Sorry in advance for the giant pics, I dont have any kind of picture modification programs to crop it with. But hey, its easier to see.
I have an existing orange tree of unknown pedigree. It has had its issues, for one it is right over a septic tank cover and was injured a while back for the inspection and then last winter we had a fluke freeze and the top branches died. I topped it off and it seemed to be doing better with new flushes of leaves all over. We have had some cooler weather all of a sudden, like it went from late 80s to 58 degrees at night. It was enough my plum trees dropped their leaves and pears seem like they will follow suit. I checked today and if you can see in the pic, the ground is littered with fallen leaves. Is this normal? Imageshack is slow as hell but I will load better pics.



Here is a Honey Sweet Orange I have been nursing. What is wrong with it? All the deficiencies look the same to me so at one week intervals I have added zinc sulfide foliate spray, iron, manganese sulfate, magnesium sulfate and this is what I still have to show for it. What gives?

Probably nothing. It is natural for citrus trees to drop many leaves during and after a flush of new growth. I grow many different citrus cultivars which recently have produced both new growth flushes and flowering. Many of them are presently discarding leaves. Citrus normally drop some of their older leaves in the spring and fall. Further, looking at the coloration of the tree's leaves they seem generally fine, with a vew rewer leaves showing some iron deficiency. I also noticed a cople leaves showing a pattern of manganese deficiency, but I would not worry about them at all, a few leaves on a tree frequently show this from time to time, especially near fruit. - Millet

With that much leaf drop and dieback on the branches (unless you think that is just from the freeze), I would be concerned about over watering and root root. You might try pulling back the mulch that seems to be around the tree and cutting back on water, if you are irrigating Is there any evidence of gummosis?