In article ,
Terry Fields writes:

Jethro_uk wrote:

My pikey-done tarmac drive to the garage (not used for car storage) is
breaking out in weeds (the tarmac is only tissue-thin).

There's no lawn to either side of the area. Can anyone suggest something
to kill the weeds off for a very long time ? Sodium Chlorate ?

I'm fairly sure that it's now illegal to own and use sodium chlorate.

Try Roundup or the cheaper glyphosate but be prepared to use several
treatments over a period of time.

Use a path weedkiller, which is a mixture of glyphosate to kill
what's growing now (but no long lasting protection in the ground),
and a germination inhibitor to prevent new seeds germinating.
Once you've sprayed what's there, leave it to die without
interfering with it, as that will give it time to draw the
glyphosate into the roots and kill them.

Pick a time when there's going to be at least one day of sun and
warm(ish) weather. Spray generously. Wait at least six weeks for the
weeds to die, repeat if necessary after that time. Next year zap the
weeds as they appear, gradually they'll get less frequent.

For tough perennials, glyphosate works best near the end of the
growing season, when the plants draw nutrients (and the glypohsate)
back into their roots over winter, and the glyphosate gets a long
time to act on them during a period when they are unable to do
anything to resist.

There are some weeds which glyphosate doesn't work well on because
it can't get into the sap, either because it kills the leaves on
contact, or because the plant doesn't absorb it well enough. In
the latter case (e.g. Mares Tail), you will have more success if
you "bruise" the foliage by lightly walking on it immediately
after application. (Don't walk across your lawn afterwards!)
Mares Tail can take a few years of repeated treatments to
eradicate, and in spite of being a very "weedy" weed, has no
problem breaking through tarmac and the resin-based equivalents.
Again, treatment at the end of the growing season is the most
effective, as it continues acting in the roots all winter.

--
Andrew Gabriel
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