My parents have a 12' navel orage tree that has contracted the diesease that alot of the citrus trees have in this area since Katrina. I don't know what the diesease is. My dad knows and did what they told him with chemicals. It looked good for a while but it started coming back. He wanted me to take it out, then my mom stepped in and ask me to prune it back. So; what is the diesease in our area? (new Orleans) Can it be cured? Will prunning it back help it? If yes how do I prune it? Any other info will be most appreciated, Thanks in advance.