weedkiller

[Bill Wright]

I've scraped off all the weeds from the gaps between the flagstones. What's the best stuff to pour on the cracks to kill any roots?

Bill

[Andy Burns]

Seems about the only thing mortals are allowed to buy these days is glyphosate ...

[The Natural Philosopher]

'pathclear' is better.

As having scraped the weeds off there is nothing left to absorb glyphosate.

[Andrew Gabriel]

Pathclear is glyphosate plus a germination inhibitor, which will prevent new seeds from starting to grow.

Unfortunately, you should have sprayed it on a few weeks ago and waited until the plants died before scraping them out.

Nothing much will prevent the existing roots regrowing, although you can hit the plants with glyphosate when they do.

[bert]

..and salt.

[Mr Pounder]

Nothing bloody well works. On your knees with a sharp knife.

[The Natural Philosopher]

Pathclear contains no glyphosate at all actually.

[Chris Hogg]

Ammonium sulphamate* watered on as a strong solution, will persist in the soil long enough to kill the roots.

*AKA 'Root-Out'. Not sold as a weedkiller any more but still available as a compost accelerator (thanks, Brussels!). Google for it.

Note: ammonium sulphamate is not the same as ammonium sulphate, which is a fertiliser and will make your weeds grow.

[Dave Liquorice]

flagstones.

Glyphosate(*) does but it needs to be applied to the growing tops and then left for a week or two before:

Or a paving knife:

(*) Watch the concentrations on the branded stuff, some are very low and cost a lot, compared to non-branded concentrate at lower prices...

[Andy Burns]

It does now, paraquat was phased out in 2007, presumably the formulation was changed then.

[Andy Burns]

I have a similar one, "patio hook" I think it was called

Ooh, you've annoyed tinyurl somehow ...

[The Natural Philosopher]

Judging by user reactions 'about as effective as distilled water' it still doesn't contain glyphosate either ;-)

[The Natural Philosopher]

Pathclear WAS three ingredients of which only one was paraquat. the other two were long term weed suppressants. Taking up to 4 weeks to kill weeds and effective for at least 3 moths before dispersal.

The paraquat has gone and may have been replaced by glyphosate but the other two elements I think remain.

Users are split between those who say it works, but takes weeks to do it, and those who say it doesn't work at all anymore.

That suggest to me the glyphosate hass NOT replaced the paraquat: they have simply left that bit out.

After 45 minutes googling, I cannot find a single reliable reference to what is in modern pathclear at all. Its all hearsay from gardeners.

[Dave Liquorice]

Not even with "pathclear coshh" ?

That produces quite a few COSHH datasheets on the stuff, several of which list glyphosate as an ingredient. Might need to be a bit more specific about which pathclear product is being refered to "Pathclear

3" might not contain glphosate but "Pathclear LC" does...

[Peter Crosland]

Any one with glyphosate as the active ingredient. You really need the foliage there to apply it to.

[Andy Burns]

"6 x 18 ml tubes Contains 20 g/L diflufenican and 125 g/L glyphosate formulated as a suspension concentrate"

[The Natural Philosopher]

Any one NOT with glyphosate as the active ingredient, since You really need the foliage there to apply it to.

[Martin Brown]

You have done exactly the wrong ting and just made more work for yourself. Applying glyphosate to the tops would have worked fine if the green leaves were still there killing tops and roots in about two weeks.

The modern "persistent" path weedkillers are now pretty useless and never were much good between flagstones anyway. OKish on gravel paths but still really not much cop at all. Effective ones were all banned.

[harryagain]

Sodium chlorate was the stuff but no longer available due to our muslim friends. So salt (sodium chloride). Road salt is cheapest. You may have a local free source. Dissolve in water and pour on. You need plenty. Wash down cracks with hose if there is a lawn nearby that the salt could be carried onto by your feet. Also appplies to pathclear (not recommended on hard surfaces for the reason above.)

[harryagain]

The other alternative is to blast the cracks out with the pressure washer. Most of the sand/whatever can be washed back in again and the lighter weeds blown away with the jet. (Let dry first)