Pooping under the Tree

Minx has started pooping under the Christmas tree. His litter box is clean. We've got 3 litter pans in the house, but he seems to prefer doing his business there. Is there anything I can spray on the tree or around it that will stop him from doing this? Thanks

First if this is something new I would have him checked out by a Vet to eliminate any medical problems only then would I consider it a behavioral issue.

Once you've ruled out a health problem, there are a few steps to making sure this doesn't happen again. Make sure you clean the area good with an enzyming cleaner. This helps to lift the scent, which is drawing kitty back. Try putting down aluminum foil or double sided tape in the area. Cats don't like the feel on their paws. Also, spray the area with lemon scented air freshener. Citrus is a repellant!