: University of Florida: Citrus Greasy Spot

Drew, just because your other plants are fine does not mean they will stay that way if you are using the same mix that decomposes like that. You may still have time on others and or may get caught off guard.. Typically, in order to be successful at least a little bit with finer mixes , you would have to re pot every 6 months or less and only pot up in one size. Flushing this kind of mix is a must of any accumulated salts... What kind of other trees or plants do you have and what are they planted in? How are the leaf margins and or very tips of them? I'd bet if you had a palm tree growing in that kind of mix watered that way, the fronds would be all black tips or yellow...How are your other plants leaves, the tips? Are they flawless? If you tap water has magnesium sulfate in it at higher levels, then it can leave white reside as spots behind...Too much of it and other chemicals can also contort the leaves.

Lemon, nice points made. What I don't understand is why you like to work alone rather than a team here. I said much needed points that everyone should consider and it seems as you just skipped right over what I had to say and made your points. Don't you ever agree with anyone, even if these same people thank you for what you have to say and agree with you on many things? Why not add a nice comment to another persons good comment so we can all feel like we are a team helping others here? There are many reasons why many should not re pot at certain times and why many should. There is no ONE SIZE fits all in the re potting process because there are too many variables and reasons why one may have to do one not at the optimal time of the year that's all. It's not that difficult to understand or make sense. Like I said, I would much prefer to do mine at the optimal time of year, being later spring for my area, like around Fathers day, verses the middle of winter, but if for some reason I never got around to it, like a death in my family, I will not put off re potting anything even if it's in the middle of winter or right before they come in for the winter when I finally have the desire or time. I have to clean the roots off completely on certain plants to make sure they are free of root mealy bugs. It has to be done. It's the risk I'm willing to take and I have yet to fail at it. My care and extreme knowledge about caring for citrus indoors, here in Zone 6, New England with very short days, allows me that opportunity where others might fail or learn from me. So we are all here to help people to understand the process in different ways, not so inside the box, with the end result being successful. You can not be so limited that one can not go outside the box in order to encourage good vitality in their trees when it is needed, even in winter. One must not be so limited to such a small window of time like my area, that is it. Sure, when our trees are very actively growing and healthy, is the optimal time, but not one does not take care of sick and dying trees after that period for the long haul of winter. Better to do something then than nothing at all. The big question is, 'how is it that many can have their trees arrive in the dead of winter and still see much success with them after arriving bare rooted and planting them'? That is what we need to do. Help others to be successful at what they trying to achieve even if it's not the best situation or time. Lemon, what do you mean the second problem with citrus here is treating them like Bonsai? Who does? The first problem with citrus here is the soil mix they use, so I politely disagree with you on the light issue. Many here provide enough light and are very conscious of using extra lightning..