Tim W wrote:

I have never used weed killers. A probably irrational horror of chemicals.
Anyway I have a small area of cobbles, stone sets set in sand (no cement
between or below) and I have been persuaded that a weedkiller may be the
best way to clear the large amount of grass and weeds coming through the
gaps.

I think I have heard that the right chemical will leave some attractive moss
growing but kill the leaved plants. What would that be? The cobbles are
constantly crossed by pets and humans so there is considerable danger of
getting it indoors on the carpets and cats eating it. But I could make sure
the pets didn't go on it for a while.

Glyphosate is pretty harmless considering how lethal it is to plants.
The wetting agents are far more dangerous than the active ingredient. If
you are nervous about chemicals it is by far the best chioce. And it is
very effective against grass (so effective that you don't walk on a lawn
with any spray on your boots). It is more ecologically friendly than
burning the weeds (you get dioxins that way). Avoid the brand name
Roundup unless you really approve of their GM stuff (any generic
glyphosate formulation will do).

If you were a bit more inclined to chemical warfare then PathClear or
something else with a germination inhibitor will give better results on
a path albeit with a slightly nastier hazard. Once dry it is safe enough.

Sodium chlorate will also zap weeds under these circumstances with a
slight fire hazard and some risk of white crystals getting into the
house. It eventually decomposes to sodium choride (aka table salt).

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