Cast a Material Mesh

hi, I’m sorry for my bad English.

I need your help, I want cast into the blueprint à static mesh, but this static mesh is générated into the landscape material, is possible? if yes, how I can cast this

Because I have created à pose system and the grass cross my object and for solves the problem, I want to cast a mesh with box and delete them

My mesh have box colision and have this parameter :