Billboard trees have white outline

At night, or when my scene is sufficiently dark, I can see that my billboarded trees in the distance have these white outlines to them which are obvious against the dark background. I have tried trees from the Nature Pack, as well as the default trees, and it happens with both of them.

Is there some setting in the alpha channel that I am not seeing? If anyone has an ideas, they would be greatly appreciated!

Are your textures premultiplied or are the backgrounds blending to white? Post one of the textures if you’re unsure.