Looks like some kind of canker disease, maybe "Eutypella parasitica". I don't think you can save that tree. This post was edited by Huggorm on Sun, May 4, 14 at 11:35

What state are you in? Die back can be from a number of things including moisture problems, citrus pest and diseases. My first impression is that it looks like the rootball is staying too wet. The tree should always be higher than the surrounding yard so the water has a place to go. The retaining wall might be causing moisture problems by not letting water flow away from the tree. The dirt you piled up behind the retaining wall on the right of the photo looks higher than the dirt the tree is planted in. When it rains there is nowhere for the water to go and so it sits in a pool. I hope this helps.

Hi Joan, I would check for spider mites. Look closely they are probably all around the curled leaf and then in and around the others.. The other leaves look green and healthy so i wouldn't worry to much. How is the watering going? Not to wet is it? Let it dry between watering... The buyer 3 in 1 Insecticide is a great product. Make sure you spray on a cloudy day or keep the tree from direct sun after spraying... All over tree. Under leaves too... Good luck!! Laura

OK, from what I read, it mostly peat and has a little perlite..But no bark... If it were me, I would make sure to re pot into a pot just one size up from the root ball so it dries out faster and make sure to flush at least twice a month with fresh water...If you find that the mix is still holding moisture more than 5 days, then I would re pot it into a clay pot....This will force you to water more frequently since it will dry out faster, help prevent rot, and allow you to flush your mix from all the salt deposits more often..It will also force you to re pot every few months before the mix compacts again....Re potting again will not hurt, just make sure you remove as much as the old mix as possible carefully... If you can find bark as Laura suggested, even better! I would leave the dirt out of your mix and just use the bagged...............Glad you came here for help..Hopefully you will stick around and let us know how it goes. Can you take a pic of the ingredients in the fertilizer? I looked that up and it does not say at all..