With so much more driving a product’s efficacy than its active ingredients alone, CPM investigates the role of formulation and some of the innovative technologies being used to enhance in-field performance.
“We create our own exclusive adjuvants which aren’t commercially available to competitors.” DR MARKUS FIESS
By Janine Adamson
A plant protection product can feature the most innovative and powerful active ingredients on the market, yet that’s irrelevant if the chemistry can’t be successfully delivered to where it needs to be.
Although many variables are at play in ensuring a product lands and stays on target – from application techniques to environmental conditions – one factor that should remain reliable is formulation.
Once registered, a product’s formulation ‘recipe’ is published as part of its safety data sheet, thus vulnerable to attempts of replication, however, the exact intricacies of how it’s made are not. This means there can be much variance in the quality of what appears to be the same chemistry, with the differences becoming acutely apparent both once out of the can, and in the field, explains BASF’s lab leader for delivery optimisation, Dr Markus Fiess.
He adds that despite manufacturers of generic ‘copycat’ chemistry claiming they have an active ingredient and the ability to replicate a formulation, this isn’t completely true. “Only certain materials are fully disclosed on the safety data sheet, other aspects aren’t as detailed,” states Markus.
“You could try to analyse the formulation in a laboratory, but even that isn’t simple because constituents such as adjuvants are often complex mixtures of several components – it’s not easy to clearly identify what’s in there and then copy it.”
INVESTING IN PERFORMANCE
In the case of BASF products specifically, he points out that because the firm invests heavily in R&D, this is a key differentiator compared with others in the marketplace. “For example, we create our own exclusive adjuvants which aren’t commercially available to competitors.
“These are developed and then tested over many years to ensure superior and consistent performance, and are an integral benefit of our formulations. As these belong to us and are built into our products, they simply can’t be copied by another company.”
Explaining further, Markus raises that adjuvants are the cornerstone of a formulation’s performance, responsible for optimum delivery to a target, whether that’s a fungal pathogen or weed. “There’s a sequence of steps during the application process that begins as soon as the product leaves the spray tank, and each is addressed by an individual adjuvant.
“This starts with transportation through the nozzle and how the droplet is formed, followed by spray drift which is dominated by droplet size distribution – all influenced by adjuvants.
“Once droplets reach the plant surface, spray retention comes into play, followed by how those droplets then behave once on the plant surface. Depending on the aim – whether we want the product to be confined in one area or cover the plant surface completely – it influences which specific adjuvant is used in the formulation.
“Then of course we have factors such as improving rainfastness or UV stability, which can be especially challenging with certain active ingredients. Collectively, all of these individual factors are reflected in the efficacy of the final product.”
A solution recently launched by BASF is RevyPro (Revysol (mefentrifluconazole)+ prothioconazole). Trials indicate that RevyProgives exceptional leaf and ear coverage, as well as rapid uptake, with both the Revysol and prothioconazole components getting into the plant faster than other azole products.
BASF’s European technical product manager, Dieter Strobel, explains that achieving this result for growers hasn’t been easy. “Because farmers spray crops when they’re already infected with disease, compounds must work within the plant in order to reach the fungi. This means successful uptake of that chemistry is critical.
“However, when developing Revysol, we discovered it was in fact insoluble. Therefore, we had to find a way to get that insoluble compound inside the plant through a water-based application. It was close to impossible, but with advancements in technology we were able to find a solution.”
Digital formulation expert for BASF, Dr Stephan Köhler, adds that the subsequent challenge his team faced was achieving a high ‘artificial solubility’ of Revysol, particularly when diluted in a tank mix. “In formulation, you can always experiment with solvents to achieve solubility, but how do you achieve this when it’s then in water? Furthermore, for an active ingredient like Revysol that’s hardly soluble, there’s no off-the-shelf solution.
“As such, we had to identify a tailor-made emulsifier to help stabilise Revysol when in the aqueous (water) phase, using computer simulations to look at how these molecules interact. This enabled us to quickly identify which chemical ‘building block’ structures have a good interaction with Revysol and water, as well as which have the most promise in solubilising and preventing the crystallisation of the active ingredient in the spray tank.”
STREAMLINED PROCESS
Without the assistance of computer simulation, there could have been tens of thousands of potential emulsifiers to test in the laboratory, he stresses. Instead, the list could be narrowed down to just a few hundred, which were then built and modelled, again using computer programming.
