I have had good results around my apple trees with rodenticides containing Bromethalin and also with those containing Zinc Phosphide. I alternate between them each year. Attached is a photo from my rounds today.
I accidentally ran an experiment with rodenticide containing the Zinc Phosphide once. I left the container open in my garage. Five hours later I walked back out there and there were two dead voles on the floor. That particular rodenticide is prohibited by the State of California for use on Meadow Voles – but I don’t live there and I am not a vole hugger.