My electric fence has treated post for the gates and corners. The fence is over 10 years old and the post have never had anything covering the tops. I have not noticed any damage. I am talking about large post, big enough to sit a pie tin on top. There are some old fence posts on my property that go back to the 1940's. I don't believe enough rain would stay on top of the post to cause any rot.

My electric fence has treated post for the gates and corners. The fence is over 10 years old and the post have never had anything covering the tops. I have not noticed any damage. I am talking about large post, big enough to sit a pie tin on top. There are some old fence posts on my property that go back to the 1940's. I don't believe enough rain would stay on top of the post to cause any rot.

Sorry about the double response, don't know what caused it, operator error I am sure.

In a wet environment, (in my opinion) anything you cover a fencepost with, is just going to keep in moisture and encourage rot.

That said, what I do every couple years is walk out to my wood posts with a couple tuna cans. They have a couple tiny holes in them. I put them on the posts, and pour a couple ounces of that nasty green oil, and walk away. Within a half hour, all that preservative has soaked into the top inch of the post. Good for another couple years I figure.

Now, getting to the bottom of the pole, I haven't figured out yet. ;)

I keep my posts in a dry climate. They rot off below the ground, but not above!

Seriously, you might try capping the posts. Cut the bottom 6" off some 2 litre pop bottles and put them over the post tops if you have any around, otherwise use other plastic bottles or larger tin cans. Just don't get them too tight so there will be air circulation and moisture doesn't get trapped inside. That would keep the rain out. Otherwise, treating with wood preservative periodically or oil as suggested above sounds good. Plastic bottle caps would need to be replaced periodically as they deteriorate in the sun, probably annually.

You will pretty much have them rot off at the bottom before you have any problems with the top. I have fence posts on my property that are over 50 years old and the tops are good but the bottoms finally rotted.

Another thought occurred to me:
We have a rather famous fence on one of the roads out here. The property owner started putting his old boots over the fence posts quite a few years ago. I'd guess it protects the posts, and everybody knows where they are in relation to the 'boot fence'. ;)

Here is what I used on my Pole Barn, Deck, and Fence. Some pics from their site.