Dual lightmaps problem

We have dual lightmaps mode
we have a tree , when we are near, it is in the radius of dynamic light and all is ok

when we walk away from the tree, and tree goes out from the radius of dynamic light it turns into static light and we see directional light on tree (no shadow)

light probs doesnt help, any ideas?

thank you!

we cant make radius on whole scene, it will give us low performance