I have NO CLUE what your problem is im here to lend you some encouragement till more help comes..in my humble opinion not matter what the problem or plant i have ALWAYS tried to save them and in most cases succeeded. Figure it this way..if they are goners nothing lost anyway..if they are salvageable think of the pride of healing n saving that plant and the knowledge gained. I also figure if something isnt attacking the actual roots its always worth the effort cuz ya never know and then you can share with us your adventure. Best of Luck

What have you got to lose? I would sugest spraying with a good insecticide, it may be aphids, whitefly or a combination. Spray the tops and bottoms of the leaves. Then use the new Bayer systemic granual for shrubs and trees in the potting soil. Within a couple of weeks they should be cleared up. That is my sugestions, hit them from both ends.

I have a similar problem...they are in the ground though. The ones in the direct HOT south Florida sun are the worst. The ones on the north side of my house do not have this problem.
Here is a picture of my problem...