After more than three decades of commercial use some people might think there’s little left to learn about their most widely used agrochemical. But the biggest-ever study of glyphosate practice conducted this year to mark Roundup’s 35th anniversary shows quite the opposite.
The study involved more than 1100 growers in over 60 counties of England, Wales and Scotland responsible for over 350,000 ha of cropping and with in excess of 25,000 years of glyphosate experience between them.
The majority have increased their use of glyphosate significantly over the past 10 years, with six in every 10 buying more than half their annual supply as branded Roundup and the vast majority using the herbicide in at least three of seven different applications.
Even though over 70% of the growers have been using the agrochemical for 20 years or more, their responses highlight a whole host of ways in which most users could improve their glyphosate efficacy and value.
These include employing the active for a wider range of tasks; matching dose rates more carefully to formulation and weed species; taking water quality more fully into account in product choice and use; using additional adjuvants where they are needed; and, selecting products that combine more consistent action under a wider range of conditions with greater flexibility of use.
“When you consider just how much glyphosate products have changed since we first introduced Roundup in 1974 it really isn’t surprising that many growers have a lot to learn about making the most of them,” reasons study co-ordinator, Susan Mintern of Monsanto.
“With Roundup, indeed, the active ingredient is about the only thing that has remained constant as our scientists have pioneered new formulation technologies to meet the changing needs of modern, high intensity crop production.
“At the same time, the number of different branded and other generic glyphosates on the market has exploded in recent years,” Susan Mintern adds. “Not only do they come in a range of different salts and active ingredient loadings, they vary widely in their formulations, surfactant types and loadings, and quality – all of which have a direct bearing on their efficacy as well as approvals and usage.”
With glyphosates being so different these days and capable of being used for so many different jobs, making the most effective use of them is far less simple than it used to be.
It’s vital to appreciate, for instance, that perennial and annual grass and broad-leaved weeds need different application rates and spray timing. Yet the Monsanto study shows nearly 70% of users don’t always identify weeds carefully before spraying (Figure).
Equally, water quality and adjuvant use are widely regarded as important considerations with many glyphosates. Yet only 15% of growers always take water quality into account in choosing and using them, and just 20% always use additional adjuvants with the generics that really need them.
What’s more, even though the majority employ Roundup brands approved for a wide range of label and specific off-label (SOLA) uses and value them for this label flexibility and their consistency of action, only a minority actually use them for all applications.
“Having just one glyphosate in your ag-chem store to use across all applications and under all conditions offers a huge opportunity to simplify management,” points out Susan Mintern . “It means you only need to be familiar with a single label, substantially reducing the potential for error and increasing the likelihood of accurate product use. Your product selection, ordering and storage becomes so much easier too.”
Figure: Main Glyphosate Usage Practices
Overall, the Monsanto study makes it clear that to make the most from glyphosate UK growers must understand three things. First that today’s products are very different from those of the past. Second that all glyphosates are very far from being the same. And finally that care and attention are essential in using even the most reliable and highest quality formulations.