once you take paraquat no matter how small an ammount thats it game over, hence way they took it of the market, it does not kill the root bed however...
there is a di-quat sub out in its place now called dragoon.... very good for a quick kill,
glyphosphate, killers will kill the root bed first, normally rainfast in about 2 to 3 hours...
roundup is expensive there are excellent copies out there, weed free, gallup 360, clinic, use about 380ml per back sprayer,
and spray in early morning or late evening so as it won't evaporate in th heat.....
ATB.
Snap.