Tree billboards not displaying correctly.

So I’m making a scene with some trees in it, and I’m having a problem with the billboards. I created a tree with the tree creator, which I then exported to Maya to shift the pivot (in an attempt to tackle trees floating when placed on slopes), and reimported to Unity as a .fbx model. They look absolutely fine until they go into the distance, and become billboards. The billboard seems to contain the shape of the branches only, and in a transparent blue material, rather than the correct colours. I’m using Unity Free version, and I’m hoping someone can help me with this issue.
Thanks.

[13280-tree+billboard+error.png|13280]

I assume you mean Unity Tree Creator. There is a setting for lowering the pivot point. In the tree root node there’s a ground offset bar.

As for the fbx import what shaders are you using? You can only use Occlusion Leaves and Occlusion Bark shader for imported trees.

By the way those are nice trees.