Noob Needs Help: Adding collision to tree trunk/branches, but not to leaves

Hey guys, I created a tree in blender to use in UE4, but i’ve ran into a problem. I turned off collision for the tree’s static mesh so I could move through leaves, but as to be expected, I can now walk through the trunk. The trunk and leaves are two different materials, so I was thinking along the lines of adding collision to the leaves’ material, but I don’t think that’s possible. Is there any way around this? How do you guys use/create trees in UE4? I’m a bit stumped (no pun intended) on this matter… Thanks for reading, have a good one.