I believe this is a cedar. Sadly, while working on the foundation for a room addition, it got sprayed with hydraulic fluid when a machine broke. It never occurred to me that I should have rinsed the fluid off of the plant and now there is damage. Can I do anything to help it along or just leave it be?
Presumably it has rained a few times since then. There are soaps that are not supposed to harm plants, but maybe it's too late for that.
You could remove and replace some of the surface soil. Try not to damage roots. You should consider whether the replaced soil needs special disposal effort since it likely has hydraulic fluid remnants in it. That will depend on the nature of the fluid.
You could trim away some of the dead branches. Hopefully the plant will grow over the hole better with the dead branches removed. Considering most of the damage is on the side towards the house this might be a good idea.
If you choose trimming, you want to cut back to just before live wood. Try not to leave dead tips. So go back to a fork where one side is dead and the other is live, and cut off the dead part at the fork. Try to leave as much live bark as possible so the cut spot will grow over.
You could also consider balancing the tree a little. It will be easier to decide after the dead branches are gone. The idea is to encourage an attractive shape, and get light to the parts you want to grow.
Dead branches and tips are problems for a few reasons. They provide places where insects and fungus can get in. They provide a place that ice can build up in the winter. And they don't provide any benefit to the tree.
