Knotweed and trees...

[Taz Taylor]

Hi guys,

 

Basically, i have been watching a large firm with a knotweed problem on a site and where the knotweed is, is around a row of large TPO'd oak tree.. so felling (of the tree's) and removal off site (the knotweed) to a tip was out the question.

They chose to put a surface barrier in (a 15mm geotextile membrane) to cover the area of knotweed and allow the knotweed to find a gap around the trunk of the tree and treat with glyphosate over 5 years etc..

 

my question is, would having the membrane there still allow the tree go have all the nutrients it needs etc or allow it to still grow and function as normal?

 

May sound stupid to some people, but just asking out of curiosity.

 

Cheers guys.

[Le Sanglier]

Ah good question, we've all seen trees with Tarmac up to the buttresses and extending well beyond the drip line, I have enquired on here how these trees managed to get moisture etc no one seemed to be able to answer it.

I suspect membrane just prevents light so no problem there.

[Gary Prentice]

Ah good question, we've all seen trees with Tarmac up to the buttresses and extending well beyond the drip line, I have enquired on here how these trees managed to get moisture etc no one seemed to be able to answer it.

I suspect membrane just prevents light so no problem there.

 

You do get a certain amount of moisture under Tarmac as condensation, but a tree also traps over half ( I think ) of precipitation that falls on the canopy as runoff down the actual limbs and trunk.

 

Some Tarmac, depending on the quantity of fines in the stone , is fairly permeable .

[Gary Prentice]

Hi guys,

 

Basically, i have been watching a large firm with a knotweed problem on a site and where the knotweed is, is around a row of large TPO'd oak tree.. so felling (of the tree's) and removal off site (the knotweed) to a tip was out the question.

They chose to put a surface barrier in (a 15mm geotextile membrane) to cover the area of knotweed and allow the knotweed to find a gap around the trunk of the tree and treat with glyphosate over 5 years etc..

 

my question is, would having the membrane there still allow the tree go have all the nutrients it needs etc or allow it to still grow and function as normal?

 

May sound stupid to some people, but just asking out of curiosity.

 

Cheers guys.

 

Is the membrane permeable?

[Le Sanglier]

You do get a certain amount of moisture under Tarmac as condensation, but a tree also traps over half ( I think ) of precipitation that falls on the canopy as runoff down the actual limbs and trunk.

 

Some Tarmac, depending on the quantity of fines in the stone , is fairly permeable .

 

Hmmmmmmmmmmmm.......if you say so:001_smile:

[detritus21]

Seems like a complex solution. Why not just stem inject. The glysophate won't come into contact with the trees if stem injecting. Also likely to be more effective than letting it grow through and spraying.

[Le Sanglier]

Back to the knotweed, my mate out here has a riverfront property and when he moved in was infested with it, despite my dire warnings he's just strimmed it and then mowed it regularly, guess what? It died, seeded grass came through. Not quite the apocalyptic plant it's made out to be.

[NI Tree]

Back to the knotweed, my mate out here has a riverfront property and when he moved in was infested with it, despite my dire warnings he's just strimmed it and then mowed it regularly, guess what? It died, seeded grass came through. Not quite the apocalyptic plant it's made out to be.

 

we did the same 20 years ago

[Gary Prentice]

Hmmmmmmmmmmmm.......if you say so:001_smile:

 

Don't have the figures to hand, but I'll get it tomorrow. I was surprised myself when I read it in "tree roots in the built environment"

 

Considering the oxygen levels required for gaseous exchange and root growth, Tarmac and most hard surfacing can't be totally impermeable.

[Le Sanglier]

Don't have the figures to hand, but I'll get it tomorrow. I was surprised myself when I read it in "tree roots in the built environment"

 

Considering the oxygen levels required for gaseous exchange and root growth, Tarmac and most hard surfacing can't be totally impermeable.

 

Sure you're right:001_smile: it's just that surely Tarmac is(or is meant to be) impermeable to water otherwise every frost it would disintergrate.