I have 2 lemon trees and a lime living right near each other indoors under a 110 watt t5 setup. All plants soil is around 70 F and I have a fountain going keeping up humidity. All trees were doing great and mid december they all hit a growth flush and one lemon tree flowered. The tree that flowered I then noticed got infested with aphids. I moved the other 2 away and they are fine. I started to spray the one with neem oil / dish soap and thought I had them beat. I went away for a week and a half and when I came back all the flowers and more than half the leaves have fallen off. I have started spraying again, but am losing many leaves a day. Should I leave the tree growing under the light or let it go dormant? I have an enclosed proch that gets very little light and stays around 45-50 F. Would I be better letting it go there, and the cold hopefully would get rid of any remaining aphids?

thanks in advance

anybody have an opinion?

I suspect your citrus tree drop flowers and leaves because of Neem oil and not because of aphids. Keep one eye on the other 2 trees because could be also infected. What concentration (%) of Neem have you used? If the concentration of Neem was too high, then after spraying an oil band cover the leaves and asphyxiate them, no respiration, causing a massive leaf drop.
As far as I know the max. for Neem Oil is 0,5%. I am using also Neem but with 0.5% concentration.

I don’t think that you could get rid of aphid + eggs due to cold. You should worry about no leaves on your tree and we are just in the middle of winter.
After a citrus tree lost the foliage during winter and kept indoors in short time will be followed by twigs died back, then at the end loosing whole tree.
I vote to let it go ‘dormant’ till spring because of no leaves but this is just my opinion.
Take care!

Sometime spraying the plant is a good thing , but you might need to consider that in winter , at that point if all the "bugs" were gone then maybe the tree is discarding the leaves that were infected and not in use anymore. The tree needs some extra heat and some extra light to recover or indeed to get in the "winter-coma" like someone said somewhere here in the forum

I mixed 1/2 teaspoon neem oil and 1/2 teaspoon dish soap with 1 qt water. The other day I washed the tree down with water and seems to be no more aphids. I have been keeping it under light and the leaf drop has slowed alot. Only lost 3 leaves since friday. In total I would say close to 75% of the leaves were lost.

The leaves that are falling , are those affected , the bottom one's or the new one's?

The one and only source for energy available to the tree is light. If it were my tree I would keep it in the light. - Millet (370 ABO-)

Seems to have stopped droping leaves now, and no sign of aphids anymore. I left it under the light. I lost alot of leaves though, only branches that didnt lose any were new ones from the last growth spurts. The branches that have no leaves are still green though so I guess I should leave them on unless they dry up and turn brown? Thanks to all for there help.

The tree should flush new leaves as it nearSpring. - Millet (368 ABO-)