Well, there are a few things you can try. Firstly, you could try placing a few aluminum foil strips around the base of the tree, as this may deter the cat from climbing. Secondly, you could try using a citrus-based spray, as cats typically don't like the smell of citrus. Finally, you could try placing a few objects in front of the tree, such as a baby gate, to prevent the cat from getting close to it.