Well it won't grow everywhere. Being a crop plant it will only disrupt life in areas where it gets enough water and such like and it isn't too cold. So we're not looking at a new ice age (thank our lucky stars we didn't do this to phytoplankton or we would). But it will definitely be a weed control problem because it grows so darn fast. Also thank our lucky stars it wasn't mustard seed for biodiesel. Those darn seeds are small...