Q.Some of my fruit trees are looking sick,orange,lemon,plum,nectarine. Is it possible I over fertilized.
I fertilized all my fruit trees early July (as I do every year), went away for 2 months & on return the orange tree had 2 branches that the leaves where dying, then the lemon followed suit. I thought they may have wet feet, so I applied anti rot fungicide. No changes so I started a course of seaweed solution. Then the next tree along (plum) has some leaves burning & now the next one the nectarine is maybe starting, 4 months after fertilizing. Is it possible I have over done it ? If so how do I fix it.

Certified GKH Gardening Expert
It is quite possible that there was too much fertilizer applied, but it is also very possible that there is an infection. The more that you try and give it to help it when they are sick, the more it can hurt.
The best thing to do at this point will be to take a soil sample, or contact your local extension service. This will tell you the state of your soil and what it needs and has too much of. Then you can begin to correct the issue.
This link will help you to find the closest extension service to you: https://www.gardeningknowhow.com/extension-search