“Simulating different formulations indicates what the performance of that particular solution may actually be, but this is only something we can do because we’ve invested in the technology and systems to support it.
“Solving the solubility of Revysol was certainly the biggest breakthrough for the Agricultural Solutions division of BASF at that point. We’d been using the technology in other areas of the business, but this was one of the first applications and certainly one of our most significant,” suggests Stephan.
According to Dieter, Stephan’s team would have historically required a lot more time to screen potential solutions, but this computer-driven innovation helped significantly accelerate the formulation development. “Given the likely ban of epoxiconazole, timing was everything and fortunately, we had the technology to speed that process up. Now, these AI-powered computers are everywhere, but at the time it was game changing,” he says.
This team believes this work is what’s improving the uptake of the prothioconazole component of RevyPro. “We were very happy to master the challenge of Revysol’s solubility, but an added advantage came during the development of RevyPro – we were achieving a similar improved uptake effect with the prothioconazole too,” comments Dieter.
“Quicker uptake of prothioconazole means quicker ‘activation’ inside the plant, leading to enhanced activity. This is important, because prothioconazole requires activation to lose its additional sulphur atom, to enable it to fit perfectly in the binding pocket.
“It seems the quicker uptake of Revysol pushes and amplifies the activation process of prothioconazole – something we didn’t expect or intend. Also, once prothioconazole is successfully inside the plant the sun can’t harm it, meaning better UV protection and also rainfastness.
“We’ve achieved many good things for prothioconazole during this process which is why we’re so proud of RevyPro and why it works better than generic equivalents.”
He adds that this is demonstrated when Revysol is tank mixed with generic prothioconazole. “Despite the same quantity of active ingredients, the tank mix isn’t enough to achieve the unique RevyPro formulation effect.
“This is especially important in barley with its disease spectrum. For ramularia, Revysol is a power horse, but for rhynchosporium or net blotch, it’s both Revysol and prothioconazole. In RevyPro, the two actives come together, complementing each other and offering more than the sum of their parts.”
On-farm trials are translating this into yield too, as shown by work conducted by ADAS last year. Hosted by sprayer operator Stuart Butler, the trial compared applying RevyPro with competitor chemistry at T1 in winter barley.
According to Stuart, although low disease pressure last season meant visible differences were negligible, the combine data told a different story. “Anecdotally, there was little to see in the crop, but once it went through the combine we were achieving 0.3-0.5t/ha uplift across the RevyPro-treated plots. Equally as a product, it was easy to mix and poured nicely – it did really well.”
With the trial data now analysed, it’s estimated that RevyPro increased yield by 0.33t/ha, compared with the competitor treatment.
CONTINUOUS IMPROVEMENT
While investment in R&D is mostly used to launch new products such as RevyPro, it can also be applied to improve older solutions too, highlights Markus.
Considering fungicide F500 (pyraclostrobin) specifically, despite being an older molecule, he says it remains effective due to BASF’s continuous improvement of its formulation. “We aren’t selling what was developed 10-15 years ago, we’re many iterations down the line. Importantly, as these have been minor changes, there isn’t a requirement to re-register the product either.”
Two main aspects have been improved with F500 during the years – spray retention and the uptake of the active ingredient into the plant, both driven by improving the adjuvants in the formulation. “We’ve been able to upgrade how the chemistry sticks and is absorbed into the plant surface, as well as its diffusion through the cuticle and waxy layer. This has resulted in improved efficacy,” explains Markus.
He believes that investing in established chemistry such as F500 is a worthwhile exercise, particularly given more plant protection products are being lost than gained. “This drives the importance of maintaining the efficacy of older products – if it still works, there’s no need to lose it. They also all play a valuable role in resistance management.”
And despite older chemistry being easier to replicate by competitor manufacturers, Dieter is less concerned. “Yes, prothioconazole is easy to copy, but we’ve found a point of difference through its combination with Revysol to form RevyPro. This one will be especially difficult to copy without the team’s secrets, we also have IP protection.
“As solutions become more complex in chemical terms, it gives us an opportunity to specialise and create products that are superior for the grower,” he concludes.
This article was taken from the latest issue of CPM. Read the article in full here.
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