On Sun, 11 Apr 2004 19:32:31 +0000 (UTC), Franz Heymann wrote:


...glyphosate or paraquat...
Those two very effective weedkillers attack only the
green parts of plants and both are inactivated quite quickly once they
are in the soil.

Glyphospate translocates throughout the plant and kills both root
and leaf. Paraquat acts as you describe. That's why glyphosphate
is effective against couch grass and paraquat isn't.

It's true that what falls on the soil is deactivated in both
cases.

BTW, for the benefit of the original poster, a warning: Be very
cautious with paraquat. It is a nasty poison that can kill you if
ingested. In particular, be very careful, if you use it, to mix
it in a container that cannot be mistaken as containing a potable
liquid -- no pop or milk bottles, iow.


--
Rodger Whitlock
Victoria, British Columbia, Canada
[change "atlantic" to "pacific" and
"invalid" to "net" to reply by email]