Terrain Trees with Custom Script

I have a tree prefab with a script attached to it. The tree prefab has a capsule collider attached to it and set properly around the tree. I have a character object with a collider attached to it as well. Here is my issue:

I am using the OnCollisionEnter. I placed the tree manually into the terrain and play the game. The result was that the OnCollisionEnter was executed, just as I wanted. I then added the tree using the terrain tool and painted a few of these trees onto the terrain. I was able to collide with the trees, however, the OnCollisionEnter event was not fired. Is there a reason why this event does not fire? or am I simply doing something incorrect?

There is a checkbox on the terrain script that says: “Generate Tree Colliders”. It is a really badly labelled box, as it should really say: “Enable Tree Colliders”. Unless that box is checked, colliders will be omitted from any trees you place.