In message , Timothy Murphy
writes
The Original Jake wrote:

I put Roundup on a big patch of weeds about 1 week ago,
but they are not dead yet.
Can I pull up the weeds now without losing the effect?

There will probably not be any effect. Roundup has added agents
(compared to pure Glyphosate) which speed up the effect of the
herbicide (these additions are one reason why many don't use Roundup)
and you will see results often within 24 hours or less. But Roundup
still needs drier weather than we've been having and the weeds need to
be actively growing. Mid-late September is generally the latest time
to apply.

Thanks for the advice.
There has been no noticeable affect so far,
so I guess your and others' warning that I was too late
are almost certainly true.

Quite possibly, though it can take a couple of weeks anyway to notice
the effect on the plants, SO I give a bit longer.

And they don't tend to shrivel up to start with. A yellowing of the
leaf tips is probably the first sign
--
Chris French