In 1971, Glyphosate (N-(phosphonomethyl)glycine) and its salts were first recognised as herbicides. Due to the limited solubility of the acid in water, it was found that the more soluble salts of glyphosate were more suitable for herbicidal purposes.
Glyphosate exhibits many unique biological properties.It is a broad-spectrum, non-selective, post-emergence herbicide with high unit activity on essentially all annual and perennial plants.In contrast to its high unit activity, when applied post-emergence, glyphosate shows no pre-emergence or residual soiul activity. This is because glyphosate is adsorbed very strongly on to the soil particles (either via hydrogen bonding or ionic interaction ar possibly a combination of the two) and is readily metabolized by soil microorganisms. The glyphosate salts are particularly effective against hard to kill perennial weeds, whose regions of growth lie hidden below the soil, and are therefore often difficult to control with post-emergence applications. This is due to the rapid translocation of glyphosate from the treated foliage, of plants, to the roots, rhizomes and apical meristems (ie.regions of growth). This rapid translocation is one of the main things that characterises the action of glyphosate.
Glyphosate exhibits low toxicity to mammals, birds, fish, insects and mosy bacteria. In soil, glyphosate is readily broken down by microbes to form ammonia, inorganic phosphate, and carbon dioxide. The fact that glyphosate has an environmentally friendly action has led to it having a very large impact on worldwide agronomic practices; and has led to it being used under a large variety of conditions in forestry, vineyard, orchard, and residential applications.
The commercial success of glyphosate, as a herbicide, has led to a massive worldwide research effort to find novel methods for its synthesis and a search for proprietary derivatives that might be suitable as competitive products. Several hundred patents have been published in this area since 1970, many with novel process chemistry claims. To date no other derivative or analogue product has been identified or commercialized with a significant advantage over the glyphosate products currently in the marketplace.
