You do have vurts ashland trees checked in your data files right? If you check them for MGE creation, but don't keep them checked for playing the game, that will happen.
Thanks a lot.
I should have paid more attention to the readme.
Tick Vurt's Ashlands Grass.esp when generating
meshes / distant land in MGE, but do NOT tick
this .esp while playing. This .esp is ONLY for
MGE users!
I left them both unticked (Vurt's Ashlands Overhaul and Vurt's Ashlands Grass) while only Grass should be left untouched.