Weed killer to prevent new seedlings in block paving?

[fred]

'Premazor 57' works for me on a patio

you may have to go to a farmers store to buy it. Its expensive but does work

[Pamela]

Leo, it's you who's thick but you are so thick you can't see it.

There are NO roots if germination hasn't occurred. Duh!

Stop trying to be the smart arse -- you lack the necessary intelligence. Your stupid comments are making you look a bigger fool than you already are.

[Theo]

Premazor Turbo: Glyphosate IPA salt 31.62% Diflufenican 3.47391%

(I can't find a ref for '57', but Turbo seems to be 57g/l so I suspect it's the same)

so it's basically Pathclear in undiluted form. You'd have to do the numbers as to how it works out when diluted according to the instructions - whether it ends up more concentrated than Pathclear.

It does say it's for "permanently pervious uncultivated land" so seems to be not recommended for impervious block paving.

Theo

[Andy Burns]

Can't see anything sold as "Premazor 57" now, only "Premazor Turbo" which has same ingredients as PathClear i.e. Glyphosate plus Diflufenican, it might be stronger mix?

[Pamela]

Pathclear originally had mostly simazine and I found it very effective but simazine got banned although, for some reason, I still see a few adverts for it.

Pure diflufenican seems no easier to find.

[Chris Hogg]

That is no guarantee against weeds appearing a few years after the paving was laid, even by professionals. Weed seeds blow in, lodge in the cracks between the pavers, sprout and send their roots down to something a bit more nourishing below.

[The Natural Philosopher]

Oh dear. where do you think the seeds are when they germinate. Where to roots will be

Stop trying to be the smart arse -- you lack the necessary intelligence. Your stupid comments are making you look a bigger fool than you already are.

[Chris Hogg]

Despite throwing insults at each other, which helps no one, the argument between you does raise the question as to the mechanism by which simazine and/or diflufenican works. Do they prevent the actual germination, i.e. the swelling of the seed and emergence of the primary root and then the leaf shoot, or do they simply poison those shoots immediately after they have emerged and hence kill the seedling?

[Brian Gaff (Sofa]

Sulphuric acid? grin. Brian

[Brian Gaff (Sofa]

Actually although you may mock, the current legal to use chemicals are not really anywhere near as good as what we used to have, andnature is very good at adaptation. Brian

[Fredxx]

Some people need to grow up and learn to use google.

"The half-life of glyphosate in soil ranges between 2 and 197 days; a typical field half-life of 47 days has been suggested".

Diflufenican seems to persist in the soil:

"products containing diflufenican are applied in successive years, levels of diflufenican will build up in the soil."

Simazine is now banned. Shame you can't get good old fashioned chlorate.

[Fredxx]

That was referring to Pamela, who seems to have difficulty in using Google for the simplest of research, and is abusive to those who point out factoids she doesn't like to hear.

[Mr Pounder Esquire]

There was a narrow channel where my garden wall meets the tarmac footpath. Years ago I scraped the channel out, put weed killer down and used a strong mix of sand and cement. I made a right good job of it :-) Three years later the weeds were poking through the cement :-(

[charles]

depends on what weeds. If it's Mare's Tail it never goes away.

[Theo]

Your post doesn't answer her question. Building up in the soil does not mean it prevents weeds from germinating.

However:

"Diflufenican is a synthetic chemical belonging to the group carboxamide. It acts as residual and foliar herbicide that can be applied pre-emergence and post-emergence. Diflufenican is a contact, selective herbicide used to specifically control some broad leaved weeds, like Stellaria media (Chickweed), Veronica Spp (Speedwell), Viola spp , Geranium spp (Cranesbill) and Laminum spp (Dead nettles)."

"Glyphosate is a non-selective, foliar acting post-emergence herbicide that plays a vital role in many black-grass control programmes."

suggests that glyphosate requires foliage to act upon, and so its presence in the soil doesn't help, but diflufenican can act on some broad leaved weeds before/during germination. However it's not clear that it acts upon other weeds, such as grasses (it's sold for use on wheat crops so presumably doesn't kill them).

A list of what it works on:

"Weeds Controlled Pre-emergence Applications : Charlock, Common chickweed, Common field speedwell, Common poppy, Corn spurrey, Field forgetme-not, Field mouse-ear, Field pansy, Flixweed, Henbit dead-nettle, Ivy-leaved speedwell, Parsley piert, Red dead-nettle, Shepherd?s-purse, Treacle mustard, Volunteer oilseed rape, Wild radish (runch)

Post-emergence Applications: Up to 1 True Leaf: Black-bindweed, Field pansy, Nipplewort, Perennial sow thistle , Prickly sow thistle, Smooth sow thistle

Up to 2 True Leaves: Henbit dead-nettle, Knotgrass , Volunteer oilseed rape

Up to 4 True Leaves: Common chickweed, Shepherd?s-purse

Up to 6 True Leaves: Common field speedwell, Red dead-nettle"

so I can see things like dandelion aren't there. You'd have to wait for them to germinate and then hit them with the glyphosate.

(I have some 'Resolva 24h' which is glyphosate and diquat. Looks like diquat has been banned from 2018 so the new formulation is composed of glyphosate, "D-Glucopyranose, oligomeric, decyl octyl glycosides", "Poly(oxy-1,2-ethanediyl), alpha-isotridecyl-o-mega-hydroxy-", "Propane-1,2-diol", and "1,2-benzisothiazol-3(2H)-one sodium salt". I'm not sure if any of those are active ingredients apart from glyphosate - they're not easy to search for)

Theo

[Mr Pounder Esquire]

To me it was just a green thing that should not have been there.

[The Natural Philosopher]

Doesnt matter if the weedkiller cant get there, does it?

[Pamela]

Quite so. I think there are too many have-a-go experts like Fredxx confusing the picture. Soil accumulation is not the same as preventing germination.

Glyphosate has an action in the folate pathways and these exist separately from foliage. As I recall glyphosate exploits the fact humans can't synthesis folate as plants can and it interferes with a plant's DNA production. (Similarly, if an expectant mother doesn't eat enough folate then birth defects occur, so cheap folic acid is recommended.)

[tony sayer]

Yess how's that done;?...