Emrys Davies wrote:
I know how glyphosate works on a plant and the soil but I am wondering
if it is safe in the following circumstances:

If it is applied to weeds on concrete paths, allowed to completely dry
and then it rains is there a danger that the residue can then be carried
on shoes onto grassed areas and thus cause damage?

I suspect that it depends how clean the concrete path is. It won't take
very much clay soil dust to adsorb the glyphosate but until the stuff is
bound to clay it is water soluble, mobile and still potentially active.

And grass is exquisitely sensitive to glyphosate so you do have to be
careful not to walk across a lawn with boots wet with the spray.

I have never had a problem with spray on concrete path joints migrating.
YMMV

But for a concrete path with joints something a bit more noxious like
"PathClear" may well do a better job.

Regards,
Martin Brown
** Posted from http://www.teranews.com **