Help me identify this invasive weed that is growing through my tarmac

[ProDave]

Tarmac laid about 2 years ago, about 80mm thick that was laid on about 300mm of MOT1 that had been down for many years right from the start of the build.

 

Before laying the tarmac, the MOT1 was re levelled in places and wackered down and there were no weeds growing in the MOT1.

 

Noticed yesterday, this has appeared in 3 separate clumps close to each other on part of the tarmac that does not get much traffic, under our touring caravan.

 

 

It appears to be growing through the tarmac.  I don't think a seed has just landed there and grown.

 

There is nothing else, yet growing through the tarmac and I can't see this weed anywhere else locally.  

 

It is getting a daily dose of Glyphosate week killer until it shows some sign of dying.

 

Any idea what it is?  I don't think it is JKW but it must be something nearly as determined to grow through tarmac?

[Bonner]

Looks like Mares-tail, quite a bugger to get rid of if it is 

[Jilly]

I was going to say I think it’s horsetail too

[ProDave]

So will just persistently spraying it with glyphosate kill it?

 

I am bemused how it got there?  Has it been dormant in the ground for years?  Have it's roots travelled underground for some distance before it decided to pop up there?

[joe90]

Yes I thought mares tail as well, roots go down meters apparently, I had it in a cottage in Shropshire, a right mare (🤣) to get rid of but spraying as you say repeatedly is you best bet I recon.

[saveasteading]

22 minutes ago, ProDave said:

will just persistently spraying it with glyphosate

Yes but you don't get much coating  so it will take years for it to kill the roots. You could try putting black polythene or plywood over it so shoots don't get light.

And cut them back.   I don't know what has to be done with cuttings: segregate in a black bag for an immediate solution.

[Temp]

Put some washing up liquid in the weedkiller. Helps get it past the waxy coating on mares-tail. You might also try walking on it to crack the stems. Let the weedkiller do its thing for a few days before cutting.. 

Edited August 6, 2023 by Temp

[Sarah29]

Yes nearly certain it's horsetail from that pic. And yes v difficult to get rid off using the usual methods. Best way and most permanent is usually to make the soil less hospitable to it (horsetail loves acidic soil).....so if you can access the soil layer (poss through the side water table), you can introduce lime to increase the pH and permanently get rid of the stuff.

 

I've spent too much time talking about this annoying weed with farmers/ecologists. Glyphosate doesn't really do a great job of getting to the roots but it will certainly weaken it if you pull surface weeds and glypho the green shoots religiously. But would really think about tackling it more fundamentally if poss and adjust that pH in the soil...as Joe says the roots go down the metres.

 

Sarah

 

 

 

 

 

[vfrdave]

I have this in my what will be garden and it is a nightmare. Glphosphate hasn't done much for it in my case, however weedol rootkill plus has worked to a degree but it keeps coming back!!

 

@Sarah29 any particular variety/type of lime?

[Johnnyt]

https://www.agrigem.co.uk/diamond-horse-tail-weed-killer-1l

[ProDave]

1 hour ago, Sarah29 said:

Yes nearly certain it's horsetail from that pic. And yes v difficult to get rid off using the usual methods. Best way and most permanent is usually to make the soil less hospitable to it (horsetail loves acidic soil).....so if you can access the soil layer (poss through the side water table), you can introduce lime to increase the pH and permanently get rid of the stuff.

 

I've spent too much time talking about this annoying weed with farmers/ecologists. Glyphosate doesn't really do a great job of getting to the roots but it will certainly weaken it if you pull surface weeds and glypho the green shoots religiously. But would really think about tackling it more fundamentally if poss and adjust that pH in the soil...as Joe says the roots go down the metres.

 

Sarah

 

 

 

 

 

Just how do you expect me to do anything to the "soil" when the only place this weed is present (so far) is coming up through my drive.  The soil is nearly 400mm down, and no I am not digging up the drive.

 

This is the baffling thing to me, why is the only place it has appeared through my drive?  If the roots had come from next door, where I can't see it, why did they travel so far before coming to the surface?  It is just baffling to me.

[vfrdave]

54 minutes ago, vfrdave said:

I have this in my what will be garden and it is a nightmare. Glphosphate hasn't done much for it in my case, however weedol rootkill plus has worked to a degree but it keeps coming back!!

 

@Sarah29 any particular variety/type of lime?

Apologies not weedol but SBK

 

https://www.diy.com/departments/sbk-systemic-concentrated-weed-killer-0-25l/5012042022501_BQ.prd

[Sarah29]

@vfrdave any of the agricultural limes will slowly adjust the soil pH level over time. Use a finer grain for quick release etc. or larger grain for gradual release. Also depends on your soil permeability too etc. Can also pick up one of those simple soil ph meters which will give you a good steer if you're going in the right direction.

