Glyphosate

Glyphosate (N-(phosphonomethyl) glycine, was used, before the advent of crops resistant to it, as a non-selective herbicide, especially perennial weeds. It kills plants by inhibiting their ability to make aromatic amino acids. It was first sold by Monsanto under the tradename Roundup. It is no longer under patent so it is sold under numerous other names.

Glyphosate is a type of chemical known as a weak acid. Weak acids can donate a hydrogen ion to other compounds. The term ‘glyphosate’ is the common name of the chemical, whereas ‘N-(phosphonomethyl)glycine’ is the chemical name that provides information about the actual chemical structure of the herbicide. Regardless of the brand you purchase, the active ingredient for all glyphosate products is exactly the same.

Glyphosate is a substituted amino acid that interferes with amino acid synthesis by inhibiting the EPSPS enzyme. This enzyme is involved in the synthesis of several amino acids, the building blocks of proteins. Several factors contribute to the effectiveness of glyphosate: 1) The EPSPS enzyme is a part of an important metabolic pathway in all plants. Disruption of this pathway is normally fatal to the plant; 2) Glyphosate binds very tightly to the EPSPS enzyme. Thus, once the herbicide reaches the target site, the enzyme essentially is nonfunctional; 3) Plants are inefficient at metabolizing glyphosate, thus the molecule remains intact within the plant until it reaches the target site; and 4) Glyphosate does not cause a rapid disruption of plant tissue. This allows the herbicide to be translocated throughout the plant, providing a more effective kill than herbicides that rapidly disrupt plant tissues.

Glyphosate is a broad spectrum, non-selective systemic herbicide. It is effective in killing all plant types including grasses, perennials and woody plants. As a herbicide glyphosate works by being absorbed into the plant mainly though its leaves but also through soft stalk tissue. It is then transported throughout the plant where it acts on various enzyme systems inhibiting amino acid metabolism in what is known as the shikimic acid pathway. This pathway exists in higher plants and microorganisms but not in animals. Plants treated with glyphosate slowly die over a period of days or weeks, and because the chemical is transported throughout the plant, no part survives.

Glyphosate is an organic solid of odorless white crystals. It is a non-selective herbicide used on many food and non-food crops as well as non-crop areas such as roadsides. When applied at lower rates, it serves as a plant growth regulator. The most common uses include control of broadleaf weeds and grasses in: hay/pasture, soybeans, field corn; ornamentals, lawns, turf, forest plantings, greenhouses, rights-of-way. Glyphosate was first reported as a herbicide in 1971. Three related products are now manufactured under the name glyphosate: glyphosate-isopropylammonium and glyphosate-sesquisodium patented by Monsanto, and glyphosate-trimesium patented by ICI (now Zeneca). In pure chemical terms glyphosate is an organophosphate in that it contains carbon and phosphorous. However, it does not affect the nervous system in the same way as organophosphate insecticides, and is not a cholinesterase inhibitor.

Glyphosate can be an effective tool in weed control programmes and is relatively less harmful than many of the products which compete with it in the market place. There is nevertheless evidence of toxic effects on humans as well as environmental toxicity, indirect environmental damage and resistance in some target weed species.

Synonyms: N-(Phosphonomethyl)glycine; mon 0573; Bronco; Landmaster; Ranger; Pondmaster; Rattler 4AS; Roundup 2.5; (carboxymethylamino)methylphosphonic acid; glialka; mon 2139; mon 6000; phosphonomethylaminoacetic acid; N-phosphomethylglycine; Sonic; spasor; Sting; tumbleweed; n-Phosphoromethylglycine; Glyphosate

Chemical name:N-(phosphonomethyl) glycine
Chemical Formula: C3H8NO5P
Molecular weight: 169.08
CAS NO.: 1071-83-6