I don't know of a single fence that doesn't use treated 4x4s for fence posts. Out here in the Pacific northwest, where it is soggy 3/4 of the year, untreated lumber just doesn't last. People do use ceder, but it's lifespan is much shorter. I used ceder on all the posts that touch earth on my coop. But every fencepost around me is treated along with the cross posts. There is simply no way of getting around treated lumber.
Plastic lumber-the stuff made from recycled shopping bags and plastic bottles-is available and seems to do well out here. But it is still way more expensive than wood and who knows what the long term effects of that stuff is.
Finally, if you are worried about treated lumber, run scared from railroad ties. Creosote is probably the most toxic substance know to man that is still used as a wood preservative. Worst of all, there are railroad tracks everywhere...
Plastic lumber-the stuff made from recycled shopping bags and plastic bottles-is available and seems to do well out here. But it is still way more expensive than wood and who knows what the long term effects of that stuff is.
Finally, if you are worried about treated lumber, run scared from railroad ties. Creosote is probably the most toxic substance know to man that is still used as a wood preservative. Worst of all, there are railroad tracks everywhere...