In Europe there is a herbicide called "Top Gun" (The english name) 
which is 100% biodegradeble in a very short time.
It works like a soap and desolves the cellwalls. plants die whitin
a few hours.


Frits v/d Laan
Organic horticulture
Gouda.  NL
http://web.inter.nl.net/users/F.vd.Laan/