Things not dying is a clue. I am aware of the nuances involved in public area weed control. Johnson grass hit with Arsenal or Velpar does not grow back. I have what is called Napier grass and itch grass in Hawaii. Those grasses are inherently resistant to glyphosate. A treatment with glyphosate normally partially kills it only to have it grow back from the clump. 1 qt per acre of Arsenal kills it and keeps it dead.
They who can give up essential liberty to obtain a little temporary safety, deserve neither liberty nor safety.
Benjamin Franklin 1775
Sell not virtue to purchase wealth, nor Liberty to purchase power.
Benjamin Franklin Poor Richard's Almanac1738