rootkill plus runoff

Chris314

I need to use Rootkill Plus on my garden path (nothing else will kill the weeds growing in the cracks etc)
I know the product 'degrades in the soil' but how long does it take to do that ?
In particular, if we get heavy rain (unlikely this year) the runoff from the path goes into a garden border approximately 4 metres away.
Can I assume that the product will have degraded by the time it gets to the border?

debs64

Would a gel weed killer be easier? Less chance of runoff 

Chris314

Thanks but I've tried gel before and it doesn't kill the weeds..

Chris314

I'd be quite happy with using Rootkill as it's the only thing I've used which kills everything (grass/dandelion/that sort of thing) and I use it everywhere else. I find it does take a couple of weeks to work.
I'd still like to know whether it degrades 'instantly' or if not, how long does it take. 
In fact I'd also like a scientific explanation of how it degrades (microbes?) If you trawl the internet some places say the process takes 2 weeks, but others say you can replant the next day !
I think I'm just going to chance it, as there's no forecast of rain here for the next week or more anyway.

Helix

It’s basically glyphosate isn’t it?  The active ingredient in glyphosate is supposed to be broken down by microbes in the soil to harmless substances over a period of time.  I think the half life is said to be about 50 days (so half gone in 59 days, then half of the rest gone in another 59 days etc).  If you have water nearby then much more risky as stays active and kills.

Also be aware that there’s now a lot of debate about whether the claims are accurate that it is broken down into harmless substances within a short period of time.

But are the weeds in your path really that awful that you need to use a chemical?  We have large amounts of gravel paths, paving and so on.  I use a gas gun, which doesn't instantly kill deep rooted perennial weeds, but combined with the occasional half hour of taking them out once weakened keeps the place looking neat.  

Lizzie27

I've used a glyphosate path weedkiller occasionally in the past to kill weeds in our large gravelled car park area which slopes down to a native hedge. In 12 years or so, it hasn't killed the hedge, or crocosmia 'Lucifer' which persists in growing next to it.

glasgowdan

If you've not killed the weeds with basic weedkiller before then you're doing it wrong. 

That stuff won't run off and kill things. It needs leaf contact to work.

PS rootkill has the exact same active ingredient as generic roundup