Whats the best weedkiller for a driveway prior to having it tarmacced?

I want to treat the weeds myself but dont know whats the best type of weedkiller to use. I have a back sprayer.

Thanks

noah

Depending on the weeds, I would spray with Glyphosphate based Roundup, Gallop etc and treat with a residual Simazine or Gasaron G. If you are dealing with dock or bindweed it will take a couple of sessions or a scrub and brushwood killer to knock these guys back.

I believe that some of the residuals are going off the market soon.

Hope you have protective clothing and face masks to go with your sprayer too.

I would go with Roundup.

instead of spraying could you use one of the black membranes that prevent weeds growing.it would be safer and enviormentally good.
For spraying I find "path clear" very good

thanks all, i was rushing, i have done the preparatory work already and its now at the tarmac stage, everyone around here did not rate the mebrane, said it was not necessary etc. I thought the tarmac guy would spray the weedkiller but apparently its better if i do it myself. I had the driveway prepared initially when the kerbs were done, then guy who will do the tarmac came back and put down 3/4 down, which i have driven over for last 3 months, now getting pushed to get tarmac done. a few weeds have come through, used round up and as usual it rained. Want to have one last go.

So whats the best now???

Off to B&Q tommorro.

noah

Get roundup and pathclear. Apply together.

No guarantees that it will kill the roots, thus your contractor has nothing to do with it in case weeds appear in 6 weeks.

Membrane is the only way to go and get a heavy duty one and make sure it goes beyond the edge of the tarmac

I would be cautious using membrane or Terram as they are only suitable for use below the hardcore. It would normally be used as a stabilising fabric to support the stone base layers.
If used under the tarmacadam directly it will separate the layers and prevent the tarmac binding with the stone. This could result in the tarmac breaking up.

Ideally you would install your wearing course straight after preparing the base layers to avoid contamination with weed seeds. A good thick layer of tarmac should prevent all but the most persistent weed penetrating through.

What you should do is put your membrane under your type 1 Mot, hardcore, before you put you hardcore on place a layer of sand to stop it being punctured.

Sconhome, if you get the wrong type of weed nothing will stop it coming through but for general weeds the above will stop them. The other alternative is to excavate more and put foam concrete or dry lean or concrete in.

Charlie

thanks all, round up and path clear it is then.

noah

CharlieR - we giving the same advice on this one. The problem here is the base is already installed and judging by OP waiting to ensure weedkiller works is not an option. You may have missed that the stone is in place which is why I queried your suggestion of using membrane at this stage. I guess the contractor is aware of the risks of weeds in the subbase which is why he recommended it would be better if OP looked after this factor.

cannot use membrane under tarmac use weed killer called casoron G in powder form when weather is dry it will do the job .

There should be absolutely no advantage in putting down a membrane if the tarmac is laid correctly and to the correct thickness.

Mixing Pathclear and Roundup is a ridiculous idea. Roundup is a systemic herbicide and is translocated around the plant to get into the roots giving better long term control of perennial weeds. Pathclear is a mix of a contact herbicide and a residual herbicide. The contact herbicide just kills off the top growth of the plant, fine on annual weeds, but giving little long term control of perennial weeds. The residual herbicide kills new seedlings as they emerge, but would not be strong enough to give good longterm control of perennial weeds reshooting from established root systems.

The problem with mixing Roundup and Pathclear is that the Pahclear is fast to kill off the top growth and this will prevent the Roundup from being translocated around the plant. (Roundup usually takes 10 to 14 days to take full effect). If mixing with Pathclear you will be getting little or no value from the Roundup.

As mentioned elsewhere above the best approaches are either Gasaron G, or else mix Simazine and Glyphosate.

Glyphosate is the chemical contained in Roundup, it is also the chemical in Clinic, Gallup and Touchdown so choose whichever is cheapest.