30 Years Of Progress - Formula For Improvement

June, 2004 - Alongside plant breeding, the advances made in herbicide chemistry over the past three decades have been a crucial factor in increasing crop performance, reducing labour requirements and improving arable productivity.

Though often overlooked, at least as important to the increasing overall value of UK weed control have been the equally rapid strides made in herbicide formulation technology in this time.

What is more, Monsanto technical adviser, Manda Sansom argues that these developments have become progressively more significant as value-for-money, convenience, reliability, flexibility and safety have assumed ever-greater importance in commercial practice.

"In the early days, the only real purpose of herbicide formulation was to get the active into a form in which it could be applied," she explained. "But, as the science has developed, the industry has come to appreciate the extent to which the formulation holds the key to the biological performance of the herbicide, the reliability with which it does its job, and its overall cost-effectiveness; not to mention its handling and spraying convenience and flexibility, and crop, operator and environmental safety.

"Compared to the old-fashioned 360 glyphosate with ETA (ethoxylated tallow amine) mixtures of the ‘Seventies, for instance, today’s Roundup formulations deliver more than twice the weed-killing power to the roots. They are rainfast in as little as one hour compared to at least 24 hours; have up to 60% less weight of product per kg of active; can be used in cereal and OSR harvest management as well as stubbles, stale seedbeds and set aside; and allow cultivation in just six hours as against five days.

"They are also less affected by hard water and effective over a wide range of weather conditions and applications, as well as presenting few, if any, operator or environmental risks and broad tank-mixing compatibilities."

There are two essentials in any formulation. First, to get the active into a chemical form that can be mixed with water for spraying – as a solution, suspension or emulsion. And second, to maximise its retention on and penetration of the leaf surface and its speed and efficiency of uptake and movement throughout the plant using adjuvants.

Advances in both the chemical form of the active and the efficiency of the adjuvant over the years have led to major increases in the concentration of herbicides; in turn, allowing dose rates and wastage to be reduced and work rates and spraying efficiency to be increased.

"Old glyphosate formulations used the isopropylamine (IPA) salt with ETA adjuvants," explained Manda Sansom. "This combination effectively limited the concentration of glyphosate to just 360g/litre. We have since developed sodium, ammonium and most recently potassium salt formulations and pioneered advanced low dose, high activity synthetic adjuvants to produce 480g/litre, 540g/litre and 680g/kg Roundups.

"As well as giving more space for the active, modern purpose-built adjuvants have been instrumental in improving the speed with which glyphosate enters the leaf; reducing the localised damage it causes in doing so and thus the amount of chemical absorbed; and enhancing the speed and extent to which it is transported throughout the weed for the maximum long-term kill.

"The fact our Biactivator™ surfactant blend and Transorb™ and Maxin™ technologies have been co-formulated with the glyphosate salt has further reduced the need for adjuvant mixing before application and with it operational risks, time and hassle," she added. "They have also overcome the tank-mixing antagonism of the early ETA formulations, and the need to increase rates or include water conditioners in hard water areas."

Improved operator and environmental safety is another important benefit provided by modern herbicide formulation technology. To such an extent, indeed, that some formulations now carry no hazard classification whatsoever on the label, giving them the best possible COSHH and environmental safety profiles.

"Taken together, the progressive herbicide formulation improvements we have made over the thirty years of Roundup’s life have all added-up to one thing," Manda Sansom stressed. "Huge improvements in overall product efficiency.

"Growers in 2004 can do a far better job with very much less product. They can use it far more flexibility across a very much wider range of applications – from pre-planting treatment to set aside spraying, pre-emergence treatment to harvest management, and spot treatment to over-wintered stubble cleaning. And they can use it far more safely and easily with very much less product and packaging waste.

"There is no doubt too that formulation improvements have played a major part in the Roundup remaining the world’s most popular herbicide for so long. And, despite this, in ensuring European weed species continue to show no evidence of resistance.

"Perhaps the biggest impact of all, however, has been in the increasing cost-effectiveness of the product over the years. In 1974, a tonne of wheat at £58 would buy you just over five litres of basic Roundup. Today’s tonne of wheat at £87 buys you over 25 litres of one of our most modern formulations – with all its efficiency, usability and safety advantages. That’s what I call valuable progress."