 

@ProDave ha no i'm not suggesting a dig up! Liming is a slow/gradual/permanent fix to the issue so you could possibly introduce coarse grain lime along an adjacent flower bed perhaps that naturally drains through the soil under the tarmac....just a thought. 

 

[Kelvin]

 

https://www.progreen.co.uk/blog/kill-horsetail-marestail/?utm_campaign=1738487495&utm_source=google&utm_medium=cpc&utm_content=338772559406&utm_term=&adgroupid=66923715046&gclid=EAIaIQobChMIu8uklPbJgAMVwIdQBh182gFqEAAYASAAEgJ4OPD_BwE

[SteamyTea]

14 hours ago, saveasteading said:

Yes but you don't get much coating  so it will take years for it to kill the roots

I thought glyphosate worked by being transported from the foliage to the root.

Low concentrations of it work well with Japanese knotweed.

[saveasteading]

1 hour ago, SteamyTea said:

transported from the foliage to the root.

Yes. But knotweed has e flat leaves that hold a lot of spray. Horsetail has these little needle things.

Both take many treatments which can be for years.

[Barryscotland]

We have this stuff, spreads like wildfire if left unchecked and nigh on impossible to get rid off. You name it we've tried it from industrial glysophate not the garden centre stuff to salt, salt water, bleach an antifreeze, boiling water, an others. Kills it but doesnt stop it coming back allbeit in smaller quantities each time. There is stuff out there you can buy that is marketed just for this weed but I couldn't see anything on the ingredients different from the glysophate I was using. Check your neighbours gardens for it as well as no point you dealing with yours if there not dealing with theres.

 

Good luck and act NOW before it becomes a real problem

[saveasteading]

I'd have to check but I think it's like fir knotweed...the official way to get rid of it is digging it up. Then you bury it deep.

I'm pretty sure there will be a government guidance document. 

 

On tarmac. Spray and cover and cut.  Repeat.

 

Disposing of the weeded bits?  I looked up the RHS guidance so you don't have to.

Drown them in a bucket, then use the water as fertiliser.

[Kelvin]

14 minutes ago, saveasteading said:

Yes. But knotweed has e flat leaves that hold a lot of spray. Horsetail has these little needle things.

Both take many treatments which can be for years.

It also has a waxy coating. It’s horrible stuff to deal with and the best you can generally hope for is to keep it at bay rather than eradicate it completely. It can obviously eventually damage the tarmac if left unchecked of course. 

[PeterW]

Burn it off and continue to do so - won’t damage the tarmac but stop it before it can grow back and also occasionally flood the area with a weak glyphosate solution but bear in mind that it is neutralised in the soil in 48 hours

[ProDave]

I will stick to glyphosate daily for a while and see what happens.  2 new shoots popped through overnight.  I always believed when spraying with glyphosate you do not cut the weed, you just leave it.

 

Cutting or burning might kill what you see but won't kill the roots will it?

 

The glyphosate I have is concentrated, Gallup XL.  Is there any merit in making up a stronger solution for this job?

[Barryscotland]

5 minutes ago, ProDave said:

  I always believed when spraying with glyphosate you do not cut the weed, you just leave it.

 

 

Mares tail it helps if you bruise plant before spraying. I normally stamp through it before spraying, then leave it to die off which is normally a few weeks after its rained.

[saveasteading]

32 minutes ago, ProDave said:

there any merit in making up a stronger solution for this job?

My understanding is "no". It is absorbed into the system ,  and too much might make a chemical layer and  prevent the leaf doing its photosythesis.

 

As to trimming any shoots. It is better to trim off any new shoots than do nothing, or leave it a few days,  because they will immediately start to build up the roots. 

Likewise, in wet weather, spraying is no use, so trim.

 

If the killer chemical is ok to leave in solution then a small sprayer could be kept handy.

[The Reverend]

Some very good suggestions on here and some no so good. It is Marestail / Horsetail and you do need to keep on top of it. Like Ivy it's best sprayed young before the wax coating hardens, bruising the leaves (weed wiping) is the commercial way of treating it using Glyphosate 360 and an adjudicative like Validate. I have had good results with SBK brushwood killer and Validate but it is suggested to use Kplus(https://www.progreen.co.uk/blog/how-to-get-rid-of-woody-weeds-with-sbk-brushwood-killer/)

 

Burn the weeds and please don't put them in the compost or council green bins as this just spreads the problem.

[saveasteading]

@ProDave do we get an update on this?