Looks like several things. Too small a pot, probably poorly draining potting soil, definitely not enough light, and fertilizer burn (which is what is burning your leaves). What potting medium do you have your tree planted in, what kind of fertilizer are you using, how strong, how frequently, and are you applying in on dry roots, and what supplemental light source are you providing your little tree? Is it sitting in a drip pan to catch excess water (I think I see one, and that is guaranteed demise of any citrus tree - wet roots).

Patty S.

Thank you for your reply Patty. I think the sun is fine as this is a south facing window, and the large pot behind it is the mother plant which has been doing great there for years. This picture was taken at dusk, so it looks like a lot less light than they normally receive. I have both potted in standard potting soil. But I think you may be onto something with the fertilizer. I've learned over the years to add a bit extra nitrogen to the mother plant if her leaves started to turn yellow. However, I may have given too much for such a young plant. I have repotted it, and will go easy on the fertilizer and see if that brings the young plant back. Thank you for your help.

I would say over fertilizing see how defined ure leafs are. WHEN i over fertilize my lemon trees they do the same thing. The leaf become huge and over defined.