That's interesting, he did mention using it concentrated. Thanks for the information.
Round up is glycophosphate.
Glycophosphate destroys chloraphyl.
Chloraphyl is the green bits in plants that produce the starches the plants need to grow.
It is only active on plants that are green.
Pouring it concentrated into the tree stup does nothing but cost you a lot of money and pose a chemical hazard.
What is killing the roots is the solvent the glycophosphate is disolved in and using this way is exactly the abuse of the product that the panzies in parliament are using to try and get it banned.
If you drilled holes and poured old sump oil, Parrafin, Deisel , Fuel, epsons salts, vinegar and probably 250,000 other things in there the roots will die.
However root kill is the exact right product to use.
It prevents the transport of nutrient from the roots to the xylem layer where the tree will try & shoot from.
It also contains enzymes that promote bacteria that eat the root material.
Copper Sulphate just kills the roots, and everything else that it comes into contact with and should only be ued as a dilute solution when you want to keep the tree root there as some sort of decorative feature.