The Roundup Brand was born in 1974. Since then products based on glyphosate have become the most widely used herbicides in the world. The benign nature of the molecule to operators and the environment combined with excellence in weed control make it first choice for non-selective weed control.
Once applied to the leaf uptake occurs within 1-6 hours and glyphosate moves through the phloem both downwards and upwards within 5 days. It tends to accumulate in the growing points, then evens up throughout the plant, leading to a gradual loss of green colour followed by death between one and four weeks later.
Glyphosate works at a single specific site in the Shikimic acid pathway to inhibit the production of the amino-acids phenylalanine, tryptophan and tyrosine. Amino- acids are the building blocks of protein molecules and once the biochemical pathway is blocked the synthesis of proteins is interrupted and the plant effectively starves to death. The process is temperature related and explains why treated plants take some time to die.
For more detailed information about the glyphosate mode of action see the glyphosate infomation portal http://www.glyphosate.eu/glyphosate-basics/how-glyphosate-works
This metabolic pathway is present only in green plants. Higher forms of life like mammals, birds, fish and insects are dependent on plant sources to obtain these three amino-acids in their food and neither absorb nor metabolise glyphosate. This is the reason Roundup has such environmentally friendly characteristics.
No other class of commercial herbicide is known to target this site (HRAC group G).
All glyphosate products are not same. While they all contain the active ingredient, glyphosate, the formulation type in which the glyphosate is carried plays a major role in performance.
Monsanto formulation chemists have worked continually since the launch of Roundup to bring out new formualtions with improved weed control, leass restrictive conditions of use and better safety profiles under COSHH
Modern formulations of Roundup are highly active and provide the highest levels of uptake and translocation leading to improved speed, rain fastness and efficacy.