Created by Dr John Franz glyphosate was formed by combining two phosphonic acids together to produce the molecule that is glyphosate.
Glyphosate is unquestionably the most successful world wide herbicide ever developed with around 2-3bn litres applied every year.
At the time of first marketing wheat traded at £50/t and the leading autumn-sown variety was Maris Huntsman yielding just 5t/ha. The target market being Common Couch. We forget just how common and serious couch was with populations of 80 shoots/m2 causing yield losses of 25%.
The patent for glyphosate ran out in 1994 and by 2014 there were 54 different approval holders. Today there are over 250 brand names to choose from with a wide range in cost per lt.
So what makes one brand more expensive than another?
Firstly the concentration of active ingredient. The range is something like 120 g to 720g active per lt or kg.
The second most noteworthy is the adjuvant either in the formulation or added to it.
Some adjuvants act like washing-up liquid and reduce the surface tension. Others which create emulsions or suspensions leads to a spray with larger droplets; less prone to drift.
Conversely you should also be aware that adding the wrong type of adjuvant can significantly reduce the efficacy of the application. (Is it really “resistance” we are hearing about or is it just an “incorrect” recommendation or application issue?)