how to kill tree roots near trench

[Goedjn]

Take the tree out first, then.

[bill a]

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. Thanks Bill

[Joseph Meehan]

Only killing the tree will do much.

[HeyBub]

Concrete.

[m Ransley]

Copper sheet , there is a copper sulfate impregated fabric sold for gardners needing to keep invasive roots away , I cant find the link. Copper sulfate poured in is a poison but if tree doesnt die roots will grow. Sheet aluminum may work, it is cheap.,Very Heavy sheet plastic is used for Bamboo containment, it is cheap.

[m Ransley]

Dont you use copper nails if you want to kill a tree ? I have a few invasive maples I want dead, Maple roots are shallow and compete with my plants. I thought copper sheet it would not like, but for Bamboo a super invasive plant thick plastic sheet is used.

[William W. Plummer]

There was an old trick to keep a freshly cut tree stump from sprouting

-- pound a few copper pennies into the stump. It has worked for 15 years on a tree I cut down.

NB: "Copper" and "Copper sulphate" are different. The former is an element and the latter is a chemical combination. You cannot infer the properties of copper sulphate from those of copper, sulfur and oxigen which are the components of copper sulfate.

[Joseph Meehan]

Have you seen what tree roots do to sidewalks? :-)

[bill a]

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

[AutoTracer]

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]

[Bob S.]

Coarse salt - comes in 50lb bags.

[JimL]

The safest procedure would be to place a barrier around your drain. Since you already have dug the trench, I would recommend you place a plastic barrier in the trence between the tree and the foundation. They sell barriers at home depot. I just dug one up around my flower bed that was placed there 30 years ago and it show no sign of deterioation.

[BocesLib]

There are a few interesting ways to kill trees. One way IS copper.

Another is to cut a circle around the tree removing the bark all the way around. That should work too.

Another way that I killed trees that were about 5 to 6" in diameter (small) was to drill a few holes on an angle into the tree. I then filled the holes up with those liquid "kill everything" weed and plant killers. I filled those holes a few times and in no time it was dead. (no more leaves and looked like it aged 20 years in only a month) Its good and dead now, just need to yank out the chain saw and cut away.

Tom

[William W. Plummer]

I just stood each penny on edge on the face of the stump and whacked it with a hammer. I wasn't happy about wasting a nickel's worth but anything else would have cost more. NB: Best to stick to real (pre-1982) pennies because the more recent ones are only copper plated aluminum. Ransley suggested copper nails and that sounds OK but you might need more to get the same effective area.

[Goedjn]

[bill a]

do you think salt would be particularly damaging to pvc (the common perf'd drain pipe)? I suppose the salt content in the fill would only last a year or so. thanks bill

[JimL]

I know where some salt was dumped and it's been 80 years without anything growing there yet.