Copper Sulphate (light blue crystals) AKA Cupric Sulphate. Kills roots
but not necessarily the tree.

Had it recommended to me several times but I am concerned about toxicity
It Works but is generally toxic to everything at levels required to control
roots. It will kill bugs, worms, fungas, algae, and everything that makes
soil alive.

In trace amounts is a nutrient, in slightly larger concentrations is used as
an algicide in pools and a fungicide on farms and in highest concentrations
a powerful everything-acide and excludes root growth in the area treated.
You can also put a little down the pipe to prevent root intrusion. Dosen't
seem to be a herbacide except where contact is made, a Tree will not take it
up and die.

Plumbing inspector in my town suggested it but I added nothing in the end
reasoning that ABS pipe is stronger than what was replaced. That plus I
wasn't sure if the stuff would migrate to other soils I did not want
sterile. Afterall, copper is considered a heavy metal in the envoirnemnt.

Search on "Copper sulphate herbacide" for more





"bill a" wrote in message
. ..
The tree is on city rightaway, so I can't take the tree out,
unfortunately.
It is already in decline and will probably die anyway in a few years,
but the city always waits until it is an emergency (or has destroyed
property)
before they take them down.

bill

"Goedjn" wrote in message
...


I'm trenching out along a shallow foundation to install drainage. There
is
a few tree roots here and there that I'm chopping out along the way. Is
there anything I can add to the backfill to sterilize the ground so the
roots don't grow back too quickly? I am not concerned about the welfare
of
the tree itself. If it dies in the process, no problem.


Take the tree out first, then.