Okay, thanks a bunch! I don't believe I've ever posted here before, or if I have, it has been a long, long time. Thanks for your quick answers to my questions. I'll work on the fertilizer problem by visiting a nursery and seeing if they have the citrus fertilizer and then doing the fertilizer weakly weekly or 4 times a year. I read somewhere on here that it shouldn't be fertilized while it is setting fruit. But the full sun issue will be a problem. We now live in a house that is very high off the ground - about 17 steps total. I'm not sure my hubby and I are up to moving this heavy tree up and down those stairs either. We can try to get it out where it may get a little more sun. But if we move it downstairs, I'm not sure we'll ever get it back upstairs and there is absolutely NO sun whatsoever in our basement where we would have to bring it back in next winter. Plus we have to have the plastic UV sheets on our window where the tree is in the winter because the room was probably 20 - 30 degrees hotter without it and was impossible to cool. Maybe I should just give this tree away, but I hate to since I've carried this baby around since 2004 and nursed it through years of growing. I'll probably do the best I can with the sun, and I thank you bunches for your great advice.

That's a nice tree. That looks like leafminer damage--the key is the silvery tunnels that form within the leaf and the subsequent deformation/curling of the leaf, followed later by browning of those areas. You can have some areas of leaf curl as well with aphid infestations, and browning patches can also be from significant wind damage, but the trails and the substantial browning point to leafminer. As to control: the party line seems to be that if your tree is 'mature', the damage from leafminer is merely of cosmetic importance, and your tree looks like it has plenty of photosynthetic machinery. But, if it starts to look like it is really hampering your tree or if you are worried about it spreading more than it has, then the agent of choice is apparently spinosad. However, I don't have any experience with it whatsover,and a reasonable choice to look into would be neem oil applied properly ( ie--be wary of burn if it is very hot and sunny). Thats what I would start with in fairly frequent application initally, along with manual squishing of larva and pupae in the trails--they're little nasty worms the size of a grain of rice. The ants don't have a lot to do with this particular problem, but eliminating ants helps if you have any concurrent pest problems like aphids and scale and other tasty things. You can try traps laid out (especially near the colony) if you don't have a risk of pets or kids getting into them--if they don't get watered, then they shouldn't leak any pesticides on your soils. If there are just a few, you can also merely hose them off your tree repeatedly. They tend to get the message. Manual removal of any aphids or scale will discourage the ants too--just disrupt that symbiotic relationship somehow. The relative paleness of the leaves could be a number of things, including nitrogen deficiencies, soil temps, watering issues, lots of youthful leaves, etc. I have no idea what kind of soil you have in your garden but since we Californians have had a very dry spring, I would encourage you to make sure you are getting enough water to the roots. If the roots can't get enough moisture or they are drowning in too much, they can't take up any nutrients. Are the surrounding plants brown from winter cold or is it just really dry?--that will give you a clue as to what you might need to do. Also, you can apply some nitrogen-rich fertilizer if that hasnt been done recently. I use an acidifying fertilizer with iron in it, since I have alkaline clay soils. The proper thing to do though is to get a soil test to see what you might need to do with it. It's normal for citrus to lose a substantial amount of forming fruit, and if they don't drop right away it can just dry up and look like what is in your pictures. That is not directly related to the leafminer nor necessarily pathologic. The dried baby fruit can also be from relative dehydration or from buffeting winds as well--your tree will need enough water to properly fruit. HTH.

I want to add that it is good for Citrus roots to dry out some before watering but not to drought levels. I know what my potted trees weighed when dry planted and after I soaked them for the first time. When the soil is just a little heavier than dry it is time to water the trees. I do not let the soil get as dry as when I mixed it up from dry. That is drought levels and could hurt the tree. your tree should do fine once it comes out with new growth.

Looks like old damage. Suggest you mark each spot with a permanent marker and, then, check every several days to determine if more damage is occurring.