You have your detail texture set to a grass texture.First, download this texture and save it to the location of your map:Then open your map in game, open the mission editor and; hit F3, expand MissionGroup - SimGroup on the top right, click Terrain - TerrainBlock, expand the button titled "Media" and where it says "detailTexture" type in Add-Ons/Map_[your map name here without brackets]/detail1 and hit Apply.