Current size LOD Problem

I have a problem with LOD system and view size, I need to show the lod 0 of a tree just when the player is very close to the trunk.

To exagerate the thing I set the Lod 0 screen size to 1 and the Lod 1 screen to 0.9999.

But as you can see in the image, you can see the LOD 0 at great distance.

How can i solve this?