Synopsis
Glyphosate is a non-selective, systemic herbicide that can
control most annual and perennial plants. It controls weeds
by inhibiting the synthesis of aromatic amino acids necessary
for protein formation in susceptible plants. Glyphosate is
strongly adsorbed to soil particles, which prevents it from
excessive leaching or from being taken-up from the soil by
non-target plants. It is degraded primarily by microbial
metabolism, but strong adsorption to soil can inhibit microbial
metabolism and slow degradation. Photo- and chemical
degradation are not significant in the dissipation of glyphosate
from soils. The half-life of glyphosate ranges from several
weeks to years, but averages two months. In water,
glyphosate is rapidly dissipated through adsorption to
suspended and bottom sediments, and has a half-life of 12
days to ten weeks. Glyphosate by itself is of relatively low
toxicity to birds, mammals, and fish, and at least one
formulation sold as Rodeo® is registered for aquatic use.
Some surfactants that are included in some formulations of
glyphosate, however, are highly toxic to aquatic organisms,
and these formulations are not registered for aquatic use.
Monsanto’s patent for glyphosate expired in 2000, and other
companies are already selling glyphosate formulations